I think you're underestimating the duration of european houses. I've lived in a 200+years old unremarkable stone house in town for a while. If in use, hence with in particular the roof not leaking, they can stay up a very long time. And even abandoned the wall stay for a while. There's a lot of ruins of that kind in certains parts of france.

American-style wooden houses are probably way less durable though, and some spit-and-cardboard modern stuff... urgh.

Wood frame housing lasts longer when it is maintained, not many years ago I rented a century old farm house. It had.. character, but didn't seem likely to collapse just yet. Once the roof goes, the end is near.

Yes; I live in a 200 year old tenement made of stone and it, too, is durable. (A home hereabouts is only really "old" if it's over 400 years.)

However, once you factor in orders of magnitude everything is impermanent. Few 2000 year old dwellings are still in use, and I'm reasonably confident that no 20,000 year old dwellings are still in use.

Another problem is to know where to look. The Old Empires are well known from the Bible or from huge artifacts.

But there were cities with thousands of citizens at what is now Ukraine and Romania, but no one knew about them until the 1980s.

New civilizations unearthed in South America quite often, now to the point that the accepted time of the First Immigration has to be pushed back.

There could be well preserved villages under the sea, thanks to the melting of the icecaps.

We're like John Snow, we know nothing.

I think you're underestimating the duration of european houses.

Depends on the house, obviously. I live in a 60-year old concrete building, which seems to be doing fine, but window frames are wood and not particularily well cared for, so we're replacing them now.

I'd also think that modern buildings have a lot more than just the frame, and a lot of that is made with stuff that needs to be replaced every once in a while - see for example plumbing.

In Finland there are also houses built in the 70's and 80's which have been torn down because they were so shoddy it was easier and cheaper to do that and build new houses.

So, a 200 year old house is kind of an outlier, it's that old because it was good already when built and has been taken care of.

I think we actually tend to OVERestimate the duration of houses, because we only see the old lines that have been cared for and thus survived. A perfect example of survivorship bias. Take a walk in the woods in most parts of Europe and you have a chance to stumble across the ruins of a castle which are barely recognisable as such. I‘ve seen castles that were still in use 500 years ago and today only the lowest layer of the walls still stand.

What will survive from our civilisation is the junk we leave (the stuff on the moon may last longest of all), and maybe some of the large-scale landscaping. If our civilisation had ended in 1900, I don‘t think anything would still left after a few 10k years.

You've just reminded me of Julian May's Saga of the Pliocene Exile, which I absolutely devoured as a teen, placing a bimorphic alien race (and the source of some Celtic mythology) in our prehistory, around 6 Mya — the time of the Zanclean flood filling the Mediterranean.

In her story, the only real vestige of the Tanu and Firvulag's time on Earth (apart from Celtic mythology and possible interference with Australopithicus and Homo evolution) is that their spaceship crash-landing formed the Nördlinger Ries

Some materials are extraordinarily durable and recognizable. If ancient dinosaurs had an industrial civilization, they almost certainly would have had glass, and that stuff doesn't break down chemically, only mechanically.

I also dispute that our civil engineering projects would be hard to detect after a few millennia. But I guess it depends what you mean by "hard". To an untrained eye, sure. To an archaeologist? No, they'd notice it. These are the same people who can find the hole where wood was, and discover deposits of phytoliths, and can tell ceramic from stone when it otherwise looks like a pebble. A big pile of rust-stained conglomerate rock would be pretty obvious to the right eye.

I don't remember the exact precise source, but when I researched for my curiosity this same topic some times ago, a biologist pointed out that we should be able to detect any major civilization very far in the past by seeing traces of weird invasive species patterns.

They should also have been quite more ecologically less impactful than our civilization: there were major extinctions in the past but they have been on a much longer scale than the current one.

I'm not a biologist/paleontologist/etc myself, so I don't know if it was a realistic argument, but it makes sense.

Also, other artefacts of past civilizations even not very technological that should last for a very very long time are things like cut gemstones and worked stone.

On the topic, I remember a short story by Poul Anderson, "In memoriam" (from "All one universe" anthology) that tracked the story of the world from the last days of the last human on Earth to the Earth being swallowed by an expanding sun by tracking the progressive disappearance of the last tracks of humans having ever been there. Likely some of the science is now outdated, but still quite powerful.

The range of possibilities available in timescales where tectonic subduction is an active part of the scenario makes this really, really broad I suppose. But what about looking at it the other way around: what would "we" discover first? Some random surviving cache of artefacts, or equally randomly preserved skeletal remains, or both? An artificial satellite, or space capsule on an aperiodic orbit, or in a Lagrange point, with dinosaur remains in it? Or a similar vessel stranded, aground but not imploded in the Marianas Trench? Or a mine or road tunnel or transalpine excavation exposes a tunnel/bunker/buried city? Or plate tectonics does?

In academic circles this is known as the Silurian Hypothesis, after a 1970 Doctor Who story.

The Broken Earth trilogy touched on this tangentially, but I keep coming back to how we typically identify wooden structures: from the earthworks that go with them. At least for land-based civilizations, you have a chance to discover regular patterns of post-holes for instance. Whether you're looking in the right spot is always the hard part, and one post-hole in a given dig-site doesn't make a civilization.

For modern structures, fast forward time where my house is by 2k years and the most likely way to ID this as a homesite would be what's left of the concrete foundation. Which would be buried in fill and possibly broken as part of a landslide some time in the intervening millennia. The structure itself would be incomprehensible unless the plastic plumbing somehow also survived (the copper pipes would eventually leech into the soil and disappear.)

Punt the timescale out to 50K years and things get a lot dicier. Again, the concrete foundation is the best bet to ID this as a homesite as it's already embedded in the ground and is durable (but not structurally sound) over a scale of at least centuries. On that kind of timescale, this foundation would have been a victim of a landslide and probably subjected to regular flooding (on the scale of decades) to further scatter remains. It would show as an anomalous rock strata.

Put it further to 500K years and we're on the far side of a bunch of climate change. This foundation would be a rubble streak, at best, and possibly embedded in other concrete-rubble from other homesites. The site itself would be long gone.

As always, the best sites for preservation over that kind of time are sites not on slopes, are geologically stable, and aren't subject to water erosion. Even then, it would be the remains of concrete, anomalous rock strata, that would tell future diggers what might have been here. My area has had human habitation for at least the last 10k years, possibly longer, and we know about them mostly from rock-shelters, earthworks, and worked artifacts; hardscapes. If a given culture isn't making hard things? We might never find out about them.

In the deep future there are going to be a lot of rectilinear formations dug into bedrock that will be there over tens of millions of years, and artificial placements of minerals or traces of tar and other materials in long stretches from place to place. Silurians might not have built in right angles but there is a logic to roads where they keep about the same level and they'd be pretty distinctive, same with regular formations of building foundations in circles or ovals or whatever they'd have used.

Michael Scott Rohan's WINTER OF THE WORLD series comes right to mind.

Mass extinctions stay recorded pretty much forever. We have clear records of the Ordovician-Silurian extinction 443 million years ago. We don't really have record from before that because there wasn't really multicellular life to get fossilized.

I'm mentioning that because we're in the middle of the Holocene extinction (caused by us). Long after our cities have been ground to dust the geological record will show a drastic decrease in the diversity of the fossil records.

Together with a massive amount of our fossils, of course. Bones do fossilize well, and there are billions of us.

I’ve often thought that dinosaurs had an industrial civilization. 65 million years is a very long time.

This is something I looked into on my old blog (heteromeles.com) and Hot Earth Dreams, as well as in a crappy Sci-Fi story about what it would take for time travelers to hide their outposts in deep time. It also informed my comments about "Dead God" timescale engineering in the previous thread.

The basic constraint on the existence of paleo-civilizations is the presence of minerals and oil that fuel our civilization. Our ancestors found oil spurting out of the ground in artesian wells. They found tin and copper on the surface close enough to each other to experiment with bronze. They found coal, iron, and gold on the surface, etc. What all this means is that no one prior to them used up these easily available resources.

Now the fossil fuels take 50-360 million years to accumulate. Since the industrial revolution was primarily built on coal laid down 360-300 million years ago or so, that tells us that some prior civilization didn't burn that coal first. We also know that coal and petroleum only survive so deep underground. If it gets too deep, they break down into kerogen. So the coal that powered the industrial revolution likely stayed within a zone where it could be mined, for at least 300 million years (it takes ca. 50 million years to form). Ergo, there wasn't a big coal-burning industrial civilization on our planet in the last 300 million years or so.

We're also missing evidence of massive digging, giant garbage dumps (they're already finding new types of conglomerate rock in modern and ancient landfills, so these would be geologically obvious), and so forth. If you look around, our civilization's footprint is extremely unsubtle, and what we do with things like bulldozers and landfills does leave massive, long-lasting scars that will be visible for millions to hundreds of millions of years. I don't know of any evidence that any paleo-civilization made similarly massive alterations, at least in the last 360 million years.

IIRC, erosion rates vary enormously, but they're on order of a kilometer lost every 50 million years or so. So there may be ore bodies too deep for us to currently mine that erosion will eventually bring to the surface. Conversely, evidence of deep mining for mineral ores will take tens or hundreds of millions of years to erode away to the point where the old tunnel traces are gone and new ores are freely available on the surface again.

Does that mean there was no intelligent life prior to us? Well...remember that my proposed epitaph for our era is "what the fuck were they thinking?" I consider entropy maximization (the ethos of out current consumer culture) to be a sign of greed, not intelligence. Versions of this critique go back to the North American Indians encountering European colonists most of 400 years ago.

Until ca. 200 years ago and more recently, most of the planet was managed by humans better than the mess we're making with our "fuck around and find out" devotion to technological progress and power politics. Humans have left a lot of traces, but generally they're more subtle, mostly because leaving big, obvious traces in the geologic record normally isn't a sign of intelligent land management, but rather a mark of power politics and greed run amok.

So, were there sane paleo-intelligences? Probably not prior to hominids, although there have been smart animals around since the Oligocene (birds, anyway). That said, I'm pretty sure extinct hominids were considerably more technically accomplished than we give them credit for. The thing to remember is that hominids are literally children of the ice ages, so we've evolved in a constantly changing environment. This in turn prioritizes simple, portable, multi-use tools and technologies over big, complicated unitaskers. It also prioritizes things like stone tools, which can be cached near worksites for a century or more, because they don't rust. Being highly mobile also prioritizes memory over writing, and using landscapes as mnemonic devices. These leave subtle traces that can be erased by things like glaciers.

The other thing to note is that Ice Ages are quite rare in the last 400 million years. We're only in the second one since the Permian. The rest of the time, Earth's been in a Hothouse, and the last one only ended in the Pliocene. We're not the only clade to show substantial brain growth during the latest ice age, just the most successful one. It looks to me like Hothouse Earth conditions don't particularly favor big-brained animals, and it's not at all clear to me why this would be the case. It seems to be less obvious than "heat makes you stupid," because humans evolved in the hot tropics during the ice age. Conversely, we shouldn't disregard the possibility that Hothouse Earth conditions selected against human-style intelligence for quite a long time. Hopefully they won't do so in the near future...

If we posit that wooden structures go back to pre-Sapiens times, then what else could be out there but not obvious to us from this remove?

String technology is highly likely. Very useful, doesn't require a lot of other tech to support it, highly impermanent.

String is very useful for tying things together, combining with other string to make ropes which are useful for applying force in ways you can't without them, and enable block-and-tackle, piledrivers, well buckets, and much more.

String is also useful for making fabric. Not just woven fabric, techniques like knitting and nålebinding, not to mention crocheting, produce cloth without needing a loom. Related is felt-making — not really string-tech, but certainly fabric-tech and again very useful: consider the famous Russian felt boots in winter!

And basket-weaving. Soooo useful for storing and transporting things.

as well as in a crappy Sci-Fi story about what it would take for time travelers to hide their outposts in deep time

If you're referring to Ghosts of Deep Time, I rather liked that. Obviously an early novel (like Stephenson's Zodiak), but lots of cool ideas.

It seems to be less obvious than "heat makes you stupid," because humans evolved in the hot tropics during the ice age.

I note that the disease burden on humans rises the closer to the equator you get: it seems that a high energy biosphere (that is, one with more solar flux reaching ground level to drive reactions) also supports faster metabolic processes and more surplus for parasites to siphon off. Especially as many parasitic worms, flukes, and so on seem to need warm conditions in which to thrive outside a host's body.

So maybe it's not so much "heat makes you stupid" as "heat makes you more likely to be sick"?

I’ve just finished 1491: The Americas Before Columbus by Charles C Mann and it leads me to a couple of perspectives.
According to Mann there is a growing consensus that Mesoamerica was densely populated and highly shaped by agriculture; that European diseases resulted in the deaths of 90-97% of that population; the diseases spread ahead of the waves of settlers.
Thus what the settlers experienced as untouched wilderness was actually the overgrown ruins of farms and orchards, abandoned by what was left of the native population; their own numbers being so reduced that the trade networks collapsed and they couldn’t maintain the farms. The scattered tribes were often previously-settled nations forced to adopt a nomadic way of life as a survival measure.
The great flocks of passenger pigeon, herds of bison and so on were not how things had always been - they were populations overcorrecting after the removal of competition/management/predation. The fertile farming soils were not naturally occuring but the result of centuries of agricultural management. Native Americans didn’t live lightly on the land, argues Mann, they actively engineered it through independently-developed technologies unknown to Europeans at the time.
To the settlers, with no frame of reference to how things had looked ~150 years ago, this just looked like how America naturally was.
And here’s where I think this relates to us: say a pre-sapiens species existed and shaped the Earth in detectable ways. Without an outside frame of reference, we have no way of telling whether homo sapiens arrived in a wilderness or an overgrown garden.
Also, Robert Prior @18… another use for string is the quipu for record storage or possbly even writing…

If you're referring to Ghosts of Deep Time, I rather liked that. Obviously an early novel (like Stephenson's Zodiak), but lots of cool ideas.

Thanks Robert. Yes, that's the one. That's where I started to develop my weird taste for deep time thinking.

It'd be hard to hide an industrial civilization in the last, say, 10 million years. High-level nuclear waste, strange deposits in former industrial centers and mines, artifacts in space or on the moon or Antarctica, the oil is mostly gone, a spike in temperature, sudden loss of large animals, a sudden homogenization of species across the world (not just crops, but vermin and weeds), a sudden change in plant and animal species indicating domestication.

I don't know if it's held up, but Charles Mann in 1491 posited that Native Americans had greatly modified the Amazon by spreading useful plants like fruits. James Scott points out that premodern hominids modified the environment extensively with fire. In the geologic record these would appear as sudden, continent-level changes, or layers of charcoal.

So maybe it's not so much "heat makes you stupid" as "heat makes you more likely to be sick"?

My current candidate is more subtle and hard to explain. It's that the nutrient levels in plants correlate with atmospheric CO2 concentrations. Basically, if CO2 is more available, plants put more of it in their leaves and other tissues, primarily as cellulose but also sugars. When more of the plant is carbohydrates, proportionally less of the plant is things like protein, so an herbivore needs to eat more plant material to get the proteins and other non-carbs they need.

Since guts and brains are the two most resource-hungry systems in animal bodies, there's usually a tradeoff. If an animal needs bigger guts to digest less nutritious plant parts, then you'd expect them to have smaller brains. This may be why Hothouse animals had smaller brains. It was about atmospheric CO2 concentrations, not temperature.

Cars are designed to run for ten years but some of the pieces are a lot more durable. Bury a car (or just a car engine) in arid conditions and there will be recognizable gears, axles, and piston heads for thousands of years.

(Or an oxygen-depleted bog? I'm not sure whether those conditions preserve steel.)

Getting much sillier: I've always liked the idea that octopuses are a devolved servitor species from some paleo-Blue-Hades civilization. Octopus DNA is massively hacked compared to other molluscs; they still have RNA-editing features in their biology. The changes are clearly in favor of intelligence and tool use. The fast breeding cycle and gene-tweaking gives you rapid-iteration modification for when you need a new generation of customized servants. And built-in senescence after breeding, to prevent them from getting uppity and overthrowing their masters.

(Maybe they did anyway? Or were just abandoned in place after some paleo-Anthropocene disaster took the civilization down. Paleo-Xenocene? Pick a term.)

I'm mentioning that because we're in the middle of the Holocene extinction (caused by us). Long after our cities have been ground to dust the geological record will show a drastic decrease in the diversity of the fossil records.

Extinction events don't normally leave behind a lot of bones. Usually extinction event evidence is that in one stratigraphic layer there's one set of fossils. There's a bit of a discontinuity, and the layer above it has a completely different set of fossils, typically with no evidence of what happened in the discontinuity. Unless you get lucky and find the right fossil bed.

The big evidence for extinction events is loss of reefs, because these do leave behind massive fossils and do disappear (as we're now starting to see) during major extinction events. We're not talking about photosynthesizing coral reefs as we understand them, because those are shockingly modern (Miocene, IIRC? Definitely Cenozoic). But non-photosynthesizing corals and other organisms have been making reefs and reef-like massive structures for a very long time.

The current concrete schools fuss is a particular type of concrete designed to be cheap and short-term. Only nobody replaced it in time. It's not characteristic of most concretes.

Wooden writing tablets can last longer than you think. The Vindolandia (sp?) finds date back about 1800 years; they were preserved in wet ground. Even the ones that people tried to burn (in Northumberland? Hah!)

The obvious things to look for are road/railway embankments and cuttings. The latter, in particular, will last for geological periods. Ditto surface mining - those big holes in Utah and Western Australia aren't going away any time soon.

If there were a significant number of people (even a few tens of thousands) in an area and building in stone, we'd probably find proof of it unless it was done during an Ice Age glacial epoch in a now-flooded coastal area. Even then, it might be like Dogger Bank where fishermen drag up pieces of stone tools when fishing.

That suggests to me that even if there were, say, groups of hunter-gatherers living relatively sedentary lives in a particularly food-rich area tens of thousands to hundreds of thousands of years ago, it was probably rare enough that the few who did build in stone rather than wood and bone got buried by seawater and river sediment after they abandoned their settlement or died out.

With bigger civilizations, you start getting into stuff like how we can detect the effects of Roman Empire silver mining in the form of lead and other air pollution trapped into Greenland ice core layers.

Most of our civil engineering (bridges, roads, railways, sewers) wears out within a century or so and would be hard to detect after a few millennia.

Just one reason why I had no interest in the Shannara series was that the clip I saw had the Space Needle in Seattle lying on its side, and the show is supposed to be set a few thousand years in the future? Don’t think so.

Also, earlier I saw something on Mastodon about how clay tablets weren’t intended to be permanent, but got fired by accident in fires.

Sunken steel ships are VERY durable. Also, constructions like roads and railways will be easily detectable for huge amount of time.

D’oh! The clay tablet thing was something you re-tooted.

There's a fair bit of Roman concrete still in existence (https://en.wikipedia.org/wiki/Roman_concrete) and the stuff that got thrown up round Europe during the last great unpleasantness shows no signs of falling down.

The stuff that's crumbling now is barely worthy of the name.

That brings up another question ... What if the dinosaurs all died of brain cancer from using cell phones? How did T-Rex get the bluetooth earbuds in?

Smartphones may only be functional for a few years, but their glass and aluminum and now titanium frames should be around for thousands of years.

Robert Prior @ 18:

"If we posit that wooden structures go back to pre-Sapiens times, then what else could be out there but not obvious to us from this remove?"

String technology is highly likely. Very useful, doesn't require a lot of other tech to support it, highly impermanent.

String is very useful for tying things together, combining with other string to make ropes which are useful for applying force in ways you can't without them, and enable block-and-tackle, piledrivers, well buckets, and much more.

String is also useful for making fabric. Not just woven fabric, techniques like knitting and nålebinding, not to mention crocheting, produce cloth without needing a loom. Related is felt-making — not really string-tech, but certainly fabric-tech and again very useful: consider the famous Russian felt boots in winter!

And basket-weaving. Soooo useful for storing and transporting things.

I don't remember where I got the idea from, but I think some pre-literate society used knotted strings as a mnemonic device to encode quite long messages.

How did T-Rex get the bluetooth earbuds in?

Clear evidence for cooperative behaviour! :-)

You may be thinking of quipu, used by the Inca. https://en.wikipedia.org/wiki/Quipu

That Wikipedia article briefly mentions ancient Chinese, Tibetans, and Japanese also using knotted strings to store information.

Lines in the landscape persist in the soil for centuries, and may well persist in the rock strata for eons.

There is a particular line, which provides a distinctive signature for high-speed transport: the cubic spiral.

Not straight lines, nor circles - there are natural processes which can and do leave these lines in the landscape.

But railway lines and high-speed roads do not swerve abruptly from straight lines into circular curves: there is a transition curve, providing a steadily increasing lateral acceleration from zero (the straight line) into the constant centripital force required to progress around a circle (or a chord, a part of a circle forming a bend in high-speed roadway or railway).

There is no natural process that draws these 'railway curves' between plausibly-natural straight lines and circular chords, and algorithmic searches of images can and will detect them, even when they are too faint for humans to pick out.

Note that there is no complete 'spiral' as we would see in (say) a snail shell: transition curves are gentle deviations from the straight-line route, into chords that might only be circular for ten degrees of arc. One more reason why non-engineers can't pick them out in satellite images; but algorithms can.

You need to factor in climate. Even wood survives nicely if the climate is cold an dry. OTOH, mines. An iron age civilization (pre-steam) wouldn't have any mines that were very deep. And the sea level changes. I doubt that we could detect an iron age civilization back when the whales were not committed to the sea. But you need to explain why the only descendants are those that did commit to the sea. I'd expect them to spread widely across the land. Perhaps the explanation of why the civilization collapsed could explain that.

With dinosaurs you don't have that problem. There's been enough continental drift and erosion to hide a full global high-tech civilization. We could eventually discover an outpost on the moon. They could have caused their own collapse through careless orbital re-targeting. (Perhaps they were trying to put in in orbit as a resource to facilitate space-based industrialization.) If something like that happened, we should eventually discover clear signs on the moon, but we haven't explored much of that in any detail. You also need to explain why they didn't have big-game hunters, as there was no tendency for the larger dinosaurs to be dying out. (I'm assuming that any intelligent dinosaur wouldn't be much heavier than a human, but I'm not sure this is a necessary assumption.) (A partial explanation could be some monarch who rigged up the meteor as a doomsday weapon to deter assassins.)

Heretic!

As someone who has made his own netting needles, gauges and nets, I can witness how little beyond making twine is needed. The other, related technology is basket weaving, which needs even less prior work, and is far more useful than just carrying things. In particular, both are good for fishing in lakes and rivers, especially of the form that are common in the African savanna areas, and are used there to this day. Neither last, and nor do fish bones.

Why did I say heretic? Because the theory that such things predated shaped weapons (let alone stone tools) is associated with the Aquatic Ape Theory. Note that this isn't just my view, because I know professional archaeologists who believe these technologies came first, but dare not say so in print. Yes, really :-(

A point some people have missed is that shaping stone is very hard without iron tools, and virtually impossible before (fairly decent) stone tools, so any early buildings would have been no more than the unshaped stone sheep shelters still around in Britain's highlands, probably with a covering of branches.

In a geologically stable area where soil accumulates, the patterns of stone left by neglected stone huts last almost indefinitely. They are gradually randomised by tree roots and (large) burrowing mammals, but that's not a quick process. Of course, finding them becomes tricky proportional to their age, but we can reasonably assume that they were at best extremely rare before about 10Kyr BC.

However, we do now have soil scanners, and a search over plausible areas of early human occupation might find the pattern's of old huts - IF they were there to find! But I can't see anyong providing the generous funding needed to do a proper search for an unsupported speculation.

WRT the clay tablets, I don't think it's reasonable to decide that they were or were not intended to be permanent. Certainly many of them weren't intended to be permanent, being used for school work or such, but this doesn't imply that none of them were fired on purpose.

& cars for 5-15 years: houses for 30-100 years Well, my car was built in 1996 & I've had it, myself for 20 years next Wednesday ... my house was built in 1893 & there are streets of them, around here, built in the period 1870/1 -> 1905. Um.
Civil Engineering Structures ... are MAINTANED, or usually are. See also - local example to you - the { Original & Best } Forth Bridge, yes?
However, some of those Civ Eng structures will last a very long time indeed - I'm thinking of Railway & Motorway & Canal cuttings, embankments & tunnels.

SEE ALSO
Princejvstin @ 14, regarding Winter of the World - highly recommended, if you have not read it.

And ... Clive Feather @ 28
Archaeologist's saying: It's almost impossible to hide a hole in the ground - yes?

Couple of points. An architect got so mad that people were doing sloppy building work in London, that he created a design guide for Georigan-style houses in the 18th Century. Which the dodgy builders promptly used to fake their houses to look more 'modern'. The irony is that because London is situated on clay, which expands and contracts on the order of meters, the houses built to standards generally collapsed because they were too rigid. The cowboy buildings had more flex in them, and they are the ones that have survived the ages (if a bit lopsided on occasion).

So if I was looking for evidence from a long time ago, I'd be looking for people who built on granite or areas that were quickly covered due to a disaster like Pompeii. (Roman concrete can last thousands of years BTW, due to different ingredients).

Secondly, if you're looking more than 10 million years in the past, a lot of evidence might be swept into the crust due to tectonic plate movement. So any evidence would have been destroyed or buried so deep to be impossible to find. Unless of course they were on Greenland. Which is where I would look.

Hence the only other alternative. you would have to hope that your civilization at least got to the Moon where some evidence of their existence might be found (due to the relatively stable surface except for the occasional bombardment). Otherwise it would be practically impossible to prove they existed in the past.

Come to think of it, I'm surprised no one has suggested that the thin layer of 65 million-year-old iridium-rich clay found in dozens of locations across the globe, was evidence of civilization, because a global war that went wrong killed the dinosaurs (which goes back to saying that space might be the place at which there would be evidence of an earlier civilization).

And the fact that layer is so compacted confirms how quickly any evidence would be distorted and buried.

Um, er, that big a crater, that's not a crash landing, that's an impact hole.

Glad someone mentioned Roman concrete. The problem with modern stuff - from concrete to phones, is that they are deliberately, intentionally MEANT to break/fall apart/fail. I can repeat the story of the original Henry Ford, in the twenties, sending men to junkyards to see what in his cars were still in good condition, so he could make them cheaper and more poorly in future cars.

On the other hand, future aliens investigating us... y'know even with weathering, it's really hard to disguise mountaintop removal.

So that's the opening for fiction about complex societies pretty much any time after genus Homo emerged, two million years ago.

Paging Robert E Howard on Gravedust line 2, the Hyborian Age is calling.

If you want to do it Ghosts of Deep Time style ice age Hyboria, with no disturbing artifacts left for our era, I've got a couple of thoughts.

One is to used rammed earth, adobe, etc. as the building material, and set your story in a place with lots of termites who will munch the evidence. Places like, oh, the green Sahara/greater Sahel. Termites aren't as good as glaciers at hiding the evidence, but you can set Hyboria in the Eemian Interglacial if you want some north temperate action on the mammoth steppe.

Two words: ubiquitous megafauna. Use them wisely.

Three words: extreme human diversity. Use it even more wisely.

Oh, and don't forget the old crops, things like millet (China) and kudzu (Sahul). Chinese people keeping the elephants and rhinos out of their millet patches almost certainly happened, ca. 5000 years ago.

Don't get too eager with the sailing rafts and skin boats. You don't want your perps protagonists reaching the New World prematurely.

Finally, the Robert Prior special. If you want to see what a north temperate civilization can look like, check out what the people of the PNW did with stone, wood, and just a bit of copper. They farmed clams and local plants too. Books by Hilary Stewart (recommended!) and Nancy Turner will help with this. Robert, I'm guessing you'll like Stewart's books if you haven't seen them already.

Have fun!

I remember a story I read some time ago in Analog that had space faring Dinosaurs. Basic premise was that the Dino killer asteroid was sent by a fanatic cult colony on Mars. Of course, the survivors replied in kind with interest (thereby explaining why Mars is the way it is today).

Part of the story was in "modern" times, and the question was asked why didn't paleontologists do mass spectrometry on the soil around the fossils to see if anything odd turns up? (like rust deposits). The answer was that they didn't expect to find anything like that and it was an expense.

If we are allowed high tech dinosaurs then we can't forget "The Adventures of Dr. McNinja".

It’s completely obvious that this is prima facie evidence for a lost time-traveller. I mean, come on.

Also “impact crater”? You clearly don’t know how big a GCU is.

I lived for several years in a stone-walled sawmill with a wood frame house and office building built over it. The mill is over 2 centuries old, but the walls are 3 feet thick, it’s likely they’ll survive mostly intact until differential seasonal freeze-thaw cycles break them apart. That could take several more centuries, but there should be easily detectable remnants of the wall for millennia.

Here is a post on a possible elephant civilization in a dried up Mediterranean basin six million years ago.

https://www.deviantart.com/concavenator/art/Gods-of-Salt-773947897

Re: firing of clay tablets. They were definitely fired on purpose when the scribe wanted the tablet to be sturdy and permanent. For instance, a letter sent long distances: if it's not fired, the clay is going to start to crumble from handling in transit. But, oodles of tablets that were kept in archives were not fired. We have some of those tablets today because the archive was almost always in the palace, and palaces were routinely set on fire whenever someone conquered the city.

Source: Brotherhood of Kings, by Amanda Podany, among other books I can't recall the name of any longer.

I'm wondering why no-one has yet mentioned David Brin's "Brightness Reef" ... how well do the colonists on Jijo do for trying to sneak it in by living near the edge of a plate subduction zone?

what we leave behind... might be what other sentient species could also

Sagan deep time disc -- google Voyager; not the lame arse Star Trek but rather NASA;

volcanic ashes -- not just Pompeii, here in North America we had Mt Saint Helens pop off in 1980s, spewed across hundreds of square kilometers; very likely given higher priorities nobody noticed all those smallish items buried under the ashes: coins; nails; street signs; hub caps; soda cans; hamburger wrappers from MacDonald's; foam rubber pillows; Styrofoam coffee cups from 7/11; mock-foodstuffs such as cheese buffs; if the ashes got compressed just right, you'd end up with impressions lasting thousands of years (longer!?);

gold -- iron rusts; ditto most metal alloys including titanium; likely, any sufficiently thick section of high purity gold will endure being trapped inside sedimentary deposits of sand-ashes-gravel and be compressed into rock; how likely there's a sufficiently large amount to be identified? from some circuit-board, given thinness of coating, not likely; a bracelet or petite chain links, not likely; solid one piece such as a human wedding band, maybe? how easily would it be to spot that in a high volume mining operation moving thousands of tonnes daily? would any worker seeing a gold ring announce it to the boss or quietly pocket it?

message in a bottle -- never mind gizmos; you want to leave a legacy "we were here" via something other than a 'Sagan deep time disc' on a spacecraft it would be feasible to encode it into DNA and then patch that into an animal selected for its survivablity; there's lots of 'junk DNA' in many currently living species; could well be multiple "we were here" messages from various civilizations embedded at their peak, perhaps separated by 50 mega-years; problem being species going extinct due to environment shifts and/or radical mutations corrupting that synthetic DNA; so you'd look for a hardy critter, then tweak its genetics to be less prone to radioactive damage as well chemical toxins; small is better; high rate of reproduction is a plus; omnivore willingly eating anything including its own kin being another plus; fast breeding; adaptive; not easily killed; so... cockroaches?

arsenic treated lumber -- while houses come and go, those patio decks could well end up in a muddy patch or outright swamp bog; depending upon regional building codes, manufacture's attention to detail, varying types of anti-rot treatment, there's going to be some chunks of uniformly sized mass produced saw cut timber which after kiln drying will be soaked (possibly pressure treated) in something toxic; arsenic is nasty, cheap and being an element will not decompose chemically but will leach out slooooowly; tainting surrounding soils into a dead zone;

bricks -- billions 'n billions of kiln hardened bricks scattered all over; cheap to make, you only need binder (cliche of straw), clay, water, patience to air dry for a week followed by burning lots of wood to harden into something akin to moderately hard rock; no single brick would be obvious but if there was a collapsed wall buried under gravel and/or sand, it might escape weathering; dozens 'n dozens of near-identically sized rectangular chunks all more-or-less chemically uniform should be noticeable;

fossil bones -- if you graph the populace of dogs-cats-parakeets, all very common pets, there is a remarkable spike upwards inside the twentieth century; in marked contrast there was a deliberately administered die off of horses starting in the 1920s as trucks-cars-buses replaced 'em; most ended up being butchered for sausage (never mind squeamish health codes); and then there's cows-sheep-chicken all of which also went into a steep upspike this century; unless all those animal bones were carefully processed to grind up every bit, you'd find slivers if not always outright intact bones near slaughterhouses; heaps 'n heaps of bone splinters from just three (five?) species ought be noticeable;

I'm wondering why no-one has yet mentioned David Brin's "Brightness Reef" ... how well do the colonists on Jijo do for trying to sneak it in by living near the edge of a plate subduction zone?

Oh yeah, that.

Problem is, abyssal pressures on spaceships will likely crush something and release something, and trenches have a lot of life, even without Deep Ones. So that's just an invisible idiot solution.

Conversely, he had those really cool mulc spiders that were universal solvents with a personality.

They should have just fed the ships to the spiders.

On your fourth point, are you suggesting we read the roaches? On the subject of roaches, with the correct amount of "Narrativium", might they be thought of as engineered species gone feral?

The first thing to go bad in reinforced concrete is rusting rebar, rust occupies a greater volume than steel, cracking the concrete. The solutions might be design and maintenance to isolate rebar from moisture*, or rust-resistant rebar2.

*Deferred maintenance being ever with us, unlikely. 2I've heard stories of contractors using the very least amount, or none at all, of the relatively inexpensive rebar. while there might be a reinforced concrete structure somewhere with stainless steel inside, they'll be rare.

we'd probably find proof of it unless it was done during an Ice Age glacial epoch in a now-flooded coastal area

Given how shit we are at finding that evidence today even when it's less than 20m down, a primarily coastal civilisation as recent as 20kya would likely be undetectable to us now.

On that note, really solid evidence might well come from flying molten rock landing on it. That's how we currently date the early years of the planet, so if you really want to know it might pay to get really good at rapid imaging of the insides of big rocks. Forget the ash piles of Pompeii, look at what's in/under the big lava boulders around ancient megavolcanoes.

A similar type of evidence might come from silicon chips inside bombs and missiles etc. You have weird rocks inside organics inside metal boxes, all designed to deal with vigorous shaking and bad weather. I suspect that even in geological time those are going to leave weird chemical signatures and the nuclear ones will also have distinct radiological ones.

There's quite a lot of non-steel options, glass (fibre) reinforced concrete is popular here. Plus a lot of chopped fibre products rather than long-run fibre. Those are more homogeneous, and weaker but much faster to install. Even over quite long periods there's not much differential thermal or chemical behaviour to make them spallate or otherwise break up, it's going to be bulk weathering that gets rid of them.

So for quite a while there's going to be weird rocks with fiddly bits in. Or just weird layers where "something" took the calcium away and left a drift of gravel mixed with glass/plastic/stainless steel.

Thinking about geologically boring places like Australia, what we see a lot of is people carving grafitti into rocks or painting it under overhangs/in caves. We also get litter left in those caves, right up to "who left this two ton wombat here" level. That stuff doesn't go away on its own, you need to flood the place for a million years or two and dissolve it away then bury it insediment. Or explode it to gravel and ship it off for smelting...

I can repeat the story of the original Henry Ford, in the twenties, sending men to junkyards to see what in his cars were still in good condition, so he could make them cheaper and more poorly in future cars.

The point being that, from an engineering perspective, there's no point in making any one part of the car more durable than the rest of the car. Having a really durable steering wheel that outlives every car doesn't make the car better, so it is better to devote effort to making the worst component better, or alternately lower the quality of the steering wheels so you can undercut the competition.

Ideally it should be like the parson's one horse shay, where every part breaks at the same time…

Chinese people keeping the elephants and rhinos out of their millet patches almost certainly happened, ca. 5000 years ago.

See The Retreat of the Elephants: An Environmental History of China:

This is the first environmental history of China during the three thousand years for which there are written records. It is also a treasure trove of literary, political, aesthetic, scientific, and religious sources, which allow the reader direct access to the views and feelings of the Chinese people toward their environment and their landscape.

Elvin chronicles the spread of the Chinese style of farming that eliminated the habitat of the elephants that populated the country alongside much of its original wildlife; the destruction of most of the forests; the impact of war on the environmental transformation of the landscape; and the re-engineering of the countryside through water-control systems, some of gigantic size. He documents the histories of three contrasting localities within China to show how ecological dynamics defined the lives of the inhabitants. And he shows that China in the eighteenth century, on the eve of the modern era, was probably more environmentally degraded than northwestern Europe around this time.

Indispensable for its new perspective on long-term Chinese history and its explanation of the roots of China’s present-day environmental crisis, this book opens a door into the Chinese past.

https://yalebooks.yale.edu/book/9780300119930/the-retreat-of-the-elephants/

how far back into deep time do you have to go to posit a non-hominid civilization for which little or no evidence has survived to the present day?

Selection effect is a real problem. We know that someone built pyramids in Egypt because any muppet wandering through there can spot them. But the "hills" in parts of the USA that turn out to have been built very recently by people weren't spotted until even more recently. Likewise the stone cities in places like Cambodia - too much jungle, not enough airbourne radar.

So if we postulate a civilisation based on stuff we struggle with now hiding them might be surprisingly easy. How would a tropical megacity work if it was based on wood and pottery, using string instead of clay for writing and canals rather than railroads ? I think it could work, and there might be sod all that would even last 1000 years once there weren't "people" maintaining it.

If we think of octipodes or corvids as the base species it gets even worse. Forget "canals for transport", we're looking at "emus as draught animals" and "anenemones as crops" type stuff. What would corvids want metals for, if they wanted metals, and how would their civilisation work? What would they want that they'd need long-distance communications for? Let's assume they do, and that they get sick of using flocks of corvids to send "smoke signals" over long distances. The obvious step would be actual smoke, so rather than just carrying flaming branches to speed up natural fires (not corvids, but if they can operate a wheely bin operating a stick shouldn't be impossible), so they domesticate fire to use when they want it. Same with plants - they already spread the plants they like and destroy the ones they don't. From there to officially recognised agriculture (per Gammidge) doesn't seem like a big step.

But what would they leave behind? Fire pits, maybe pottery, and some weird species distribution. Plus a lot of strange birds in strange places...

Come on, you're on the continent with the smartest birds. Obviously cockatoos domesticate black kites to carry fire for them, gallahs to forage for them, bell miners to act as security, and lerp psyllids to fill the forests with sugary secretions. It'll be a polyculture.

Tim H. 58:

the question becomes would we recognize a message spliced into DNA if we went looking for it?

if you were going to use DNA as the bottle in context of "message in a bottle" if not cockroaches then perhaps sharks? what other species have changed the least since becoming a success? of course if the critter was optimized by deliberate design then that's how they got so successful...

I will never bow down to cockroaches, however in many ways they are our natural born superiors... heh

them and cheese puffs... my favorite mock-foodstuff... all that will remain behind after our once promising civilization slides into chaos and burns onto ashes... ashes 'n screams...

Heteromeles 65:

what of emu?

heavy freight carrier? or luxury land yacht for those cockatoos too snobbish to fly under their own power and too lazy to walk?

(and then when the emu try to form a labor union in protest to substandard grubs, cockatoos bring in from overseas ostriches as strike breaking scabs)

Cockatoos do seem to employ noisy miners as bodyguards, sort of, when out alone (as opposed to when they are out in groups, which tend to dominate the other birds in the area). At least, I occasionally see a lone cockatoo show up on my deck accompanied by 3-4 miners, who to not hassle the cockie but do attack other birds. Which sort of prompts the question: how do we know it hasn't already happened, is still happening and we just don't know how to recognise it?

... Or we found the first evidence of time travel.

We will clinch it when we find the first 470k year old Dodge buried in a past desert.

It'll be a polyculture.

I see what you did there.

Or, riffing on a familiar idea, perhaps during Hothouse Earth periods practically all larger animals had been turned into the mind controlled pets - or tools - of continent-wide colonies of somewhat-intelligent fungi by the time they reached maturity, and big brains did not matter. In this case, the record of ancient civilizations is hidden in the fossil record, and in some specific species that were, in fact, intelligently molded the same way as cereal crops, farm animals, or household pets were by humans.

Snowball Earth episodes then drove the civilizations extinct and changed the balance of power, and generally lower temperatures meant the well-developed but slow-acting mind control methods lost much their efficacy against plant and/or animal cells. The stars were no longer right...

It might be worth looking at emu for excavations. Bush turkeys build large mounds, and emus already kind of dig. It might be possible to breed one or the other for size and use them to dig canals or other earthworks.

The local sulfur crested cockatoo gang have an arrangement with the indian mynas that seems to amount to "you stay away from us and we won't kill you". On my morning ride the gang regularly descend on whatever food source appeals and the mynas either leave or get chased away. Interestingly the pigeons etc that the mynas hate don't get bothered by the cockys. I do though, that screeching...

The problem with modern stuff - from concrete to phones, is that they are deliberately, intentionally MEANT to break/fall apart/fail.

i mean planned obsolescence is certainly a thing but with concrete i think a lot of it is just cost minimization

in japan i've found (and had to demolish) concrete reinforced with bamboo, i wonder how well that lasts

What would corvids want metals for

s h i n y

meh, wrong attribution, i meant the previous comment from whitroth

Meanwhile ...
Especially for Pigeon! - BBC/YouTube clip of idiot bird/head collision ...

timrowledge @ 51
A "Plate" class GCU, you mean?

Searching for the origin of that factoid I cited earlier, I found this paper that as far as I can say makes a good job of addressing all the major points discussed here, to the point of indicating the more plausible recorded events that may point to an extinct industrial civilization. In particular, I love the ELMOs... Eocene Layers of Mysterious Origin!

https://www.cambridge.org/core/journals/international-journal-of-astrobiology/article/silurian-hypothesis-would-it-be-possible-to-detect-an-industrial-civilization-in-the-geological-record/77818514AA6907750B8F4339F7C70EC6

Of course, from what we can gather here, if an ancient civilization went extinct before reaching the industrial age and/or going global, we would have much less chances of detecting its presence. Also an interesting point raised by the article is that the longevity of a past civilization should be proportional to its ability to be environmentally sustainable, and so by definition less detectable.

James Hogan's Inherit the Stars features an ancient human(-ish) civilization whoae first evidence is discovered on the moon.

Particularly notable for this discussion is the epilogue, which features a junior archeologist bringing his boss a mysterious metal artifact. The reader understands where it came from, but the head archeologist, "knowing" that such an artifact in this strata is impossible, dismisses it as a modern wristwatch that a careless previous set of archaeologists left behind.

AND THIS JUST IN

"...Microplastics have been found in everything from kale, to human breastmilk, to sea creatures at the bottom of the Mariana Trench..."

https://newrepublic.com/article/173780/big-techs-waste-solutions-scam

so... instead of a worldwide iridium layering there'll be microplastics crushed into the fossil record?

How about structures designed to last for multiple millennia, like the 10,000 Year Clock? It's being built by the Long Now foundation (with Bezos's money), specifically to spark conversations about 'deep time'. (It's also part of the inspiration behind Neal Stephenson's book Anathem).

As for Roman concrete, it's a great example of survivorship bias, we can only see the really well made buildings (which were also well maintained). We can't see the many Roman buildings made out of shoddy concrete, by lazy builders, who were only in it for the denarii. Some of which were probably thrown up for equally venial reasons as the UK's current RAAC debacle.

i thought the roman concrete which really lasted was the stuff underwater , as seawater was supposed to react with the volcanic ash component so that it actually became stronger with time

small is better; high rate of reproduction is a plus; omnivore willingly eating anything including its own kin being another plus; fast breeding; adaptive; not easily killed; so... cockroaches?

Minor nit: "only cockroaches will survive nuclear war" is a myth. All insects are far more resistant to ionizing radiation than mammals, but by insect standards cockroaches are wimps. 60-70 Grays kills cockroaches, and as little as 10 Grays makes them infertile. Some ant species can survive 2,000 Grays. (For humans, 50% lethality dose is 4 Grays)

while there might be a reinforced concrete structure somewhere with stainless steel inside, they'll be rare.

Also "stainless" steel is only relatively so. It still rusts, just takes years to do so.

Yes, if you posit a technological society, there are lots of things that last (though small amounts of arsenic treated timber isn't one such), which is why there are ceramics (including glass and hard brick) and stone tools from way back. But the context was early hominids, i.e. a timescale of 300Ky to 3My B.P. The only plausible durable remains I could think of were unshaped stone huts, and those are extremely unlikely, not least because they are generally used only when timber is scarce.

Timber lasts over that timescale only in extremely unusual conditions, and leather, rope and cloth are even less durable. But the evidence of shaped wood indicates that they probably had crude stone tools, visually indistinguishable from broken stones, and may well have several non-durable technologies.

It's definitely a fascinating discovery!

Probably best way to detect a preindustrial civilization would be through fossilized remains of its species. If it had bones, there may be traces of atypical damage (for example bones being worn out by doing a specific job for a long time), remains of clothing and jewelry (even completely corroded metal items leave a chemical trace) or clues pointing to existence of burials (lots of bones in one area, most cadavers in unnatural positions). Fossils may be easy to read if preserved well, but a small localized civilization or a, for example, mollusc one would be much harder to identify as only a small percent of fossil records survive geological upheavals. But some types of rock like limestone karst areas or coal beds (former marshes) can provide a detailed look into past ecology.

For advanced ancient, medieval-like and industrial or postindustrial civilization, geological record may be promising, especially mines. Some mining adits or chambers may become eroded or completely collapsed over millions of years. But some of these also become filled with sediments instead, like caves do. Lots of caves in various karst areas are very old and if the process that led to the emergence of a cave ceases, they fill with sediments and may stay undisturbed in the bedrock for a really long time - many European limestone massifs are, for example, Devonian or Silurian. A mining adit or a complex of mining works, filled with sinter or clay, may become deformed over years, but should be still identifiable as something not natural.

One of the unexpected finds from stone age settlements in Denmark were "kitchen middens" which were essentially huge piles of oyster shells, but a 100% vegetarian culture or one far from the coast would leave nothing like that.

Another thing which seem to last forever is charcoal.

27 para 2 - Vindolanda Treat the link as a source; there are several Wikipedia pages, and lots of other external links, just for this one fort.

30 - Sunken steel ships are VERY durable
Tell that to the RMS Titanic!

35 - And then there's also Ogham. Most of that was deliberately destroyed following the Synod of Whitby though.

43 - Even with selection bias I can be the 3rd to post in this thread and say that I live in a house over 100 years old. IIRC Nojay is in this "club" too.

86 - Can't see why coastal kitchen middens should be rare in Denmark; they're "as common as muck" in Scotland.

String technology is highly likely. Very useful, doesn't require a lot of other tech to support it, highly impermanent.

String is very useful for tying things together... for making fabric... And basket-weaving...

You are 100% right on all of that.

It's also useful for weapons. As an existence proof I offer this video, How To Make a Balearic Sling, in which a person starts with a pile of loose fibers and ends with an effective and efficient distance weapon. His high-tech support for this involves a cutting implement, beeswax, and optional but convenient clothes pins; I can't imagine our neolithic ancestors not being able to do this.

Also, the Primitive Technology guy has shown himself making baskets.

»Can't see why coastal kitchen middens should be rare in Denmark«

Nobody have said they are.

I said they were "unexpected", because in 1848, when the first one was found, everybody would have told you that it would be physically impossible to find something like that, and suddenly the had their spade in one[1].

My, probably too subtle, point was that to think about archaeology in the 100ky domain, you need to think more about the physics of preservation, than about the artifacts of culture.

[1]Similarly, twenty five years ago, the very idea of finding DNA having survived hundreds, much less thousands of years, were "patently impossible, and five years later we knew that at least one person on Greenland long time ago had a genetic tendency to sticky earwax.

...here in North America we had Mt Saint Helens pop off in 1980s, spewed across hundreds of square kilometers...

May 18th, 1980. And I was downwind of it!

The ash fall is detectable over vast distances, and I'd expect geologists to be able to identify it millions of years in the future, but the deep burials were (fortunately) mostly in lightly inhabited land. You're right that the buried human litter can be dated very precisely.

The buried artifacts included my grandmother's car, south of Portland; it only got a relatively minor dusting but she was not happy when she saw what a covering of sharp-edged rock dust did to the paint job.

Yakima got about an inch of ash. When faced with an inch of annoying stuff that had just fallen from the sky, the city used its default strategy for this event and plowed it into big piles at the edges of streets and parking lots. It works a treat for snow; just get it out of the way and wait for it to melt. The volcanic ash did not melt and after a few months it became obvious there needed to be a Plan B...

Volcanic ash melts, when you get it hot enough... ;-)

You can use it to condition the blades of gas turbines.

My, probably too subtle, point was that to think about archaeology in the 100ky domain, you need to think more about the physics of preservation, than about the artifacts of culture.

We don't agree on much, but I completely agree with you on this! Sadly, I don't think it's a subtle point. Instead, I suspect it's a set of out-of-context error problems for most of the people who try to think about deep time using their normal metrics.

This isn't to be elitist, because to me it's a matter of learning and practice, not a special talent. I do suspect that it takes more work than most people to get comfortable thinking about processes on the thousands to millions of year time scales, and more work beyond that to get rid of the "geological time" versus "normal time" crutch that many geologists and evolutionary biologists use. I call it a crutch because I've observed that using too many different time scales ends up confusing users into forgetting that each ruler they use has its own rules. "A few years," "a few centuries," "a few millennia," and "a few million years" all mean really, really different things. People tend to focus on the "few" and forget that it's the least important part of each phrase.

i thought the roman concrete which really lasted was the stuff underwater , as seawater was supposed to react with the volcanic ash component so that it actually became stronger with time

I think Roman concrete gets it's good rep from the Pantheon, which is a non-reinforced concrete building that has been a tourist trap for almost 2,000 years. The thing to realize is that it was built by an emperor who was trained as a civil engineer, who knew concrete and could afford to use the best materials for everything in the building. Couple top-line materials with top-level engineering and give people a reason to keep it around, and it will last.

Otherwise, Phuzz's comment about survivorship bias is mostly correct. The three other factors with Roman concrete are: 1) by accident, they had access to the best materials for making concrete in the world, so other things equal, their work does last longer, b) non-reinforced concrete normally lasts better than reinforced material (our fatal mistake in the 20th century), and the Romans never used iron reinforcements and III) by the time they built the Pantheon, they'd been working with concrete for centuries. We've had our version of concrete for less than 150 years, and we're still learning from our mistakes.

The only plausible durable remains I could think of were unshaped stone huts, and those are extremely unlikely, not least because they are generally used only when timber is scarce.

I just got some more calls on my Gravedust rig. This time, it was from a bunch of people from the Aztecs in the north to the Incans in the south, who wanted to show you the tops of the pyramids they built with stone tools. They're upset that they can't bring you back in time to educate you properly...

Oh, and the modern Egyptians want to dunk on you English again by pointing out that the great pyramids (largely built with stone tools) are older than Stonehenge and most of your little huts.

Now imagine and octopus, a corvid, or a parrot making string...

How do yall plan to domesticate emus when you list a war against them? With machine guns?

Now imagine and octopus, a corvid, or a parrot making string...

I expect an octopus would be really good at it, once the octopus got the idea.

Birds would have more trouble, as it's a task made much easier by having multiple manipulators; they tend to top out at one beak and one grasping foot.

Now I'm wondering what sea plants lend themselves to fiber production and realizing I've got no idea.

Also, has anyone ever tried teaching octopuses to do fun tricks with strings and ropes? That sounds like a thing pretty much any human near octopuses could try but a quick web search was not helpful.

I said they were "unexpected", because in 1848, when the first one was found, everybody would have told you that it would be physically impossible to find something like that, and suddenly the had their spade in one[1].

What made "everybody" think that such kitchen middens were impossible?

That sounds like the set-up of a bad joke. An octopus, a corvid, and a parrot enter a ropewalk...

You are being silly again, and ignoring my first paragraph. Those peoples were modern humans (i.e. NOT the same (sub-)species as 400Ky ago, and they left lots of advanced stone tools (again, unlike 400 Ky ago).

Feel free to advance a theory that any of your examples date from before the evolution of H.s.s.

Re: "message in a bottle"... yep, and then, when that particular bit of "junk" DNA (which we've been learning isn't vaguely "junk" turns out to have been the directions to protect you from disease X....

Good news: at the building supply big box store, Home Depot, they sell plastic-coated rebar.

The longest-lasting tell-tales are probably failed stonework. If all the completed Old-Kingdom monuments were somehow removed from Egypt we'd still still know that the civilisation there made big stone things because of all the broken ones left behind in the quarries. They aren't going to weather away any time soon. They're just revealingly straight-and-regular grooves in the bedrock.

Therefore, to be undetectable in deep time, a culture has to have skipped the monuments. Variously because they never got to even Old-Kingdom levels of tech; or because they didn't civilise enough to have the spare labour; or because they didn't value such things; or because they skipped that stage entirely (which becomes some kind of uplift store and retreats into fiction).

No, the point is that he deliberately was not making something that cost a lot of money last. Rather than selling to new people, he wanted people who already owned one to replace it... exactly like the scum who make "smart" phones.

Replace capitalism, esp. late-stage capitalism, with something that values what we have, and that changes.

Cheese puffs? Don't be silly, it's Twinkies (tm), which are individually wrapped, and what the roaches 10,000 after The Big One will survive on.

Bones, esp. fossilized? Worn out? Let's try something far more modern, like, say, me. I am planning on cremation; otherwise, well, there are these posts in both knees that are clearly artificial (both knees having been partially replaced due to arthritis). There are a lot of people with replacements... and that, of course, shows a) we take care of our wounded, and b( gives an idea of how far along in medicine and chemistry we were.

That, or they didn't like cats, and so never had large grain reserves, or major agriculture.

I mean, cats are why we're here.

H,

According to this research, what makes Roman Concrete so good is that it is "self-healing", because it has minute "clasts" of undissolved lime in the mix. This means that if cracks form, atmospheric moisture can get in and help set these clasts in the cracks.

Enjoy:

https://www.sciencedaily.com/releases/2023/01/230106144441.htm

»They aren't going to weather away any time soon.«

100ky isn't "soon" for limestone, very few chissel marks would be left by then.

»What made "everybody" think that such kitchen middens were impossible?«

All branches of science teach certain dogma, "neutrinos have no mass", "We are never going to find any food from the stone age", "Fish feels no pain" and so on.

The problem with assumptions like that being taught as dogma, is you explicitly tell the students and thus future generations of researchers, to ignore the alternatives.

Because everybody "knew" finding food from the stone age was "impossible" there were a lot of weird theories about how oysters could have just happened to die in a huge pile which must, obviously, have been under water at the time etc.

I mention the mass-less neutrinos, because nuclear reactors emit a LOT of antineutrinos, but since everybody "knew" they were mass-less and therefore didn't interact with matter, any report about living close to nuclear reactors at best mentioned them in a footnote, saying they "went straight through everything without doing any kind damage". Transpires they do in fact not, and that the barely detectable childhood leukemia signal may not have been random noise after all.

Yes. Many shells are very durable, but the problem is that all that oyster middens show is that some animal foraged for oysters and left the shells in a particular place. Why people thought that they were impossible to find (rather than just unlikely) is something I find baffling.

https://link.springer.com/referenceworkentry/10.1007/978-1-4020-4409-0_146

A good solid Silurian Hypothesis novel is needed

Heteromeles 96:

So... an octopus, a rattlesnake, a raccoon, and a cockatoo all walk into a bar... and they celebrating because they collectively rule the world ever since those foolish bald monkeys slaughtered one another over petty differences in skin tone, religion, woke-ism, Trump-as-demon-Trump-as-Jesus, etc

paws4thot 91:

...and everything can be airdropped at least once

Prebral 85:

what every SF author exploits (including Charles Stross) is any anomaly in teeth... dental work... myself as an extreme example... fourteen capped teeth... a pair titanium posts and too many root canals for me willingly to recall to count... if there's teeth in the fossil record then examine each for drilling and filling with silver-steel-gold-lead (thank god only a few unlucky people had cavities filled with lead before dentists realized the harm potential)

now I gotta drink lots 'n lots of tequila to shake off the mortal terror of any human-sized dentist (of whatever species) having to perform a root canal on a T-Rex[2]

ilya187 82:

I don't know how it is elsewhere but here in East Sodom[1] the cockroaches have gained a degree of invulnerability attribute to Marvel's Wolverine; last night as I wrote my diatribe I paused to hunt-kill-dispose of Moby Roach... four inches in length, it reached speeds exceeding 200MPH and I had to hammer it a dozen times with a 14oz can of Heinz Veggie Baked Beans till it squished satisfactorily; yes, yes, I know I should have used either a bigger can or an actual sledgehammer but the Heinz was in immediate reach; as to the radiation issue, my understanding is the fossil record indicates very little variance for this species of insect; never mind the synthetic grays, there's background radiation always triggering mutation in all species, so less about nuke-bombs and more about UV-sunlight-pitchblende-rock; robust DNA resistant to mutation, tweaked by folks seeking a bottle for their message;

=+=+=+=

[1] East Sodom (AKA: New York City) deemed to be the most sinful (sin-filled), decedent locale on the Eastern Coastlines of North America; whereas the title of West Gomorrah is a three-way tie: Los Angeles/Hollywood/Silicon Valley

[2] "Of Ants and Dinosaurs" by Liu Cixin; "Prostho Plus" by Piers Anthony;

A good solid Silurian Hypothesis novel is needed

At the Mountains of Madness? The Silurian Hypothesis is not a new idea. You could also call it The Valusian Hypothesis (from Robert E Howard's Kull Cycle) or the Yithian Hypothesis (another famous HPL work).

If you want a more recent version, check out McLoughlin's Toolmaker Koan. (1988 https://www.amazon.com/Toolmaker-Koan-John-McLoughlin/dp/067169779X/ Check out the early use of feathered dinosaurs).

According to this research, what makes Roman Concrete so good is that it is "self-healing", because it has minute "clasts" of undissolved lime in the mix. This means that if cracks form, atmospheric moisture can get in and help set these clasts in the cracks

Thanks!

There's two levels to this. One is that pozzolans are generally reported to be as good as it gets for cement. This is in comparison to the fly ash and other stuff used in modern Portland cement. This part does matter even today, and the Romans got lucky to have so much of it available so close to their capital.1

The other is that this research suggests they added some quick lime in as well as the normally used slaked lime. That's new and cool information, and probably came about due to the centuries of experience they had from making cement.

As with the carboniferous era the plasticene will end when enough things start eating the plastics which is likely to mean they mostly disappear. Our occasional landfills are not really equivalent to the huge swamps covering every bloody thing.

Which makes me wonder about stuff like aromatic halocarbons but it turns out those are often bioactive so artificial ones are no doubt already targets for hungry microorganisms.

Per chat above, we really want things that are physically robust, inedible, and chemically inert. As well as obviously artificial. Which is why I was leaning towards a nuclear submarine. It's got all the weird shit you could possibly want in a relatively combact package that's somewhat physically robust.

But the flip side, how technological can a species get without leaving obvious signs a few kiloyears later... hmm.

FWIW the local gangs of Psittaciformes seem to treat rope and string much as they treat thin branches... either fun or annoying depending on their mood. Have not seen them using string as a tool, but I don't spend much time watching. "Sailing Wisdom" on youtube have combined two parrots with a sailboat without obvious "who stole my bit of string" problems, albeit they do have a lot of shred-able toys for the birds and have trained them not to attack the rigging. They're definitely not crew, though...

As with the carboniferous era the plasticene will end when enough things start eating the plastics which is likely to mean they mostly disappear. Our occasional landfills are not really equivalent to the huge swamps covering every bloody thing.

It's messier and more interesting than that. The Carboniferous was the last time Earth was in an ice age (!), and the ice age ended in the early Permian with the onset of Hothouse Earth. Subsequent to that, termites and wood-rotting fungi evolved during the Hot House, and they're efficient enough that subsequent coal deposits (e.g. the Paleogene Green River) are a lot smaller.

Plastics come mostly from oil, and when it's gone, their production will mostly stop. There are already growing ecosystems of bacteria and fungi breaking plastics down--slowly--but when the plastic is gone, probably no more will be produced, and the plastic decomposers will evolve into something else.

We're currently in as close to a New Carboniferous as we're likely to get on this planet ever again. Despite climate change, we're in an ice age, and we'll stay in one for millions of years from now. The current ice age due to things like the placement of continents and the existence of the Tibetan Plateau. There will be glaciers again after our carbon is down. In maybe 125,000 years?

If someone wants to write weird SF, posit genetically engineered super bamboo and other trees that resist decomposition. They're created both to sequester carbon and to serve as green building materials in place of steel and concrete. As they spread, they become too successful, dominating forests. Over time, a New Carboniferous takes hold, with soaring O2 levels, growing glaciers, burgeoning tropical swamp forests, temperate bogs swallowing farmland, increased fires, and bigger bugs. Among other things. (note: I'm not developing this idea further, take it if you want it).

paws4thot @ 87:

43 - Even with selection bias I can be the 3rd to post in this thread and say that I live in a house over 100 years old. IIRC Nojay is in this "club" too.

I hope that someday I too will live in a house that's over 100 years old.

I have a more techno-utopian view of that particular niche. I think we're going to see wholesale production of bioplastics from material that would otherwise be wasted feeding people, competing with the increasing number of things that discover they can eat (bio)plastics. So there'll be the usual messy biological arms race between things that eat food before we do (and things that eat people), things that want to turn food into more useful stuff, and things that eat the useful stuff.

Meanwhile crooked timber is looking at the (laentable!) increasing polarisation in politics between the "burn everything to the ground" side and the "climate catastrophe is bad" crowd, with various idiots calling for sensible compromises... not so much a smaller catastrophe as less argument about whether we should avoid the catastrophe at all.

Heteromeles @ 94:

Otherwise, Phuzz's comment about survivorship bias is mostly correct. The three other factors with Roman concrete are: 1) by accident, they had access to the best materials for making concrete in the world, so other things equal, their work does last longer, b) non-reinforced concrete normally lasts better than reinforced material (our fatal mistake in the 20th century), and the Romans never used iron reinforcements and III) by the time they built the Pantheon, they'd been working with concrete for centuries. We've had our version of concrete for less than 150 years, and we're still learning from our mistakes.

The purpose of the reinforcement is to add tensile strength to concrete. Concrete withstands compression, but doesn't stretch very well.

We use steel for rebar because it's fairly inexpensive. But, I think there are other materials that wouldn't be subject to rusting away like steel does that might make better reinforcement.

A step in the right direction, but any break in that coating, the end is only a matter of time. For example, 45 years ago white powder coated steel wheels were popular on light trucks, relatively inexpensive and looked good, until a wheel with a break in the coating was exposed to road salt.

The purpose of the reinforcement is to add tensile strength to concrete. Concrete withstands compression, but doesn't stretch very well.

Others should chime in about this. Basically, I agree with you, but I look at the problem differently. To me, it's about structural lifespans, needs for the structures, and the availability of critical materials.

The material problem, as I understand it, is that cement and concrete require "sharp" sand, meaning mineral sand with angular grains that interlock to make a firm solid. Round sand, like what's in deserts, is useless. The grains don't interlock, and cement or concrete made from it is weak. Long story short, we're running low on sharp sand to the point where "sand mafias" show up in places like India. When we run out, we're forced to pulverize hard rock into sharp sand, which is energy intensive at a time when that's a problem.

We both agree that reinforced concrete structures don't last as long as unreinforced ones do. This is a problem when we build so much of our infrastructure with the stuff and need to replace it. It's not like we know how to recycle the sand in old concrete, so in addition to building new things, we're stuck rebuilding necessary things every few decades, because reinforced concrete doesn't last.

Worse still, concrete's become a symbol of modernity, to the point where concrete skyscrapers get built throughout the tropics, even though they're not very comfortable even with energy hungry AC. And conforming to such symbols of our ideology of conspicuous consumption strangles development of other building materials, like African "mud" based architecture, which can be cheaper and more comfortable when done right.

So reinforced concrete's kind of got us stuck. Our demand's only going to grow, we can't recycle it, and we're running short on raw materials. It's going to make the future even more interesting than we might like.

My comment above in the "New Carboniferous," about gene-hacked tree,s actually is something people are experimenting with. Big, fire-resistant wood buildings could sequester a lot of carbon, and the more so if they last longer than reinforced concrete. Such plants, be they bamboo, rubber, coconut, or (most likely) poplar and pine, would hugely change the global ecosystems if they took off and replaced both concrete and ordinary trees. Something to think about, maybe?

»We use steel for rebar because it's fairly inexpensive. But, I think there are other materials that wouldn't be subject to rusting away like steel does that might make better reinforcement. «

There are a lot fewer than you imagine.

Steel happens to have a coefficient of thermal expansion very similar to that of portland cement based concrete, which allows you to embed the steel in the concrete so the latter provides corrosion protection of the former.

Where durability of the concrete is a priority, for instance in the three great bridges in Denmark, optimizing this aspect of the concrete formulation gets a lot of attention.

(I happen to know they guy who did the formulation for the two largest bridges, and who is currently busy with the concrete for the tunnel to Germany.)

Using tensile strength materials with different coefficient of thermal expansion is possible, but adds a lot of complications and limitations, with lack of adhesion being the most obvious.

On the other hand, having no adhesion between the tensile strength material and the concrete allows you to calibrate the tension precisely ("post-stressed concrete"), which has other benefits and allow for more daring architecture.

Trouble is that wooden building have the same exposure to capitalism that concrete ones do. I haven't seen anyone in that side of the industry talking about designing for the long term, and it'd be a bit foolish to anyway IMO - too much change in the expected life of buildings already, but we have plans to speed that up! Concrete or wood, your "multi century" building isn't going to work too well if the ocean comes and visits it every few months.

Recycled concrete is very much a thing, but the recycled bits are used as aggregate rather than sand. It's kind of annoying.

I can't find the paper now, hut there is at least one report on recycling a "recycleable" building that had lots of hints and tips for people thinking of making recycleable buildings (mostly of the form "watch everyone on site because a can of spray foam can wreck a surprisingly large number of formerly recycleable timbers").

Annoyingly a lot of "sustainable bamboo flooring" uses non-biodegradeable bioplastics to hold it together. My guess right now is that anything waterproof, insect resistant and "do not incinerate" is probably not your friend. I'm struggling to get answers to "it's recycleable, how do I recycle it".

»The material problem, as I understand it, is that cement and concrete require "sharp" sand«

Theoretically speaking, "concrete" is high compression strength particles held in contact with some kind of glue, and portland cement + geology is just one kind of concrete.

The crucial property of concrete is that the particles are brought in physical contact with as large an area as possible, and if you think about the particles as spheres, it will be obvious why having particles spanning a range of sizes makes the best concrete.

The 'round sand' vs. 'sharp sand' follows from that: If you can get hold of sharp edged sand, it will pack tightly and a finer particulate will not be necessary, if you use round sand, you need something else to fill the voids between the corns of sand.

This is also why adding volcanic ash or fly ash to the mix improves things: Even sharp sand can be packed better using micron-sized particles.

Portland cement can fulfill the dual role of binder and finest particulate, but it is an expensive formulation to use and it requires active cooling during hardening or it will crack when the water turns to steam.

The second most popular kind of concrete is epoxy-concrete which is used as machine beds/chassis for high precision CNC machines, because it can be made incredibly strong, with high dampening of mechanical vibration and almost zero coefficient of thermal expansion.

Engineering colleges in USA have an annual "concrete canoe race" contest, which is at the same time technologically impressive and slapstick entertaining. Highly recommended if you have the chance.

»people thinking of making recycleable buildings«

We had a sharp focus on sustainability when we built our house, and because I ran a blog on the danish engineering associations newspaper, I was able to get in touch with a lot of people who knew a lot of things.

No matter which way you turn, the lowest hanging fruit is making the building last.

That is not just a matter of choice of materials and technique, but also of designing the building with as few constraints on its use as possible, so that people a couple of centuries down the road will still find it a nice and fit container for their life.

The second thing is to reject almost any building material or technique developed after approx 1960, because they have all been developed to make buildings cheaper to construct, at the cost of maintainability and durability.

Our rule became "if it is hard to replace, it has to be geology", so for instance our floor is not insulated with EPS plastic but with "Leca nuts" (= fired clay nuggets) and we do not have a "radon membrane" (= plastic sheet) under the poured concrete floor plate, we have a pipe venting the radon above the roof.

One specific thing to avoid is "functional mortar" (= sand/cement concrete) between the bricks, because that makes it impossible to clean them and recycle them.

To the surprise for both us and our contractor, our house ended being cheaper because of these choices, because most of the "smart" modern choices are optimized for just one discipline, often at the cost for other disciplines.

For instance using precast light concrete elements for the interior walls meant that they were airtight, so no fiddling around with plastic membranes and glue, which is required to reduce leakage in a wood-frame+rock-board interior wall to meet code.

It also meant that the conduit for cables and boxes for outlets could be precast into the elements, so the electrician did not have spend time to pull conduit and then spend time taping the leakage around his conduit and the plastic membrane.

The piping for the radon ventilation took just a couple of hours for the concrete crew before they poured, normally they spend an entire day getting the radon membrane glued into place and then they have to be very careful not to damage it while they pour the concrete.

We chose to use a hard sub-roof (plywood + tar paper) under the tiles, rather than the usual "textile membrane roll material". Approx same cost of materials, ten times the durability, 10dB extra noise reduction, and the crew could put their foot down wherever they wanted while mounting the solar panels and laying the tiles.

All in all I am confident that two hundred years from now, the house we built will still make somebody very happy.

(If you want to see how fast a competent crew can raise a house from precast concrete elements: https://www.youtube.com/watch?v=_SwHlkyEoYE)

Sea plants for fibre: I think sea grasses are about it, possibly drifting coconut husks ( Unless your chosen organism can climb out to gather) .Algae tend not to have easily extractible fibres in the same way vascular plants do. You now have me wondering about animal sources-farming mytilid mussels for the byssus fibre? I know it has been done but I have doubts about it as a viable start from scratch technology.

peter w
Unless your chosen organism can climb out to gather
Land-Crabs?
The Pacific Tree Octopus?
Any other suggestions?

Come to think of it, I'm surprised no one has suggested that the thin layer of 65 million-year-old iridium-rich clay found in dozens of locations across the globe, was evidence of civilization

It was quite a prominent plot point in The Toolmaker Koan by John McLoughlin (published in 1987).

Or, riffing on a familiar idea, perhaps during Hothouse Earth periods practically all larger animals had been turned into the mind controlled pets - or tools - of continent-wide colonies of somewhat-intelligent fungi by the time they reached maturity, and big brains did not matter.

I really like this one!

The attributes of a useful tool are: it lets you do something you can't physically accomplish yourself, and it's durable (so can be reused). An ideal tool would also be multifunction and self-replicating. If you're an effectively immortal fungal network that can brain-control vertebrates then you can harness their brains to think for you whenever necessary, selectively breed them for desired traits, and adapt them to meet new requirements.

Why haven't we found their cities? Because they don't build them: they're sessile fungal transport networks buried under the topsoil. Why haven't we found them? Because they don't fossilize (no bones!). Why haven't we found their tools? We have, we have entire museums full of them!

Ever wondered why Azdarchids got so big? Because the god-fungus wanted to colonize islands or continents a long way from home and shipping a quarter of a ton of compost along with its spores was a no-brainer. So the really big pterosaurs were left over after the continental colonization project and went feral-ish, eating seafood and shitting valuable nutrients on land where it's useful to their makers.

And so on ...

so... instead of a worldwide iridium layering there'll be microplastics crushed into the fossil record?

Microplastics are a problem that will solve itself well within geological time.

The "micro" part is the clue -- they're polymer beads with a huge aggregate surface area. Which means they're exposed to a lot of microbial life. We already know of some fungi and bacteria that can break down polyethylene; my guess is that if there are enough microplastics out there, evolution will tend to favour bacteria that can chow down on them.

This process won't happen overnight but over a 1-100MY period the microplastics will mostly vanish from the fossil record except where they've been segregated from the biosphere.

Speaking of genetically modified organisms producing useful materials, spider silk is now being spun by silkworms for the first time, with about six times the strength of kevlar. (Lots and lots of exotic genetic manipulation was required ...)

If this can be scaled up, then I think that rings down the curtain on nylon for most practical purposes. (Would you prefer to wear nylon or spider silk? Never mind the bulletproof vests.)

If we don't exterminate ourselves there are going to be more headlines like this. And more products that replace plastics/metals with biomimetic substances that are better.

Charlie
Have you or anyone else also read the same J McLoughlin's "Helix & the Sword"?
A very different space opera ...

"Spider Silk" - not just that ... the current advances in "Materials Science" - & most importantly, the Materials Technology to manufacture said materials is advancing at a ridiculous rate.
Which reminds me ...
It is looking as if that "Room-Temperature Superconductor" we were discussing earlier this year was a bust, after all?
Which is a pity, but you can bet your boots, that lots of very ingenious people will be working on it, so, probably, sooner rather than later, something of the sort will show up, yes?

Heteromeles @ 123:

We both agree that reinforced concrete structures don't last as long as unreinforced ones do. This is a problem when we build so much of our infrastructure with the stuff and need to replace it. It's not like we know how to recycle the sand in old concrete, so in addition to building new things, we're stuck rebuilding necessary things every few decades, because reinforced concrete doesn't last.

I can agree that concrete should last longer if we can find other materials to reinforce it with that aren't so subject to rust.

»over a 1-100MY period the microplastics will mostly vanish from the fossil record«

PVC is about 30% Chlorine by weight, and so far nobody has shown the least inclined to eat that.

It cannot entirely be ruled out that it would be possible for somebody in salt water to do so, but motivating them to do it will be uphill

PVC is about 30% Chlorine by weight, and so far nobody has shown the least inclined to eat that.

Er, chlorine makes up much of your body and is utterly necessary for your life to continue, in common with all other living things.

"I can agree that concrete should last longer if we can find other materials to reinforce it with that aren't so subject to rust."

Reinforcement of concrete by steel isn't solely a matter of mechanical interlocking, although that is some of it. It also involves bonding of the steel to the concrete. Like all the detail of concrete chemistry, this phenomenon is "poorly understood", but it would stagger me if non-inertness of the rebar was not an important factor, which would make inert rebar potentially less of a useful idea.

I haven't encountered this plastic-coated rebar you mention. It sounds more like marketing than engineering at first impression: looks like it won't rust, but does if there's a pinhole, and spaces the rebar from the concrete with a layer of lubricant to spoil the mechanical interlocking. Domestic and light commercial application for which "longevity" is mostly of puff value, but not, I would think, for bridges and stuff.

The thing is to "reinforce" it not with physical means but with concepts. Compressive architecture, instead of trying to force it to behave in a way opposite to its nature. This is what the Romans did: they treated it as another kind of stone, one which could be shaped by making it go temporarily runny. Depending on exactly what you were trying to do, sometimes making runny stone was easier than chipping at it. But they did not try and make it think it wasn't stone, so it didn't have a tendency to fall down once the spell wore off.

This is also what Robert McAlpine did with it, originally, which is why Glenfinnan viaduct looks perfectly normal from a distance. Most viaducts used shaped stone or brick to make a hollow structure and then filled up the hole with unshaped stone plus concrete to fill in the gaps. Concrete Bob's idea was basically to not bother with any of the big bits of stone and use runniness to shape the whole thing.

However, none of this is really that important; the difference in timescale for plain vs. reinforced concrete to fall apart is not a lot once you're talking about palaeontology rather than archaeology. In either case what you get is bits of funny-looking stone, possibly with linear enrichments of iron oxide, possibly without. After a bit longer you're down to funny-looking grains of sand, which aren't so easy to spot. Very likely the holes for the foundations last longer than the things that were built on the foundations, too.

So do the quarries. Funny holes in particular kinds of rock that obviously aren't geological. Similarly we can still find mines from the earliest times that humans were digging them, mining non-ferrous ores. More holes. Nothing lasts as long as nothing, apparently.

Radioactivity can last a pretty long time, though, and it goes through things, so it's easier to spot. The Romans tended to cart their local supplies of pozzolan all over their empire to make concrete things with, there never being anything local that was as good, and I'm pretty sure that since it is of volcanic origin it has a radiological signature which makes it stand out from a sedimentary environment.

Of course once a civilisation starts using nuclear technology, you get loads of this sort of thing, and it leaves traces that can remain as long as the planet does, the half-lives of uranium isotopes being what they are - or even "artificial" isotopes; there are still detectable traces of primordial plutonium about if you look hard enough. Moz's nuclear submarine will stand out like a sore prick.

Ah, you need to read some more Neal Stephenson :)

Ionic chlorine is as you describe, but organochlorine compounds - where chlorine is covalently bonded to carbon atoms - are often a bit too interesting for complex biochemical systems. The reactivity conferred by the halogen substituent means you get a molecule which looks fairly "normal" to the biochemical eye but does unexpected things when you treat it as such, so it's a kind of booby trap. Many drug variants are potentiated by gluing a halogen or pseudohalogen on somewhere, but plain toxicity is the more likely result in the general case.

(Quite a few elements are a bit like this. Mercury is a fairly familiar example round here...)

Having said that, microbes tend to be fast and inventive in exploring the possibility space of a new bit of chemistry, so if there's a possible reaction kicking around for long enough, some beastie will sooner or later start to eat it. PVC is pretty inert most of the time, but not always, and the embodied energy is there; maybe nothing has figured it out yet, but it will eventually.

Radon vented above roof level? Presumably thats actively pumped then because radon is much denser than air. Is that right?

Cultures that like shiny things ought to leave traces that last a very long time.

Gold remains uncombined over geological time, so it's easy to see it if there's any about just by looking, no chemistry required. Hence humans have been digging it up to make shiny things for a very long time; and the things are just as inert as the original deposit was.

It also makes a heck of a mess in relation to the amount extracted. Stripped-out placer deposits covered over by subsequent deposition are the kind of thing I can imagine some far future geologist noticing in a cliff or cutting side and thinking "this looks funny..."

Where is all this radon coming from? I thought Denmark was about as sedimentary and unmineralised as you got. Is there a lost civilisation's uranium refinery underneath all those kilometres of ancient mud?

"Birds would have more trouble, as it's a task made much easier by having multiple manipulators; they tend to top out at one beak and one grasping foot."

They don't care.

http://www.duskyswondersite.com/wp-content/uploads/2015/02/bird-Weaver-bird-building-nest.jpg

(Also, from the same Bing search, I discover: "What does a weaver bird do?
They write new content and verify and edit content received from contributors." Seems they're even more remarkable than I thought.)

I’ve really got to introduce a useful term here:

Ichnology, which is the study of “trace fossils.”

Trace fossils are preserved tracks, bite marks, butt prints, and especially burrows and holes. Obviously there’s a huge overlap between ichnology and modern tracking and forensics.

Books by Anthony Martin, like Dinosaurs Without Bones and my favorite, The Evolution Underground are good popular science introductions to this field. The second book does get into human ichnology.

Basically, when we’re talking about what traces a paleo human or pre human society would leave behind, we’re talking about ichnology. It’s probably easier to bring it into the discussion, rather than trying to reinvent it on an ad hoc basis.

Besides, Doc Martin is a good writer with a sense of humor, and The Evollution Underground is fun to read.

The radon production per cubic meter depends only on the number of uranium atoms, a glacier grinding a rock to gravel or clay sized particles will not change that.

In terms of radon per square meter clay is often worse than bedroc, because it is much easier for the radon to find a way up and out.

It looks a bit to me as if it is having abnormal difficulty maintaining altitude; I would have tried to pick it up and see what kind of health it was in.

»Radon vented above roof level? Presumably thats actively pumped then because radon is much denser than air. Is that right?«

No, it is just a passive pressure equalization thing: Wind blowing past the hood on the roof creates enough under-pressure to void radon getting pushed through 10cm of poured concrete.

Works a treat, we have the same background radiation inside and outside.

»Er, chlorine makes up much of your body and is utterly necessary for your life to continue, in common with all other living things.«

Absolutely, and that is precisely why nothing wants to have 30% of it in their diet, in particular not if they have to spend a lot of energy pulling it out of a polymer-mesh.

Sharp spiky pozzolan sounds like sometihng worth mining from the Moon or assorted other space rocks. Mind you, it's spiky enough that it might be hard to keep machinery running for long.

And as for old housing, I've stayed in 700+ y.o. houses. The buildings surrounding what was my local cathedral (Winchester, almost 1000y.o.) are largely 800 y.o. and still in use The cathedral is, as you'd expect, mostly stone, and the assorted outbuildings primarily Oak timber-framed buildings. This is one of the reasons I built a timber-frame house, hoping it might have a chance of lasting 400 years. Of course, since it seems increasingly likey humanity won't last that much longer I might have over-shot.

The intent with what I guess must be called 'modern timber frame' is to make something with long-lasting flexibilty so that making alterations for new uses and needs doesn't require total replacement. The basic structure leaves the interior almost totally open structurally, so dividing the space can be done without major work. You could, for example, remove all the interior walls and even the mid-floor, to make a totally open church-like (or theatre) space.

Continent-wide mycelia….a

Doctor Buzzkill here. Former mycorrhizast.

It won’t work, unfortunately. What they don’t tell you in stories about the Wood Wide Web is that the signals they track move at a rate of a few centimeters per day. The proposed system, even if it existed and could jump rivers, it’s way too slow to control animals directly.

Second problem is that most mycelia are only a few centimeters across, and the hyphae that they’re made from generally don’t last very long. When we talk about things like giant honey mushroom clones like the Humungous Fungus, what we’re talking about is aerial evidence of an area of trees infected by a pathogen (it looks just like. Human ringworm, only much bigger), AND all the honey mushroom fruiting bodies collected within the infected area are clones of each other. Proving they’re all interconnected at one point in time is impossible, and it’s quite likely they aren’t. They don’t need to be connected to cause the observed patterns.

Third problem is that it’s unclear that the large scale fungi were talking about started evolving in the Jurassic or. Cretaceous, but they didn’t start taking over the temperate zones until the Cenozoic. The plants that bore the brunt of dinosaurs all grew with tiny little arbuscular mycorrhizae, if they were mycorrhizal at all.

Hmm. There are extreme halophiles which might be able to to tolerate that level of chlorine, if they could get enough alkali to neutralise it. Might. Further research is needed ....

https://en.wikipedia.org/wiki/Haloarchaea

»This is one of the reasons I built a timber-frame house«

Did you study climate model outputs for your local geography first ?

"Hot(er)&Humid(er)" is not at good outlook for wood as a construction material, and one really needs to know the (outlook for) the local geography to decide: Norway and Germany have many very old structures built entirely from wood, but we have nothing like that in Denmark.

I totally agree with you about making the building flexible. You can knock down all interior walls in our house, except for two, without impacting the mechanics of the house, and you even get to decide which two you leave behind.

are often a bit too interesting for complex biochemical systems

Yes, but over geological time, within a tenth to a whole billion years or so, a GRB or a nearby supernova will trash the ozone layer for a century or two, allowing short wavelength UV to get all the way to the surface, at which point photocatalytic depolymerization will get one hell of a leg up.

In the long run, the only signal we leave that will remain detectable will be exotic isotopes. (Which might be handwaved away by a sufficiently blinkered nonhuman successor intelligence as weird-ass nearby supernova bukkake.)

All very interesting, but the post I was replying to didn't say anything about that. It just said living things can't process chlorine. I just pointed out that they can.

The thing I think about is antibiotic resistance, which shows up in all sorts of random places, among prokaryotes not exposed to the antibiotic in question. What seems to be happening is that prokaryotes do all sorts of weird chemistry, including eating electrons off gold. And some of what they do denatures antibiotics, just at random.

I'd expect similar things to happen eventually to break down most halogenated hydrocarbons. It's just a matter of matter of the right bug (or fungus, or fungus with prokaryote symbiont, or...) finding the substrate and getting to work on it.

The confusion here is of course between ionic chlorine (in sodium chloride, aka saline, which we run on) and covalently-bonded chlorine in organic polymers, which we emphatically do not.

Absolutely, and that is precisely why nothing wants to have 30% of it in their diet, in particular not if they have to spend a lot of energy pulling it out of a polymer-mesh.

I don't see the relevance of that. First of course bacteria don't have "wants" so far as we know. They merely evolve over time. I think that you may be underestimating the power of natural selection working across eons.

Which the post to which I originally replied did not mention.

Whether any of the extremophiles can handle it is less clear, though. Some of them have strange tolerances that they did not evolve to handle but, by biochemical chance, they can. Maybe. I am not going to bet on it, but I hope that someone is looking into it.

Did you study climate model outputs for your local geography first ?

"Hot(er)&Humid(er)" is not at good outlook for wood as a construction material, [...]

But is that what Denmark and England might expect from global warming?

I'd read that counter-intuitively, rising temperatures would led to the lose of the glaciers in Greenland switching off the North Atlantic Drift which is driven by fresh water being added to the sea by those glaciers.

The last time the NAD switched off (circa 20,000 BC) it did so in a period of just ten years and led to an annual temperature drop of 16C and a return of glaciers as far south as Potters Bar (12 miles north of London).

Prior to that we had hippos serenely bathing in the Thames.

... or so I read. Happy for corrections from better informed commentators.

Doctor Buzzkill here. Former mycorrhizast.

Slight thread-diversion here, but do you happen to have any pointers to the original fungus that started living out of water? Attenborough's final nature series had a little nod towards a twenty foot high funghi living on land prior to animals getting a foothold.

Unfortunately, I didn't jot down a name, nor would I know where to look for further details.

Thanks in advance.

You may be referring to the Younger Dryas, which did cause a rapid temperature decline and further glacial advance, around 12.9 kyr.

However, before the Younger Dryas kicked off, what would eventually become the UK was still a periglacial area - so tundra / taiga, or boreal forest.

To get hippos, I think you'd have to go back to the Pliocene.

It is not hard to imagine social pressures in a relatively advanced civilization causing its members to hide their traces as best they can. Not our social structure at all, but there are many possible options - status being earned or retained by how hard your people are to find? Ancestors are respectfully incinerated, bones pounded to dust and spread across the landscape, their tools smashed and homes returned to a natural state...

Such a society might well be sustainable for a very long time, and would be almost impossible to detect in deep time. Surely someone would have missed something (or died in an accident and not been recovered), but then a later civilization has to find it and understand what it might be or imply.

It is not hard to imagine social pressures in a relatively advanced civilization causing its members to hide their traces as best they can. Not our social structure at all, but there are many possible options - status being earned or retained by how hard your people are to find?

I find it very hard to imagine. Specifically, to imagine how it came to exist. "Society" means cooperation, and it predates tool usage -- wolves and monkeys have societies and cooperation. Hiding from each other is counterproductive to cooperation.

Where would social pressures like that come from?

so... instead of looking for one anomaly, the trick ought be looking for multiple anomalies grouped closely inside a dense patch of geography... down slope where runoff leads to lumpish deposits... a river valley? downhill from a mountain plateau? run off from London or New Orleans or Mexico City?

not just chlorine, those most toxic elements since chemically they could not break down further... unlikely to have been assembled/concentrated/stockpiled by living organisms the way calcium does into bones and shells...

some horrid accumulation of chlorine + arensic + mercury + ???... suggestive of PVC and treated lumber and fastfood containers and felt hats (along with primitive thermometers) and varied 'n sundry castoffs

dead zones? where nothing grows?

Unfortunately, I didn't jot down a name

prototaxites?

https://en.wikipedia.org/wiki/Prototaxites

"Where would social pressures like that come from?"

While I don't think it very likely, I can think of one possibility.

The society is descended from slaves, whose masters wiped themselves out in internecine warfare or the like, but while the masters were still around, keeping a low profile was an essential survival tactic, that hung on long after its rationale vanished.

JHomes

Adding, of course, you then have to wonder what happened to the traces of the masters' society. While there are possible answers, it is all very unlikely.

JHomes

JHomes 168:

"traces of the masters' society"

perhaps seeking to bury the memories of horrid slavery as well to turn their ex-masters into dust...

Jews hold to repeating the names of our dead as means of keeping them and our memories of them alive... that... inverted

could some prior civilization destroy anything used as virtualized chains to keep 'em slaves?

then there's backlash in response to all the ugly potential of 'unblinking eye' of a monitoring heavy society... in a century will Americans deliberately crush all those doorbell cameras and refuse to purchase any mobile device with built-in cameras?

Jews hold to repeating the names of our dead as means of keeping them and our memories of them alive... that... inverted

suppose that's why people want to rename asperger's autism spectrum disorder

doesn't really roll off the tongue tho

It is not hard to imagine social pressures in a relatively advanced civilization causing its members to hide their traces as best they can. Not our social structure at all, but there are many possible options - status being earned or retained by how hard your people are to find?...I find it very hard to imagine. Specifically, to imagine how it came to exist. "Society" means cooperation, and it predates tool usage -- wolves and monkeys have societies and cooperation. Hiding from each other is counterproductive to cooperation....Where would social pressures like that come from?

Genocidal encounters with white settlers and other violent types will do it. Witness the Yahi, of which Ishi was the last member. A number of forest peoples in Amazonia and Southeast Asia were former farmers who fled violence and disease. IIRC there have been several Australian groups to come in out of the desert, and Papuan tribes coming off the slopes.

Then there's the Mlabri (look them up).

James C Scott's The Art of Not Being Governed gets into this a bit. So, on a different line, does Corbett's Goatwalking.

As you might imagine from someone who wrote The Ghosts of Deep Time, this is something I've thought about. The ghosts in my book were simply trying to keep people in our time from finding out that time travel was possible, to avoid both an influx of colonists and the paradoxes they'd inevitably cause.

causing its members to hide their traces as best they can. Not our social structure at all

Australia suggests that just having an unrecognisable civilisation might be enough to "hide" it. Yez wandering along happily admiring the view and settle somewhere, appreciating the fertile soil but not noticing the profusion of edible plants and expressing frustration that the wildlife are so gun-shy, never realising you're in the middle of someone's farm. When this is pointed out yez starts shooting the homind wildlife that's getting all pointy because that's easier to understand than how this funny-looking countryside works.

Was chatting to someone today and reminded of two things:

• one of the goals of activism is to be forgotten. You want kids to grow up taking your activism for granted and assuming the world was always like that. Especially the children of your opponents.

• politicsa varies dramatically over quite short scales. The gap between the "British" culture of Aotearoa and the "British" culture of Australia is vast at times. Trying to explain to an Australian that there exists a first nations person widely who is both powerful and widely respected even by their opponents can be surprisingly hard, since Australia does not really have a place for anyone like that (the Queen?), let alone a frist nations person.

So "the Australian equivalent of Tipene O'Regan" can't exist. Let alone Titewhai Harawera. "someone who is, like, the head of a billion-dollar corporation, but also an activist in the using-laws activist sense, and also first nations"... as if the head of the Red Cross was also a campaigner for cannibis legalisation while being a respected part of the business community.

»But is that what Denmark and England might expect from global warming?«

Pretty much.

Air holds supralinearly more water vapour as temperature rises and for many biological processes it is the absolute (as in g/m³) rather than relative (%RH) humidity which matters.

suppose that's why people want to rename asperger's autism spectrum disorder

No, it's because it turns out that Hans Asperger was an active Nazi and took part in Aktion T4 (a campaign of mass murder of the disabled and incurably sick, including autistic people).

Meanwhile ... & talking of dangers to civilisation(s)
Covid is back - Though it never actually "went away"
The really worrying emerging data is that the long-term effects of "long covid" are really unpleasant, especially for the lungs & circuatory system.

if we're really serious about looking for 'lost civilizations' then we also have to ask what wrecked 'em... disease, unending war (conventional), war (nuclear), famine, drought, toxins, angst (philosophical decline), abandonment of nursery world (h/t ACClarke Childhood's End), et al

because in each case what gets left behind would differ... as one example... if there was a set of nearly identically sized almost perfectly circular lakes then I'd bet a dollar on either asteroid impacts or a cup of instant breakfast sunshine with raisins and plutonium or a mix of both...

yeah, i think that's what howard meant by "inverted"

Since we're in SF-land, how about a civilisation derived from "prey-species" (I so don't like that term...) which used to survive by hiding from predators. It could stay as a cultural trait well after said predators have been throughly eliminated. It wouldn't be about hiding from each other but from any other species, with pretty much the same result.

Note that "The lost fleet" series has a alien race that seems to behave just like that.

Worth knowing. I just have underfloor venting to the outside that can allow a through draft.

We're on chalk here but I keep the cover tight on the 60 foot well under the utility room floor (yep, sounds daft but its there - complete with lighting and spiders).

Something that crossed my desk yesterday:

https://www.sciencealert.com/plant-fungus-infected-a-human-in-first-reported-case-of-its-kind

Frank has probably seen this, but I thought I'd mention it in case anyone else is interested.

And Greg, something to think about as you putter in your allotment… :-)

Rbt Prior
Nothing as subtle as "sliver-Leaf" Iim afraid, but I did find a real nasty, just last week.
And I can now see how some people fall for it & die, because they don't check.
This one - Amanita virosa / "Destroying Angel" - white (rather than cream) on top & - oops- white UNDERNEATH ...
Wash your hands, carefully, if you've touched it.

just as soon as I read "plant-fungus-infected-a-human" immediately my gut hunch is "Florida"

where else to expect something so unwholesome?

which for those not familiar with the USA, is where we attempt to warehouse as many of our least rational citizens: flat-earthers, anti-vaxxers, inbred politicians of a deviant Republican bent (the Bush clan as prime example so too Ron "Burn-all-books" DeSantis), bible thumpers eager to turn back the clock to the '50s (1850s not 1950s), et al

As with the two other lethal British Amanita species. The amount transferred by touch is unlikely to kill you, even if you lick your fingers, as the LD-50 is of the order of 1-2 grams of fungus (based on rodent models). But it might cause some organ damage even in very low dosage.

where else to expect something so unwholesome?

yeah but it's usually florida man's fault for doing something egregious such as pleasuring himself with a mushroom, this seems to have been an innocent mycologist accidentally inhaling a crafty spore

As the coastline recedes, buying property on a large sandbar is gonna seem kinda dumb...

Similar issues here. Theres no point rebuilding the Westminster Parliament buildings (where we keep our loons and sociopaths), as its probably more cost effective to duplicate it up hill somewhere nearer Trafalger Square. :)

Talking of Materials science & also QM ...
Apparently old news - "massive" quantum superposition in an object totalling 16 μg - which is a lot.
Linkie HERE

Whilst we are on the subject of "wierd" ...
And also, apparently "old news"
Time Crystals - linked - next question ... does this have possible implications for the possibilities, or not, of "ftl" ??

My thought was also a species that was obliged to hide from others. That might also provide the benefits of cooperation while providing social status from ability to cover your traces.

Somewhat implausible, but then so is every other civilization.

Random SF thought - a lot of evolution and gene changes happens with viral infection. The most successful viruses manage to insert themselves into the DNA of host species and replicate into the future. Is it possible that there is (or was) a virus that triggers the capacity for complex thought, empathy and cooperation? Is it then also possible it could infect other species (and maybe has?).

There is a fun dystopian sf short story in the concept of poor waste management resulting in hundreds of millions of farm animals being infected with complex thought and cooperation, looking at their situation, and making a plan. Zero points if it is a critique of the USSR.

There is a fun dystopian sf short story in the concept of poor waste management resulting in hundreds of millions of farm animals being infected with complex thought and cooperation, looking at their situation, and making a plan. Zero points if it is a critique of the USSR.

You are looking for "Our Neural Chernobyl" by Bruce Sterling. HTH. (It's not just farm animals: his raccoons are ... disturbing.)

Not quite on the poor waste management lines, but in "Learning The World" by Ken MacLeod the local chimp/gorilla equivalent species are used for simple heavy labour by the Alien Space Bats. A nanotech infection intended to let the crew of the starship "But The Sky, My Lady! The Sky!" eavesdrop on the ASB civilization gets nobbled by a crew faction and does the intelligence boosting thing...

Oh, but it did. PHK was talking about the resistance to biodegradation of PVC, which is a covalently-bonded chlorine compound. Your attempted refutation was to cite the large amount of ionic chlorine in organic seawater. What we are trying to point out to you is that the chemistry of the two cases is of two distinct kinds, and on this account the vital nature of ionic chlorine in organic seawater has nothing to say, either way, about how easy it is for biochemical systems to metabolise covalent organochlorine compounds.

Organochlorine compounds are useful laboratory reagents but for roughly the same reasons are not easy for natural biochemistry to handle, and accordingly evolution has largely declined to work with them; very little in nature produces them, and so there has been no call for anything to figure out how to eat them either. I agree with Heteromeles that now that human activities have produced them in large amounts, something or other will figure it out eventually, but the number of obstacles that need to be randomly jumped is such that it hasn't happened yet (AFAIK).

One route that does strike me as possible - though since I'm looking mainly from a teleological engineering viewpoint, rather than a random evolutionary one, I have little idea how likely it is - and also of potential narrative interest, would be for some beastie to notice that degradation of PVC tends to produce hydrochloric acid, and this in turn provides hydrogen ions that can scarf electrons off things while the beastie taps the energy produced. There already are extremophilic beasties that do more or less this with sulphuric acid in pyritic ore bodies (and the metabolically significant part is "acid", rather than "sulphuric"). It would not be a case of the beastie digesting PVC directly, but of it exuding some catalyst to encourage its breakdown and then eating the electron transfers in the altered local environment. And of course rather a lot of PVC is used as a covering for metallic copper, so the other end of the electron transfer apparatus is right there where the beastie wants it.

It's always worth checking out mycoremediation, e.g. https://www.sciencedirect.com/science/article/pii/S2215017X19307003 . Fungi live to degrade stuff.

Incidentally, the apparent reason mycoremediation hasn't taken off in the US is that Battelle owns some broad and sloppy patents on the idea. A lot of people like the idea, but so far few have liked it enough to challenge the patents. Sick transit gloria fungi (/bad pun). Otherwise, a lot more people would be following Stamets' trail of developing fungal strain libraries, growing them out on contaminated substrates under lab conditions, and licensing out the best growers.

I think crabs are it, the tree octopus needing high humidity and an absence of its specialised predator to really thrive. Maybe an echinoderm (heavy duty climbing starfish, tree urchin? ). My favourite possibility would be mangrove crabs, which reverse the usual crustacean "hide under something" escape reflex. I knew someone who left the lid off the tank and found a dozen of them clinging to the ceiling in the morning. On the plus side if you drop one they will run up your leg and try to hide on top of your head, so they're easy to catch.

The big problem for anything living on land is that rain is freshwater. A large number of marine organisms are stuck in the ocean because they never evolved tolerance to freshwater. This group includes, unfortunately, all cephalopods and echinoderms.

I wrote a short story, "Sandtrap", published in Interzone 187 in 2003, based on this sort of theme: explorers dealing with the implications of the necessarily limited evidence of a technological civilisation a billion years after its demise.

http://www.nawaller.com/site/sandtrap.html , where you can read the story in html or pdf.

Not in a formal way, but I thought of my "Enta Geweorc", a 2004 short story in Interzone 195 in 2004, as a billion-year prequel. http://www.nawaller.com/ for that, a few other other IZ and one or two other stories. My site was designed in 2006 so is showing its age a bit.

I don't understand what people have against woodlemice (*), er, woodlice. One species has adapted to even semi-desert. Crabs are mere wimps by comparison.

I find them useful in the garden - if the compost heap is grey with them, it's too dry :-)

(*) As one daughter called them when she was very young.

what could be derived from studying invasive species as after-effect of technological civilization? not much is my guess, but...

here's some fast-reading context:

https://lite.cnn.com/2023/09/24/opinions/invasive-species-spotted-lanternflies-climate-un-report-larson/index.html

the less I think of kudzu, the easier I can sleep... especially as the increasing temperatures ever northwards are going to provide those fracking vines with an expanded growth zone and therefore challenge ecological niches already under stress

there's a shit-ton heaping of concern here in New York City since we're both a seaport with three mega-airports and a zillion bridges/tunnels to 'mainland' North America...

we are seeing evolution in action (at a much accelerated paces than in the wild) as rodents gain not so much enhanced brains as refined tastes and a habituated behavior of take out food as opposed to homecooking

https://www.youtube.com/watch?v=xvs8zGLJe-U

Howard NYC @ 176:

if we're really serious about looking for 'lost civilizations' then we also have to ask what wrecked 'em... disease, unending war (conventional), war (nuclear), famine, drought, toxins, angst (philosophical decline), abandonment of nursery world (h/t ACClarke Childhood's End), et al

because in each case what gets left behind would differ... as one example... if there was a set of nearly identically sized almost perfectly circular lakes then I'd bet a dollar on either asteroid impacts or a cup of instant breakfast sunshine with raisins and plutonium or a mix of both...

Carolina Bays

Pigeon @ 138:

"I can agree that concrete should last longer if we can find other materials to reinforce it with that aren't so subject to rust."

Reinforcement of concrete by steel isn't solely a matter of mechanical interlocking, although that is some of it. It also involves bonding of the steel to the concrete. Like all the detail of concrete chemistry, this phenomenon is "poorly understood", but it would stagger me if non-inertness of the rebar was not an important factor, which would make inert rebar potentially less of a useful idea.

I haven't encountered this plastic-coated rebar you mention. It sounds more like marketing than engineering at first impression: looks like it won't rust, but does if there's a pinhole, and spaces the rebar from the concrete with a layer of lubricant to spoil the mechanical interlocking. Domestic and light commercial application for which "longevity" is mostly of puff value, but not, I would think, for bridges and stuff.

I didn't mention it. Someone else did.

I've not encountered it either, probably because it hadn't been widely introduced 40+ years ago when I was an iron-worker.

I'm not an engineer, but I can read a blueprint and set up a rebar framework for a poured structure ... including making the required bends (as per the blueprint & schedule) in the rebar. I know how to assemble forms and place the rebar into forms so that it's not exposed to the air after the concrete poured.

And I know how to pour concrete into forms so that there are no unacceptable voids exposing the rebar.

Don't know if the work I did will last eons or what traces will still be detectable millions of years for now, but it should be strong enough to last several thousand years (at least as long as Roman aqueducts ...).

I should think scientists & archeologists from some future race would probably figure out what caused oddly uniform aggregate rocks with strange linear veins of iron oxide running through them to form ...

Grant @ 140:

Radon vented above roof level? Presumably thats actively pumped then because radon is much denser than air. Is that right?

At my old house, THEY advised me to have my basement periodically tested for Radon, but never told me to have the attic tested.

I don't understand what people have against woodlemice (), er, woodlice. One species has adapted to even semi-desert. Crabs are mere wimps by comparison.*

I've got nothing against woodlemice (nice name!). Charlie's the one who has terrestrial isopods eating people's tongues and castrating people...

if we're really serious about looking for 'lost civilizations' then we also have to ask what wrecked 'em...

How about Milankovitch Cycles? ( https://en.wikipedia.org/wiki/Milankovitch_cycles Check out the mean Q^day graph in https://upload.wikimedia.org/wikipedia/commons/5/53/MilankovitchCyclesOrbitandCores.png )

IUI, basically Earth's climate normally goes boingie boingie between alternate stable states, spending about 2000 years going "boing" in relative stability, and "Iiieee" for around 9200 years as the climate slowly and inexorably swings to the other extrene but stable state.

The boings are when it might be worth trying agriculture and risking your future on a few stable crops. The periods of change favor landscape management with fire (if possible), being nomadic, and diversifying your diet so that you can always find something to eat.

Such cycles happen whether or not the Earth's in Hothouse or Icehouse mode, according to really good geologic data which has picked up signals of the swings going back into the Paleozoic.

We currently live in a time of unusual stability, the first one in about 400,000 years. I'm one of the people who think that long-term stability is why we have civilization now, because civilization is built on having a relatively predictable environment that allows you (if you're brash) to feed a lot more people than an unpredictable climate does. If we weren't busy fracking the climate right now, we'd have about 40,000 more years to build a really high civilization before the climate seriously started cycling again and took it down.

Anyway, 2000 years is long enough to start experimenting with settled villages, domesticate crops, and get serious about the whole "gods love us and want us to be fruitful and multiply" thing, before the inevitable climate changes forced the survivors of the exuberance back to the Old Ways.

No need to invoke a special civilization killer when human stupidity and baked-in wobbliness in Earth's orbital parameters will do just fine, and probably have.

I have never been convinced that Milankovitch Cycles are real and not just a curve fitting artifact with noisy input data.

NB I am not stating that they are not real, just that I'm pretty sure I could take the same data and fit just about anything.

"Pushing Back"
How does one account, then for This total insanity in Michigan? - I mean people are loopy & uneducated enough to VOTE for these loonies?
Can someone from the USA please explain?

Late to the party, but this reminded me of a Kurzgesagt video on this very subject (https://www.youtube.com/watch?v=KRvv0QdruMQ).

It's very pop-science, but vetted by specialists, and they do provide links to the academic papers the video is based on.

The bottom line is the further you go back the more difficult spotting a human-style tech culture is, so we have to real way of telling if such civilisations existed in deep time (but is good evidence indicating such civilisations did not exist in the last few million years).

My personal feeling is that the best chance we'll have for spotting silurians will be if they've left crap cluttering up the moon...

Greg Tingey @ 203:

Can someone from the USA please explain?

Some people are even crazier than you or I. Some other people are evil enough to try to take advantage of it.

Greg Tingey @ 203: Can someone from the USA please explain?

There's the rage at anyone else doing better than they are; whether winning the birth lottery to born into vast wealth, or being talented enough to sing well, or kick/toss balls for a million bucks, they are angry. But what seems to be pissing off so many 'conservatives' in rural areas in the USA are all those millions of people who by way of hard-hard-hard work quietly made themselves well off.

You know, the nerds who got laughed at in high school and never got laid. Girls who focused on studying and ignored makeup tutorials, getting into decent colleges and establishing themselves in difficult careers. Boys who skipped sports and learned about science or math of computers. Lawyers. Doctors. Engineers. Dentists. Some of whom got mega-wealthy but 99 of 100 do not have gigabucks; having achieved a nice house, a nice car, a nice retirement plan, are now envied. Loathed. Ought be hanged for being sneaky, cheating by way of intellect and sacrifice and education.

Nerds.

Whereas those who slacked off in high school are looking around, twenty years post-graduation and realizing "whoooooopisie!" and not willing to blame themselves are seeking anyone to blame (cough, cough, trans kids, gays, blacks, uppity women, and of course Jews) and looking everywhere for support of their paranoia-conspiracies-scapegoating.

Welcome to the twentieth-first century.

Just like the nineteenth but with indoor plumbing and an unending shit-spewing stream of social media platforms. So, add it all up... climate change + restless minorities + failing medical services + GOP fadeout + fossil fuel megacorps under pressure + world wide access to communications like no other generation ==> cyber-based organizational fascism. Or as T(he)Rump boasts as most favorite, most successful of his four children, "MAGA politics".

Only thing missing to complete this ratfuckery is Soylent Green™ on our store shelves in convenient 15.5 ounce tin cans.

What a lot of people miss is that feedback systems (even linear ones) can produce anything from definite periodicity to irregular patterns that look like cycles over short periods but aren't, depending on the parameters. In particular, you can extrapolate periodic systems fairly reliably, but cannot do so for the other patterns. Sunspots are the classic example. Those pictures of Milankovitch cycles are exactly what you expect, and I would need to analyse the numbers carefully to even guess which are genuinely periodic and which aren't. And, of course, such systems often have different characteristics over different timescales.

Didn't read the article, either of you?

The Milankovitch Cycles aren't feedback systems, they're orbital wobbles. Basically, the Earth is a not quite spherical, spinning, orbiting in a not-quite circular ellipse, and getting gravitationally yanked on by Jupiter (the Moon and Sun tend to stabilize things). So it wobbles.

The wobbles are fairly cyclic. They are in orbital eccentricity (ca. 100,000 years), axial tilt (ca. 41,000 years), axial precession (ca. 25,700 years), apsidal precession (ca. 112,000 years), and orbital inclination (ca 70,000 years).

There's also pretty good evidence, both in geology and in astronomy, for the existence of the cycles and their effects on Earth's climate. One signal, seen repeated going back IIRC hundreds of millions of years, are shallow lakes that cyclically dry up and reflood with a periodicity of tens of thousands of years. The details of the cycles do vary over tens to hundreds of millions of years, but there are cycles.

The point about the cycles and civilization is that, starting around 8,000 years ago and lasting for another ca. 40,000 years, we're in an anomalously average time when, by coincidence, every cycle is at a point where things don't change much year to year or even decade to decade. That's one reason it's an interglacial. This predictability makes agriculture possible, which makes civilizations possible. The last time a period like this happened was around 400,000 years ago, so this is the first time our species has seen such stability. This is a good hypothesis for why large civilizations are happening now and not 112,000 years ago, when it was equally warm (Eemian) but much more unpredictable year to year. As OGH noted, there's increasing evidence that our ancestors were as smart and capable as we are. Why didn't they become civilized? Well...maybe they simply lived at a time when civilization was infeasible?

I mention the mass-less neutrinos, because nuclear reactors emit a LOT of antineutrinos, but since everybody "knew" they were mass-less and therefore didn't interact with matter, any report about living close to nuclear reactors at best mentioned them in a footnote, saying they "went straight through everything without doing any kind damage".

That's... pretty confused. Theoretical studies of neutrino oscillations -- which require that neutrinos have mass -- go back to the 1960s (late 1950s, really), and there were active experimental programs looking for signatures of possible neutrino mass starting back in the 1980s. (And arguments about neutrino oscillations explaining the observed deficit in solar neutrinos.) So, the idea that neutrinos were massless was not "dogma" suppressing other thought or research.

And the fact that neutrinos barely interact with ordinary matter at all has nothing to do with their having or not having mass. (Photons are massless, and they can certainly interact with ordinary matter!)

Sigh. Orbital mechanics IS a feedback system, and N-body effects (which those are) are generally not truly periodic, and are sometimes chaotic. Some of those variations look like well-behaved cyclicity, but others don't.

The reason that this matters is predicting the future. Some of those characteristics can be predicted a long time ahead, but others can't. The best you can say for those is that there will be variation of an approximately cyclic form, but won't be able to predict the phase beyond a short time ahead.

The class example is where the earth will be a million years hence - i.e. we can predict the orbit (black swan events excluded), but not where it will be on it.

I have never been convinced that Milankovitch Cycles are real and not just a curve fitting artifact with noisy input data.

They're not "curves fit to data". They're predictions from celestial mechanics: how the Earth's orientation and orbit change over time due to the gravitational influences of the Sun, Moon, Jupiter, and Saturn (with weaker influences from other planets).

Semantics, and I think we mostly agree. To me, gravity isn’t so much a feedback because everything’s both emitting and responding to gravity waves simultaneously, not sequentially, which is to me how feedback works. You disagree in a reasonable way, and that’s fine with me.

To me, the bigger point is about humans. It’s a reasonably good argument that it’s worth assuming that hominids were (and people are), pretty equivalent in our abilities, albeit diverse. It’s also worth assuming that lineages like the Neanderthals disappeared, not because they were inferior, but because they were too close to a large supervolcano and died along with all the moderns and Denisovans in the same area. It’s also worth assuming that our predecessors didn’t form civilizations because the constantly changing climates they faced made this maladaptive. This may seem weird, but if you’re complaining about the idiots running the show now, you’re also saying that intelligence is not necessary for civilization to work.

Note these are all disprovable. They’re uncomfortable, not because there obviously wrong, but because they imply that we’re here, not because we’re superior, but because we’re luckier. And, especially in a racist society, that can be hard to swallow.

What about truffles? The huge part underground? Or some trees, that communicate through roots?

You forgot nearby novas or (Ghu) supernovas.

The majority, I think, were jocks, were the "popular kids" in high school, and never got over no one else caring after they were out of high school.

And there's the absolute fear, that they don't want to admit to themselves, that some, if not most, of the "unpopular kids" in high school actually are competent, and they, themselves, are crap at work.

So-called 'nerd resentment' of people from their high school is fun to indulge in once in awhile, but hardly reflects the multigenerational impact of systemic poverty, enculturated racism and (in the US specific case) the large scale gutting of the manufacturing sector.

You are also falling victim to the 'meritocracy' bullshit that is such a core element of so many of our problems.

We have relatively anemic education systems that are designed as half 'child warehouse' and half 'worker training', where anyone who is more than one or two standard deviations from various means not fitting in. That's a part of the problem.

A bigger part is the age-old belief by the oligarchs and plutocrats of the current day (modern day aristos and their courtiers) that democracy is inconvenient to them. That is combined with their belief that they can manipulate the masses through fear to achieve their own policy aims.

their belief that they can manipulate the masses through fear to achieve their own policy aims

Empirical evidence shows that this belief is quite realistic

Howard NYC @ 206:

Greg Tingey @ 203: Can someone from the USA please explain?

There's the rage at anyone else doing better than they are; whether winning the birth lottery to born into vast wealth, or being talented enough to sing well, or kick/toss balls for a million bucks, they are angry. But what seems to be pissing off so many 'conservatives' in rural areas in the USA are all those millions of people who by way of hard-hard-hard work quietly made themselves well off.

Did we follow the same link? I got a reddit thread about the "chairwoman" of the Michigan Legislature's GQP chaos caucus telling her critics within the caucus to "pound sand".

I didn't see anything in there about nerd envy (or the revenge of the nerds for that matter).

The relevant aspect is what is described in the "Theory constraints" section of that article. It is debatable whether those factors are a direct cause of temperatures, a forcing oscillation, or simply associated. And I really don't see why stability in them should mean more year-to-year and decade-to-decade stability. I should be interested to see some reasonably direct evidence that we are in a period of unusual stability.

The current belief is that Neanderthals went extinct because of climate change, yes, but being too close to a supervolcano is a new one on me. Why didn't it kill the modern humans who coexisted with them? And where and when was it?

ilya187 @ 217:

their belief that they can manipulate the masses through fear to achieve their own policy aims

Empirical evidence shows that this belief is quite realistic

Realistic? Or merely a currently successful tactic? I say "currently" because it has failed on occasion in the past.

ilya 187 & John S
To enslave the people, it is necessay to APPEAR to wear the same chains as they do

JohnS 218:

my response was in providing background as to what is driving #BSGC and #MAGA and Fourth Reich revival (and KKKlan 4.0 revival) to someone outside of North America...

yes, American education as an industry is deeply flawed and if it was a publicly traded corporation nobody would invest in its common stock nor willingly buy its products... but anybody with raw brains and mule stubbornness can get a decent education and then claw their up 'n out of poverty... just not as often as it used to be... and society at large loathes anyone escaping poverty...

still the bitter circumstance where the following statement is widely shared in USA: my cow stopped giving milk so I blame them Jews

ditto for anyone with a receding hairline or severely overweight or cannot catch the eye of pretty girls or...

or...

or...

because scapegoating is as American as apple pie... that's all necessary background to understand the fracturing politics of the here-n-now...

excuse me whilst I gnaw my way through a wedge of rhubarb cobbler because what I really want is a quart of tequila and dancing the night away to drown my sorrows rather than watch as the world burns for sake of megacorp profits and my fellow Americans howl for my blood because I'm not a Christian... projections are the cost of luxury foodstuffs (cake, chocolate, etc) over the coming years will be 3X baseline inflation...

Realistic? Or merely a currently successful tactic? I say "currently" because it has failed on occasion in the past.

Throughout history, manipulating masses through fear has been an incredibly successful tactic. Part of the reason Thirty Year War was so vicious was because for years prior to it, both Catholics and Protestants were constantly told that the other side was baby-sacrificing monsters. Each side was so murderous because they were terrified of being murdered if they were not. Poor Southern whites went to fight and die in the US Civil War because they were terrified that the blacks would kill them the moment they had a chance. I don't think this tactic ever failed prior to 20th century.

getting back to main theme...

as to motivations for hiding -- thus leaving behind fewer traces of one's existence -- you ought consider what happens when a minority group is being actively hunted by a overly zealous majority

not only might Earth have had its own intelligence species arise, over the prior giga-year plenty of opportunity for a fearful bunch of XTs to land, build a colony and do everything possible to avoid detection... indeed given 10^11 stars in just this one galaxy, we could have had a couple dozen-plus such refugee colonies on Earth, separated by a mere five mega-years... heck... two hundred? two thousand!?

Pushing forward a bit as opposed to back, it looks like in a mere 250myears we’ll be totally out of luck, what with a new Pangea a-building. Guardian article on supercontinent coming soon

Of course the rabid brexshitteers are already gearing up to prevent Global Britain^H Ingurland from having any part of joining this SuperContinent Nonsense.

The current belief is that Neanderthals went extinct because of climate change, yes, but being too close to a supervolcano is a new one on me. Why didn't it kill the modern humans who coexisted with them? And where and when was it?

The Phlegraean Fields big eruption was around 39,300 years ago ( https://en.wikipedia.org/wiki/Phlegraean_Fields ). As the article notes, this eruption has been potentially associated with the disappearance of Neanderthals for awhile.

Newer research on human (H.s.s.) ancient DNA in Europe added a wrinkle to that. They sequenced genomes going back over 45,000 years. The sequences from before the eruption are from a very different population than the ones after the eruption. One way to explain it is that the eruption killed most or all hominids in Europe regardless of species, and Europe was then recolonized from Africa and the Middle East. This would coincide with cultural changes after the eruption, which marks the end of the early paleolithic and the start of the middle paleolithic.

Back to the beginning:

Intelligent dinosaurs: would we be able to detect the imprints of their cities and research hubs? Or, push it forward a few tens of millions of years: what about the giant flightless birds of South America? What if the whales in the sea today are the evolved descendants of a genus that at one time, 40My ago, spawned boat-building tool users and a thalassic civilization that is mostly submerged? How hard would it be to detect an 18th century peak age-of-sail civilization (gunpowder, cast iron cannon, printing presses) at that remove in time?

The big point is that hothouse Earth didn't have large ice sheets until a few million years ago, so ocean levels then were considerably higher than they are now, and shallow epicontinental seas were higher then than they are now. As a result, shoreline ruins from then are likely high and dry now. Moreover, artifacts entombed in fossil reefs would be likely still around. So yes, evidence could survive. Maybe not iron, but worked stone, bronze, and gold might well last.

ilya 187 @ 223
And, the revoting Braverman is at it again - this time cosying up to the US fascists & blaming & scapegoating "refugees".
Who is our modern Sir Nicholas Winton, I wonder? Does she or he even exist?

just having run across this snippet... something a bit fascist about it like mass military parades... I know which American politicians it fits like a glove... so I ask you-all, which UK-NZ-AUS politicians?

“There was nothing he [Louis XV] liked so much as flattery, or, to put it more plainly, adulation. The coarser and clumsier it was, the more he relished it.”

--the Duc de Saint-Simon

Sigh. Orbital mechanics IS a feedback system, and N-body effects (which those are) are generally not truly periodic, and are sometimes chaotic. Some of those variations look like well-behaved cyclicity, but others don't.

Orbital mechanics is generally not a feedback system. In the case of Milankovitch cycles, one could perhaps argue for some vanishingly small feedback on Jupiter's orbital evolution from changes in the eccentricity of the Earth's orbit (and its apsidal precession), but its effect would be meaningless. Precession of the Earth's axis and changes in its obliquity (which are not "N-body effects") would have no meaningful effect at all on the orbit of Jupiter, Saturn, or the Sun.

The Milankovitch cycles have been exhaustively studied since Milankovitch first calculated them in the early 20th Century; they are not chaotic. They will not be perfectly periodic on timescales of tens or hundreds of millions of years; but so what? They're perfectly usable for timescales of a million years or so.

You seem to be saying periodic where you mean predictable. Firstly, if you look at those graphs, even the most regular are not perfectly periodic over ANY scale; they're more complex than that. As far as N-body effects go, Saturn will have an effect on Jupiter's orbit, which will in turn affect the earth's. And the earth, moon and sun are a N-body system as far as the latter two are concerned.

I agree with you that they are PREDICTABLE over millions of years, but the reliability of the predictions drops off rapidly with the time separation.

Interesting. That makes sense. But that was only the final demise of the Neanderthals - they were already an endangered species by then.

Interesting. That makes sense. But that was only the final demise of the Neanderthals - they were already an endangered species by then.

I'm notsure any hominid in Ice Age Europe was ever that common. They seem to have always been more like the Inuit (or wolverines, polar bears, or snow leopards), with total populations across the continent in the tens of thousands, not millions.

In reply to #203 and #206's response, I don’t think it’s so much “nerd resentment” as the fact that once you get away from large cities, the media environment in much of the USA is depauperate, to say the least. I live in western Wyoming and work remotely from south-central Utah for several months out of the year. Both places are very sparsely populated. My home county is about the size of Lancashire + Norfolk, and has about 9,000 inhabitants, while in Utah, the county is the size of Norfolk, and has 2,500 inhabitants. Until recently, internet was spotty, and satellite TV access expensive. This means that most people listen to the radio and watch broadcast TV, to the extent it’s available. Most radio stations have a talk or Christian format. The talk shows are right-wing, while the “Christian” ones spend a lot of time deep in the book of Revelation and asking for donations to prevent godless liberals from crushing “Real America”. I appreciate that my locales are extremely rural, but if you’ve ever driven across the USA and checked out the radio offerings between large cities, it’s very similar. Another reality of rural life is that you spend a lot of time in your car, so that talk radio becomes a habit for many people.

As for TV, many local stations have been bought or are controlled by Sinclair Broadcast Group, which owns or operates 193 stations in 100 markets. As noted in Wikipedia: A 2019 study in the American Political Science Review found that "stations bought by Sinclair reduce coverage of local politics, increase national coverage and move the ideological tone of coverage in a conservative direction relative to other stations operating in the same market." The internet has just exacerbated these trends, as TV and radio hosts provide links for people to follow up on what’s being said over the air, rather than seek out other opinions. As a result, I hear lots of talk about the immigration crisis, Hunter Biden, Joe Biden’s senility, and interesting theories about lost F-35s when I engage my coworkers and neighbors in conversation.

The Wyoming Republican party is now being taken over by MAGA-republicans, who consider anyone who votes against their narrow national agenda to be a RINO (republican in name only), and therefore needs to be voted out of office. They even provide a handy website (https://wyorino.com) where one can see who doesn’t toe the line. Whether a legislator works on local issues matters much less. In an overwhelming republican state that Donald Trump won with 70% of the vote in 2020, only republicans stand a chance of winning most districts. Only the most motivated partisans vote in the primaries, so I don’t see this situation improving over the foreseeable future. Utah, due to its large urban centers and the Church of Latter-Day Saints of Jesus Christ's dislike of Trump, is less extreme, but their legislature worked very hard to gerrymander Salt Lake City into four different congressional districts so that they couldn't elect a democrat to congress.

Slightly off-topic: Charlie, you'll not ba happy to know this: there was a link on last night's FILE 770 to an article in the Atlantic, which lets you search the data dump of books used to train the LLMs, and you're among the authors who's books were stolen and used.

Design comes before construction.

Humanity's first architectural drawing will be forever unknown to us because it was literally written on sand or traced in soft mud. The oldest know site plan is on a granite slab discovered at a 14,000 year old archeological site in Spain. It depicts the layout of a semi-permanent campsite established by neolithic hunter gathers and shows the layout of its grass huts. It predates the oldest know images of buildings by 6,000 years.

Ancient architects achieved levels of genius in their design of Egyptian pyramids, Greek temples and Roman palaces. But not much is known of how they drew their architectural plans. A 3,500 year design of a garden on a painted wood tablet from ancient Egypt is the oldest know dimensioned architectural drawing. These designs must have existed but were probably made on perishable sheets of papyrus or paper (existing Roman architectural designs are either in set in mosaics or carved into marble). There is evidence that the designs were drawn directly onto the building itself as it was being constructed with its floor plan laid out directly into the ground using posts and ropes.

Somewhat related to Deep Time/Far Future matters:

https://www.nature.com/articles/d41586-023-03005-6

Up to 92% of Earth could be uninhabitable to mammals in 250 million years, researchers predict. The planet’s landmasses are expected to form a supercontinent, driving volcanism and increases to carbon dioxide levels that will leave most of its land barren.

“It does seem like life is going to have a bit more of a hard time in the future,” says Hannah Davies, a geologist at the GFZ German Research Centre for Geosciences in Potsdam. “It’s a bit depressing.”

[snip]

This joins the five other models for "Pangea Ultima" and as usual for all of the scenarios, they forget about the effing burrowers.

Burrowers for the win! I also pointed out how humans could survive in this environment in Hot Earth Dreams. You can label it either "Tunnels and Trolls" or "Mole People Rule," if you realize that corn could evolve into a cool season crop in such conditions, and all they have to do is make food stores last through the hot season, it's doable, at least in oases.

"Flintstones! Meet the Flintstones!"

Question: Just how advanced could a purely stone age civilization get?

A civilization forced to work with just stone and wood, vegetative and animal fibers, due to inherent lack of metals in its planetary crust.

A civilization limited to animal and muscle power, wind and water, for transport and industry.

Maybe it wouldn't use an elephant's trunk for hot showers, brontosaurus excavators, photos taken by having a trained bird chisel a likeness, or cars propelled "courtesy of Fred's two feet".

But assuming such a civilization can make glass, optics become available - both the microscope and telescope - leading to advances in medicine and astronomy.

No barrier to developing Newtonian physics, and Einstein's physics started out a thought experiment - so why not a theory of relativity?

IIRC, the tallest non-steel, purely granite, "Skyscraper" ever built was a six story stone office building in Chicago.

More aesthetically, the cathedral at Notre Dame took how high you can build a complicate structure with stone to its physical limits.

All your basic infrastructure (roads, sewers', aqueducts, bridges) can be provided.

Windmills and water wheels can provide industry.

Ships as fast as an American Yankee Clipper or as big as a Ming Chinese treasure ship.

Rail transport, pulled by horse teams either on actual rails or down canals is possible. Canals with locks allowing travel up and down stream can be built.

As for weapons, both Greek Fire and gunpowder are possible - just not metal musket barrels or cannon so their use would be limited to grenades (then again, didn't the Swedish army of Gustavus Adolphus have light cannons with leather barrels, and didn't some medieval bombards use massive hollowed out tree trunks?).

Projectile weapons like cross bows remain possible as do obsidian edged blades and spear points.

Semaphore towers (especially aided by telescopes) can send complicated messages rapidly across a continent in a matter of days.

So... you have everything you need except metals.

How far can your civilization go?

"Wilmaaaaa!"

Haven't read all the comments yet so apologies if this has already been mentioned.

My guess is that simple geometric forms (esp. straight lines) would be a good place to look for ancient habitats. A while back there was an article about how satellite pictures (x-rays?) helped discover Aztec cities in the middle of dense forests - the big clue was the straight lines.

Recent discoveries of considerably less ancient cities in the Mediterranean Sea suggests that we should consider what the world topography/geography/climate was like back in the millennium of interest.

As to how long various materials can survive: I recall reading some time ago that volcanic ash and peat bogs are fairly effective preservatives for organic materials (including flesh) for a few thousand years at least.

Can quipu methods be combined with an abacus layout to create a Stone Age "Difference Engine"?

Of particular interest from a British (or Belgian) viewpoint is that the London Clay deposit is that age, ish (bit older, but never mind). And it preserves all sorts of things, rather well; you get a lot of fossils which retain very good impressions of their original shape. Free iron would go, but its oxide would remain, and still retain interesting amounts of detail of the original shape; less reactive substances would leave correspondingly more. So you certainly ought to be able to identify a fossilised cannon if you were lucky enough to find one, and if you were really lucky you might find a whole ship. And the weapons, and the crew with skeletal deformities from being bred to use them, etc.

Unfortunately it's pretty impossible that preservation of detail would extend to the output of the printing presses, so there wouldn't be any newspapers or orders to tell you directly who they were using the weapons against. Although if there's enough symbolism in common you might get a bit of a clue from the insignia and stuff (it contains fossil beetles that you can see immediately are beetles; you ought to get fossil cap badges, for instance, that are similarly well preserved).

So maybe the real reason Crossrail was so delayed was the thing they dug into that nobody talks about and survives. Or maybe military archaeologists investigating WW1 mining operations could discover that the military reasons for operations in the Ypres salient are really all just post-hoc rationalisations, and the real reason so many people got killed fighting over the shittiest bit of land in Belgium is all to do with the ancient temple buried underneath that bit.

Printing presses, gone? I strongly disagree... given that type is LEAD.

"A civilization forced to work with just stone and wood, vegetative and animal fibers, due to inherent lack of metals in its planetary crust."

I always find these horribly unconvincing. Where are all the metals? There's shitloads of aluminium and calcium in Ordinary Rocks. Iron is basically "what the whole thing's made of" because of the peak of the binding energy curve, so that has to be around, even if it's diffuse; also, lumps of it fall out of the sky, perhaps not very often but often enough that we know people make things out of them. Biochemistry without sodium, potassium and calcium is kind of hard to imagine, too.

You could perhaps argue for lack of "easy" metals, as in concentrated veins of things like copper which are possible to smelt by accident. It is often said that lack of the kind of geological processes which lead to mineralisation would prevent intelligent life evolving; I think rather that while it might prevent it evolving in the manner and timescale of the sole example we actually know about, it would still be possible in general, if a bit slowly and/or weirdly. I see the effect on technological development as being more or less similar; certain paths are not available, but it is still possible - and pretty inevitable, if your intelligences notice chemistry even slightly - to discover aluminium and iron, and once you've got those two sorted out, you're laughing, more or less. And so many of the things you list, while they are certainly possible without metals, are such a heck of a lot easier with metals - even in apparently insignificant amounts - that there's buckets of incentive to develop metals once you do become aware of them.

Heteromeles @ 227:

Back to the beginning:

Intelligent dinosaurs: would we be able to detect the imprints of their cities and research hubs? Or, push it forward a few tens of millions of years: what about the giant flightless birds of South America? What if the whales in the sea today are the evolved descendants of a genus that at one time, 40My ago, spawned boat-building tool users and a thalassic civilization that is mostly submerged? How hard would it be to detect an 18th century peak age-of-sail civilization (gunpowder, cast iron cannon, printing presses) at that remove in time?

The big point is that hothouse Earth didn't have large ice sheets until a few million years ago, so ocean levels then were considerably higher than they are now, and shallow epicontinental seas were higher then than they are now. As a result, shoreline ruins from then are likely high and dry now. Moreover, artifacts entombed in fossil reefs would be likely still around. So yes, evidence could survive. Maybe not iron, but worked stone, bronze, and gold might well last.

I still think the residue of iron materials (i.e. the rust) would be detectable the same way the residue of wood (in the form of fire pits, post holes & middens) are detectable. Even though the iron rusted away the pattern the iron was formed into remains. You don't find the knife, you find a knife shaped pattern of rust. You just gotta' know enough to look.

Also, AFAIK, you can't have iron without iron mining and that too would leave traces if someone was observant enough to see them.

The presses themselves, sure, they would make excellent relics, just as you say. But the output of them - paper with marks on it - not so much. You might find chicken bones where matey lost his packed lunch dropping it in the mud, but you'd not be able to read the headlines off the newspaper he wrapped it in.

Howard NYC @ 229:

just having run across this snippet... something a bit fascist about it like mass military parades... I know which American politicians it fits like a glove... so I ask you-all, which UK-NZ-AUS politicians?

All of them Katie

... including the U.S., Canada, all of Middle & South America, Europe, Asia and Africa, but NOT Antarctica.

"Even though the iron rusted away the pattern the iron was formed into remains. You don't find the knife, you find a knife shaped pattern of rust. You just gotta' know enough to look."

Exactly. Even though the rust itself doesn't stay put, how fast it migrates depends on groundwater and geobiological conditions, so if the deposition entombed it quickly enough in something pretty inert and impermeable, you would at least get a recognisably knife-shaped brown stain left behind. A big thing like a cannon would leave you more, and also not be so dependent on you breaking the lump apart just right to notice it.

239 Para 8 - You don't; the tower of St Martin's Cathedral, Utrecht is 360 feet tall.

Resident_Alien @ 234:

Won't quote extensively or replay a bunch of stuff I mostly agree with, but congratulations on giving me a new word - "depauperate". ... and I thank you for it.

If you're an east coast liberal (like I am), you really need an alternative audio source to accompany you as you while away the miles across the "great empty". I replaced the radio in my Jeep with one that allows me to have mp3 files on a USB drive.

I don't know how long I can go without having to listen to the radio, but it's currently up to 12 "CD-ROMS" of mp3 files (~ 7 hours per CD-ROM equivalent @ 700MB/CD) and the drive is only about 1/4 full. So, maybe 3 days of continuous play.

Plus there IS some coverage from NPR (not quite the BBC*), at least when you get near some of the larger cities on the Interstates.

And as long as you stick to the major hotel chains you can get adequate internet access ... or as adequate as anything can be on a laptop.

• But many of the NPR stations I've heard along the way do broadcast BBC world service news over-night.

DP @ 236:

Design comes before construction.

Sometimes. 😏

DP @ 239:

As for weapons, both Greek Fire and gunpowder are possible - just not metal musket barrels or cannon so their use would be limited to grenades (then again, didn't the Swedish army of Gustavus Adolphus have light cannons with leather barrels, and didn't some medieval bombards use massive hollowed out tree trunks?).

The first rockets were used as propulsion systems for arrows, and may have appeared as early as the 10th century in Song dynasty China.

DP
how high you can build a complicated structure with stone to its physical limits?
Salisbury Cthaedral's spire is 123 meters tall ....

Re: 'It's that the nutrient levels in plants correlate with atmospheric CO2 concentrations.'

Just started catching up on reading the blog comments ...

Okay ... question for you:

It's been shown that specific wave lengths are correlated with plant growth/maturation. This is a key reason why vertical ag production has increased productivity (and profitability) - they're using purpose-made lighting. I'm wondering how the axial tilt cycle (approx. 42,000 years) alters the type and amount of various sun wavelengths on our globe therefore how the axial tilt cycle might impact less mobile (pre-historic) civilizations. For example: regions that for generations had long summers (current US Farm Belt region) could rely on two crops vs. one crop per summer (Canadian Prairies) therefore could sustain larger populations ... larger populations usually mean more access to labor to build infrastructure, more skill diversity, etc.

BTW - We're at the midpoint of the max axial tilt.

Chinese also had natural gas pipelines made of bamboo, used to pipe gas to fuel evaporators at the saltworks.

traces left behind -- please search this page for 'dead zone'... not just wood rotted or iron rusted, there'll be patches where toxic runoff accumulated in low lands and nothing would grow there... arsenic soaked wood leaches out and eventually the wood chemically (but not biologically) degrades... the cellulose further degrades but arsenic being a chemical element just sit there waiting for random opportunities to link into various compound

covid fun fact -- what sneaks up on you is slow loss of spelling and longer time to retrieve words... last couple days it stealthily did that to me and I needed more than ten minutes to recall 'mutiny' last week and 'reign vs rein' was an ankle tripping moment whilst working on my novel... appears to be getting better today

• What about truffles? The huge part underground? Or some trees, that communicate through roots?*

Actually, the mycelia of many truffles only grow a few centimeters from roots. There are huge numbers of complexities I’m avoiding to keep this civil, but the big thing is that most ectomycorrhizal fungi get their carbs from their “sugar daddies”, the plant roots. Growing near those roots often makes a lot of sense for a bunch of reasons.

Okay ... question for you:…

Welll…the tropics get the most light, so all else equal, that’s where you’d expect the most people. Right? Then we’ve got the problems of the Sahara and those other subtropical deserts that have a lot of sunlight but not a lot of people. That need’s explaining too.

Then we’ve got the whole Industrial Revolution problem, in that it happened in the north temperate zone, and ended up with huge surpluses of people emigrating all over the world. Why did the Revolution start in England and not Borneo? They’re both islands with lots of fossil fuels, and Borneo has more sun and has been hosting hominids longer than England. Why didn’t the Industrial Revolution start in Borneo?

One answer is that it isn’t about photosynthesis. Basic vanilla photosynthesis hits a maximum energy capture rate at about 30% of full tropical sunlight, and the excess energy beyond that is typically diverted and wasted so as not to kill the leaf. You can do the trig to figure out what latitude corresponds to 30% of full sunlight. It might surprise you.

There are a bunch of other answers to the questions I posed above. I’ll leave those for others to ponder.

Question: Just how advanced could a purely stone age civilization get?

Maybe ask the Maya? You don’t need metal to feed millions of people and have a high civilization. You really only need it to defend against marauders who do have metal weapons.

H @ 258
It's about Disease, isn't it? Even 18thC Britain had a lower mortality/disease rate than Borneo et al, right?

Greg Tingey 260:

...aside from urban centers where crowding made disease transfer easy along with the cross-contamination between raw sewage and water sources

when considering industrialization, knowledge transfer is critical... between individuals and workshops and (eventually) corporations... not only the written word but the education to leverage books-diagrams-pick-lists

when the UK was getting started industrializing in 1780s to 1830s there could easily been technology transfer to Eastern Europe (Russia, Poland, etc)... if not for mass illiteracy being deliberate governmental policy

Paul McCauley has uplifted Racoons doing deep time archaeology in Beyond the Burn Line, excavating very ancient cities once occupied by the Ogres ( that's us) and picking through their trash. Raising the questions, who uplifted the Racoons, and the Bears, and are the Ogres really gone?

Re: '... longevity of a past civilization should be proportional to its ability to be environmentally sustainable, and so by definition less detectable.'

Agree! They'd be full-on 3-R'ing.

At the same time such a civilization might also have manipulated/bred various life forms for specific attributes. If so, then a map/timeline showing where and when the largest number of new species came into existence could help locate a past advanced civilization.

About sapient species: in no way an expert on this but my impression is that there's a strong connection between species intelligence and longevity. (The only exception I can think of is the octopus.) This intelligence-longevity relationship would be a natural basis of figuring out which species would be boss and which species would be servant/slave. (Yeah, I know: cats are our masters!)

Still catching up on comments but wondering ...

Large-scale neural networks - fungi (specifically mushrooms) apparently have vast underground neural networks. A possible SF scenario could be that we're seeing the protracted death by tissue/molecular fragmentation of some past ancient civilized species, i.e., ancient civilized mushrooms had much denser and tightly packed nervous systems distributed on an equally large area. There's data showing that COVID-19 can smoosh neurons together (thereby essentially destroying their function) so maybe some other virus can snip and thin neurons apart into what might still look like a neuron but without a key function such as connectivity/electrical impulse transmission. So death by dumbing down via a neuron-destroying virus* could also be on the table as a possible civilization extinction scenario.

*Some viruses can embed themselves in ova/sperm DNA therefore are heritable.

Its such an impressive structure that it draws people from across the globe - even officers of the KGB couldn't resist.

It might surprise you

Or it might not, although pushing things here risks treading in some sort of religious mess and best avoided. I think table 2.10 here is the interesting piece. It shows pretty clearly why our UK friends are skeptical about solar, and also why it's in their future anyway. The especially interesting areas are where the length of the day in summer overrides the angular reduction in insolation. But anyway, not trying to make a point or anything :)

Yes. I do get extremely bored by Californians incorrectly telling us (British) what crops we can grow and how effective (local) solar power is for us. Even that graph is misleading, because it does not allow for atmospheric absorption (which is a major factor in most high latitudes), but Weatherbase has a new. shiny, totally buggered Web site so I can't provide figures until I find a new source. The executive summary is that even southern Britain has only 3 months of peak growing season, the insolation drops off rapidly outside that, and outdoor crops need to be either cold and dark tolerant or be very short-season varieties. That is why we now grow almost entirely winter wheat, why maize (even for fodder) wasn't viable until a few decades ago, and why a lot of vegetables that grow well at cool conditions in 35 north won't grow here.

As we have discussed ad tedium and ad nauseam, importing solar electricity from north Africa makes sense in a way that covering our farmland with panels doesn't. It's the winter when we need it most, dammit!

No. Look at the west African empires - their technology was comparable to Europe's 800 years back, and their cities were as large. The spread of literacy by the Islamic world inteacted with them as it did with us. Why one took off and the other didn't, I don't know, but I suspect it's better described as chance than looking for an external cause.

structure with stone to its physical limits

The Great Pyramid is ~140m tall, but Everest is almost 9000m and Mauna Kea is over 10,000m (most is under water) so 140m is more the limit on human willingness to pile rocks... you need a pretty well organised civilisation to manage the project rather more than you need stronger rocks.

You seem to be saying periodic where you mean predictable. Firstly, if you look at those graphs, even the most regular are not perfectly periodic over ANY scale; they're more complex than that.

If you read the Wikipedia article, you will see it's very clear that these are cycles made up of the combinations of multiple periods. Some of these component periods are robust and long-lived; Laskar et al. (2004) argue that the 405-thousand-year period component of eccentricity variations is stable -- and potentially detectable in the geologic record -- up to 250 million years into the past (this has in fact been geologically verified from sedimentation records). And Laskar et al. (2011) show that combined eccentricity variations can be accurately predicted (or retrodicted back into the past) out to about 50 million years.

So maybe the real reason Crossrail was so delayed was the thing they dug into that nobody talks about and survives

Brains doesn’t talk about his encounter with CROSSRAIL SPIKE PLUTO but he’s collected far too many Tube maps and he’s spending a lot of time with model trains lately. He’s definitely up to something. * grin *

Also, this makes me think that pretty soon someone is going to be coming to the attention of the Laundry or its successor. Consider a sample argument from an energetic kook rail fan:

Now that the Big Secret is out and ordinary folks know about magic, it can be used openly. The public has seen some things and knows of the Alfir, so they should be ready for dimensional portals. London needs portals! Just think how much better Northern Line would be if it ran as counter-rotating loops like the Circle line, and it only takes a few portals – imagine adding a short circular loop of track with High Barnet, Edgeware, Battersea, and Morden only a few hundred meters away from each other!

Some spoilsport would have to explain why this is a bad idea, and especially not something to do in a crowded city.

(Conjecture: Even adding teleportation portals would not make using Heathrow convenient.)

I am amused by the thought of Londoners who do not really believe that other planets exist until it’s possible to get there by Tube.

Re Neanderthal extinction:

My understanding is that there isn't much of a consensus on the cause(s), and what consensus there might be is more around demographic factors (the historically small sizes of Neanderthal populations making them vulnerable to things like inbreeding and the Allee effect). This survey of about 200 anthropological/archeological researchers who work on Neanderthals suggested that demographic explanations ranked highest, followed by climatic ones.

Printing presses, gone? I strongly disagree... given that type is LEAD.

Printing presses are useless without paper. And have you ever tried making paper? It's kind of difficult without a fine metal mesh screen, and a suitable source of fibres. Rag paper is best, but you need the woven fabric that the rags ultimately come from, and textiles are hard (labour-intensive as hell until you've got the spinning wheel or, better still, spinning jenny -- the latter of which pretty much requires metalworking). Paper made direct from plant fibers is a maybe (indeed, wood pulp revolutionized newspaper publishing in the 19th/early 20th century) but producing enough pulp was itself an industrial process that I'm pretty sure requires more than stone axes.

Saying "movable type!" is like looking at a Panasonic home breadmaker and thinking "bread is easy!" without any conception that there might be a requirement for harvesting edible grass seeds and milling them into flour first, never mind developing and maintaining a starter culture and learning to do all the mixing/kneading/proving/baking work by hand.

Q: okay to discuss failure modes?

yet again the USA is leading the way in all manner of retro and repulsive policies... child labor!?

https://www.theguardian.com/commentisfree/2023/sep/27/us-legislators-child-labor-corporate-profits

this is yet another battle fought and won decades ago... and here we go again having to teach fools 'n fascists to treat children as humans in need of education rather than cheap laborers with small hands

so... what does it say of a species long term survivability if it regards its own offspring as expendable?

That’s both correct and misleading. There is decent evidence that some Neanderthals did survive the volcano, in a small, inbred population in Spain.

That does not mean that the primary reason their population crashed was inbreeding.

There are a couple of things to realize here. One is that there are two classes of explanations for Neanderthal extinction. One class is based on selection: they died out because they were inferior in some way. The other is neutral, that they were equivalent to modern humans and died out due to chance or bad luck. The supervolcano idea is a type of neutral hypothesis.

Now, there are people, like me, who believe that it’s useful have a neutral hypothesis to disprove as part of demonstrating that a selective hypothesis better fits the evidence. So if you believe that, say, only inbreeding doomed the Neanderthals, then you have to explain why they seem to have disappeared only after the eruption. You also have to explain why most of us have some Neanderthal genes, if they only had kids with kin.

Thing is, I’m not a paleoanthropologist, but I do know what their major job is: it’s not to be right, it’s to keep their labs funded and make payroll every month. If they wanted to study volcanoes, they’d be vulcanologists. So of course they’re going to prefer arguments based on the idea that Neanderthals were different and worthy of study. And I can’t blame them, either. I dislike working on stuff outside my field too, and I’ve done a lot of it.

But it doesn’t mean those of us who aren’t in the field can’t talk about that big volcano. Especially since the Romans used its ash to make their concrete.

Printing presses are useless without paper.

Well, it would mean a different use model than we have (no 50,000 runs for the morning and evening newspapers), but printing onto parchment/velum rather than having scribes with quill pens doing the job might be useful in some contexts. Maybe papyrus, birch bark etc.

Actually, I have made similar materials, more by accident than intent. Making suitable plant fibres doesn't need more than pounding stones, vaguely watertight containers and alkali or retting - the problem comes in making it into something uniform and smooth enough for writing or printing on, which is where the mesh somes in.

My guess is that you could make something usable with no more than felt (which is made similarly to paper!), a flat surface and a smooth roller. However, making a flat surface and smooth roller is NOT simple without fancy tools. And vaguely watertight containers are trivial, either.

https://www.instructables.com/How-to-make-paper-1/

https://www.pita.org.uk/what-we-do/news-services/609-make-paper-from-plants

The other side to that is that the volcano hypothesis is not really convincing, on its own. The ash went northeast, and the prevailing winds mean that western and northern Europe would have suffered no worse that east Asia or even north America. So how many species died out in those following that eruption?

The point here is that one bad year (and a 2-3 Celsius drop is not a really bad year) followed by a few poor ones very rarely wipes out healthy populations of long-lived animals than depend on other long-lived animals for food. I agree that they were never common, but that's not the same as being a weakened population (for whatever reason). It's not as if they hadn't survived a good many climate challenges before.

A Subway Named Mobius anyone?

Another fun issue is why a bunch of civilizations started popping up independently around 5,000-6,000 years ago. People started building pyramids by rivers in Egypt and Peru within a few centuries of each other, even though they last shared an ancestor at least 15,000 years before that.

A global amelioration of climate is a really good explanation for why civilizations started popping up on fertile lands near rivers in the Fertile Crescent, China, coastal Peru, and likely along the Mekong, Indus, and other areas that haven’t been surveyed as well yet.

That’s the kind of thing you’d expect from the Milankovitch Cycles. The primary civilizations didn’t arise in lock step, of course, but people who’d been living in widely separated areas all started doing things very differently than they had in the past around the same time. That argues for either global communications, or removal of a global climate constraint. Since there’s no good evidence for global communication in the Neolithic (ancient aliens?), but there is decent evidence for a more stable climate, the latter is a better explanation.

Brian Fagan’s book The Long Summer: how climate changed civilization goes into stuff like this.

No. Look at the west African empires - their technology was comparable to Europe's 800 years back, and their cities were as large. The spread of literacy by the Islamic world inteacted with them as it did with us. Why one took off and the other didn't, I don't know, but I suspect it's better described as chance than looking for an external cause.

Well, I’d say neither. I was subtly pointing to the problem of multiple constraints. The Sahara is a bit short of water to grow forests, even though it has enough sunlight. And plants as a group have all sorts of tricks to grow in suboptimal conditions, which is one reason there are so many different species. And plant growth itself is a nasty metric. You can grow corn in England, in the sense that the plant will grow. But I’ll bet you don’t get much grain off it? Where something can grow and where it can feed a civilization are two different questions.

That said, I do agree that chance plays a big part. That’s been a theme in ecology for the last few decades, telling the difference between patterns arising due to chance and patterns arising due to particular factors, such as environment, predation, and so forth.

There are a couple of things to realize here. One is that there are two classes of explanations for Neanderthal extinction. One class is based on selection: they died out because they were inferior in some way. The other is neutral, that they were equivalent to modern humans and died out due to chance or bad luck. The supervolcano idea is a type of neutral hypothesis.

If you had read the survey I linked to, you'd discover that there are three main classes of explanation: Neanderthals died out due to selection effects (e.g., outcompeted for resources by modern humans); environmental causes (e.g., a volcano); and small-population demographics. (It's not clear what you mean by "neutral hypothesis", but it doesn't seem to be doing anything useful here.)

On the offhand chance you were trying to invoke the idea of null hypothesis, I'll point out that massive volcanic eruptions are dramatic and rare events, pretty much the opposite of a null hypothesis.

you have to explain why they seem to have disappeared only after the eruption.

If you believe in pure "post hoc, ergo propter hoc" reasoning, sure. Otherwise, you actually have to work out how close in time the extinction was to the eruption, and how likely or unlikely the null hypothesis of demographic extinction would be in that time span.

You also have to explain why most of us have some Neanderthal genes, if they only had kids with kin.

No, because it's a statistical argument: there was simply too much inbreeding, not the straw-man argument that all Neanderthals only ever engaged in inbreeding.

Thing is, I’m not a paleoanthropologist, but I do know what their major job is: it’s not to be right, it’s to keep their labs funded and make payroll every month. If they wanted to study volcanoes, they’d be vulcanologists.

Ah, it's the "scientists are all corrupt, so we can ignore what they say" argument. Wonderful. (You do realize you're deploying the same sort of argument climate-change denialists like to use, yes?)

(The irony is that the majority of the authors of the Golovanova et al. (2010) study that you've apparently decided is The Truth, including the lead author, are paleoanthropologists -- exactly the sort of people who, according to you, hate and ignore volcanoes.)

The fact that paleoanthropologists -- however much you may distrust them -- haven't all decided volcanism was THE cause could be because there have been some counterarguments in the scientific literature since the Golovanova et al. study. For example:

Lowe et al. (2012): "Our results confirm that the combined effects of a major volcanic eruption and severe climatic cooling failed to have lasting impacts on Neanderthals or early modern humans in Europe. We infer that modern humans proved a greater competitive threat to indigenous populations than natural disasters."

and

Black et al. (2015): "We find that peak cooling and acid deposition lasted one to two years and that the most intense cooling sidestepped hominin population centers in Western Europe. We conclude that the environmental effects of the Campanian Ignimbrite eruption alone were insufficient to explain the ultimate demise of Neanderthals in Europe." (I'm afraid both the lead and last authors of this paper are actual volcanologists.)

A reduced population that was, more or less, interfertile with us, might easily have been diluted beyond recognizability. We are the end result of a wide variety of beings who found each other arousing.

The empires were not in the Sahara, but the jungle (e,g, Benin) and Sahel (e.g. Mali).

An equally possible explanation for the development of simultaneous, independent civilisations is a combination of chance and that it takes a certain amount time to happen. If you take a sample of three from any of the common continuous distributions, don't be surprised if the points are very close together. There is at best feeble evidence from that occurrence that there was an external cause.

when the UK was getting started industrializing in 1780s to 1830s there could easily been technology transfer to Eastern Europe (Russia, Poland, etc)... if not for mass illiteracy being deliberate governmental policy

Scotland had mass literacy during that period (but was emerging from a couple of centuries of presbyterian theocracy). England ... mass illiteracy wasn't official policy but was substantially the outcome of official policy: it wasn't until industrialization was well under way that the need for a workforce who could do sums and read instructions brought the need for primary education into national-level focus.

Poland was invaded and occupied during that period, mostly by Russia (and Prussia and Austria-Hungary). And Russia still ran on serfs who were pretty much slaves by any other name. Hence illiteracy as official policy.

Tallest stone structure? Sorry, all of you lose. The tallest freestanding stone (ok, masonry - brick, marble, and limestone) structure... is Philadelphia, PA, USA, City Hall, at 548' (167+m).

We seem to be talking past each other. I've seen a number of articles with them being connected to a huge node (or whatever it's properly called. "It is estimated that the mushroom hyphae can be as long as 1 km in the forest soil"

That wasn't what I was saying. Someone mentioned not finding printing presses, and I was replying that the movable type would be around a looooong time.

Neanderthal die-off. Are there any indications in the latest bones of either disease or starvation?

No! I mentioned not finding printing press output. Didn't say anything about the presses themselves.

"It's not clear what you mean by "neutral hypothesis""

He means one that doesn't risk getting into palaeoracism, or providing material that can be twisted to support modern racism.

ust think how much better Northern Line would be if it ran as counter-rotating loops like the Circle line, and it only takes a few portals

I'm way ahead of you in the planning stage, but it's about the third project down in the universe -- first up is The Last Laundry Novel, then New Management #4; I thought this was going to be a sub-plot of #4 (New Management vs. commercial uses for the Dream Roads: what could possibly go wrong?) but I now think it warrants a whole book of its own. (Hint: deregulation of real estate development meets dream roads meets extraterritorial jurisdiction and suburban sprawl goes inter-universal ... at least until the hazards of commuting start to include things eating your brain en route to the office.)

Greg Tingey @ 253:

DP
"how high you can build a complicated structure with stone to its physical limits?"
Salisbury Cthaedral's spire is 123 meters tall ....

There's the other part though ...

"IIRC, the tallest non-steel, purely granite, "Skyscraper" ever built was a six story stone office building in Chicago. "

How many working floors are there inside that spire? Or inside the spire at Notre Dame

PS: IF I understand, Notre Dame's spire was a 19th Century addition or replacement for the original - but it looks like they ARE going to be able to recreate it. 🙂 That's a bit of happy news amongst all the other turmoil in the world today.

PPS: Didn't the Roman Republic have tenements 3-4 stories tall?

ISTR from a visit to the Gutenberg museum that the original black-letter bible took 4-5 years to print either 158 or 180 (reports differ) copies. Printed on linen paper 4-up, 322 pages per bible (two volumes per bible), containing "the Latin version of the Hebrew Old Testament and the Greek New Testament."

Prior to Gutenberg's process bibles would be copied by hand by a scribe. I don't know exactly how long this would take but I do know that a modern Torah scroll is likewise hand-copied by a scribe and takes roughly six months, and consists of the five books of the pentateuch (so ... maybe half a Vulgate bible? A third?).

Anyway, let's approximate hand-copying a bible to a year's work. And we know that the original Gutenberg bibles sold for roughly 100 florins, or three years wages for a clerk. Cheaper than a manuscript bible, but not hugely so. Most likely the benefit of having a printed bible lay in textual inerrancy, without any risk of copying errors (as long as it had been properly proofread).

Anyway, my point is that early printing was in no way a drop-in replacement for hand-copied manuscripts and on its own it wasn't going to revolutionize the dissemination of information. That would have to wait for cheaper paper (which the printing press created a need for).

movable type would be around a looooong time

Our type of type, lead, tin, antimony etc., perhaps.

But there are other types of type that have been used, e.g. wood, that might be harder to find across the megayears:

https://en.wikipedia.org/wiki/Wood_type

PPS: Didn't the Roman Republic have tenements 3-4 stories tall?

I live in a tenement dating to the 1820s, on the fourth or fifth floor (depending how you count -- it's on a hillside, there are basement levels on one side that are above ground on the other). Construction materials are stone (load-bearing walls) and timber (floor supports/joists).

Elsewhere in Edinburgh there are 16th/17th tenements as much as 10 stories high, built inside the city walls back when every 20-30 years the English fleet would sail into Leith and torch everything that wasn't sheltered.

The construction methods would probably have been familiar to the Roman Republic (slates instead of clay tiles for the roofs, but otherwise similar) ...

Howard NYC @ 256:

covid fun fact -- what sneaks up on you is slow loss of spelling and longer time to retrieve words... last couple days it stealthily did that to me and I needed more than ten minutes to recall 'mutiny' last week and 'reign vs rein' was an ankle tripping moment whilst working on my novel... appears to be getting better today

Hope you get a lot better SOON. I've been lucky so far. I've also been sort of semi-careful ... getting my shots & trying to always keep a mask handy (& use it) when I go out.

I'm already a sub-Genius. If covid makes you stupid and I slide any farther down that slippery slope, I'm gonna' die! 😟

A global amelioration of climate is a really good explanation for why civilizations started popping up on fertile lands near rivers in the Fertile Crescent, China, coastal Peru, and likely along the Mekong, Indus, and other areas that haven’t been surveyed as well yet.

I might be inclined to wonder a bit about the long, slow process of technological development, in the sense that human technology ca. 10,000 years ago was more advanced than human technology 50,000 or 100,000 years ago, and thus perhaps more conducive to developing agriculture.

But otherwise, yes, climate seems like a plausible explanation.

Brian Fagan’s book The Long Summer: how climate changed civilization goes into stuff like this.

Looks interesting; thanks for the recommendation!

peteratjet @ 262:

Paul McCauley has uplifted Racoons doing deep time archaeology in Beyond the Burn Line, excavating very ancient cities once occupied by the Ogres ( that's us) and picking through their trash. Raising the questions, who uplifted the Racoons, and the Bears, and are the Ogres really gone?

First time reading that I only got as far as "Paul McCartney has uplifted racoons ..."

That's what I thought I saw....

Sorry, misread you.

Most likely the benefit of having a printed bible lay in textual inerrancy, without any risk of copying errors (as long as it had been properly proofread).

Perhaps getting a bit off topic (we're not at 300 yet, are we?), but one thing that Bart Ehrman's expositions on New Testament textual criticism emphasizes is that, pre-printing-press, just about every hand-copied copy of a text differed from the version being copied in numerous places. Most of the time those were minor differences, but sometimes sometimes they did matter for the sense of the text.

Kinda like DNA replication, now that I think of it.

Anyway, let's approximate hand-copying a bible to a year's work. And we know that the original Gutenberg bibles sold for roughly 100 florins, or three years wages for a clerk. Cheaper than a manuscript bible, but not hugely so. Most likely the benefit of having a printed bible lay in textual inerrancy, without any risk of copying errors (as long as it had been properly proofread).

Seeing as the first books printed by Feng Dao were Confucian standard texts and commentary - texts used for the Imperial Examinations - inerrancy might be a regular reason to prefer printing over copying early in the development of the technology.

I'd love to find direct comparisons between the economics of early European and Chinese printing, since Chinese paper use was so much further developed (they were producing special-purpose toilet paper at a massive industrial scale by Gutenberg's time).

Didn't the Roman Republic have tenements 3-4 stories tall?

Up to 9 stories in pre-imperial times. Assorted Emperors set planning regulations that reduced the maximum allowed height but 6 or 7 floors were common. Penthouses were for the lowest of the plebs and non-citizens, ground floor for shops and businesses with the best apartments on the first floor.

Charlie Stross @ 295:

PPS: Didn't the Roman Republic have tenements 3-4 stories tall?

I live in a tenement dating to the 1820s, on the fourth or fifth floor (depending how you count -- it's on a hillside, there are basement levels on one side that are above ground on the other). Construction materials are stone (load-bearing walls) and timber (floor supports/joists).

Elsewhere in Edinburgh there are 16th/17th tenements as much as 10 stories high, built inside the city walls back when every 20-30 years the English fleet would sail into Leith and torch everything that wasn't sheltered.

The construction methods would probably have been familiar to the Roman Republic (slates instead of clay tiles for the roofs, but otherwise similar) ...

That's kind of what I was getting at, that there are multi-story buildings predating the iron (or steel) framed skyscrapers with usable space on their upper floors; as opposed to Greg's 123m Spire on Salisbury Cathedral.

IIRC, DP referred to a building in Chicago; the Monadnok Building is the tallest [215 feet (66 m)] purely masonry BUILDING at 16 stories.

PS: To your earlier "And have you ever tried making paper?" ... Yes, I have, using silk fabric stretched on a wooden frame for the screen, dryer lint for the rag content & shredded junk mail for the fiber. Didn't turn out great, but I have some appreciation for the effort involved. 🙃

No, I don’t think paleoanthropologists are corrupt, any more than any scientist is. I do, however, think that funding flows to controversies, and so long as nobody seems to be milking it too assiduously, why not keep the debate going and use it as a reason to fund more studies? You’re also right that the evidence sucks for all three of your classes of hypotheses, so calling for more science isn’t corrupt in this case.

I’m sympathetic, because the funding rate for grants is abysmal. Anything researchers can do to improve their chance of getting funded is to the good, at least from the researcher’s perspective.

As for neutral theories, they’re a thing in ecology. The basic idea is that whatever caused the pattern of organisms you’re studying has nothing to do with the traits of the organisms you’re studying. The classic example is the distribution of tropical rain forest trees. The original neutral theory simply proposed that the distribution was more or less random, and it explained the distribution of plants surprisingly well.

For the supervolcano theory to be neutral, you’d have to show that every hominid, regardless of species, was wiped out in the area devastated by the volcano, and it just so happened that the majority of Neanderthals were in that area. Their extinction would be neutral with respect to their biology. And there’s some evidence this happened.

You can of course use the supervolcano theory as a null hypothesis against which to test non-neutral biological hypotheses that modern are more fit than Neanderthals. The general problem is that humans and Neanderthals certainly hybridized and shared the same territiry, for some value if share, for millennia prior to the eruotion, so there’s not a big difference between these hominids regardless.

_ the sort of people who, according to you, hate and ignore volcanoes._

That's where you've lost everyone who might have been following up to that point, I think. As a statement it's both obviously false and a demonstration that you've misjudged H's position: the rest of your comment can be re-read as merely re-interpreting the facts to support this misjudgement.

There are other issues, and while I don't want to pile on it's worth talking to some. Separating inbreeding into a third "class" is a category error: I think what you've actually done is identify that it's an effect, either of endogenous factors (poor adaptation) or exogenous ones (environment) and not a cause in itself.

I think the overall suggestion that Neanderthal extinction is overdetermined is not something I can entirely go along with: there are multiple causes which apparently are not independently sufficient. So what we're looking for is the "but for" legal test (see the wikipedia entry for Proximate Cause). The overall question is whether Neanderthals might have survived "but for" the volcanic event, and since the event occurred, it's tough to argue in terms of a counter-factual. That doesn't mean it isn't a worthwhile discussion to have, particularly for the reasons H has discussed (and Pigeon spelled out).

We live with a modern technocratic western perspective that thinks meritocracy is a fact of nature and therefore generalised inequality is fundamentally just (and before someone takes offence, I'm not saying this is what you believe, I'm saying this is a preferential bias we receive from our cultural heritage which we have our own individual opportunities to grapple with, but it's definitely there as part of the background and sometimes people even treat it as a null hypothesis) and it's always worth pointing out that a contrary view is available and has been at least since Ecclesiastes 9:11 (for example).

"Another reality of rural life is that you spend a lot of time in your car, so that talk radio becomes a habit for many people."

And because it's in the car, it's not that easily checked, even if the listener felt like doing it.

Long COVID - summary of findings

Really good YT video of a presentation at the NIH summarizing findings to-date re: long COVID. There's also a time-stamped 'transcript' that you can read along with.

'SARS-CoV-2 reservoir: potential a driver of inflammation and other disease mechanisms in Long COVID' (Length: 21:01)

https://www.youtube.com/watch?v=XC-57ctnN38

For me the key take-away is: COVID reservoir is in tissues, not blood.

Whitroth -

I'd like to say 'hope you're feeling better soon' but the more realistic hope/advice is: be patient with yourself and take as long as you need to to recover. This is a long haul process. Also a good time to ramp up the nutritional value of your diet: your body needs the best quality ingredients/building blocks to replace damaged cells/tissues.

It’ll be interesting to see how this compares with Tim Powers Vickery and Castine series. He’s using the moving cars on the LA freeway system as a magic generator. It is an interesting conceit.

=+=+=+=

Kardashev 301:

amongst scholars studying various editions of Koran, there's lingering argument about miscopying which changed '72 weight-units of fruit' into '72 virgin girls' which were promised to each jihadist upon arriving at Paradise

which leads to the concern of what was miscopied in other religious tomes... and in turn offers room for horrific comedic opportunities to play out in Luandryverse

co-mingle typographical errors in e-book version of Kama Sutra with magic ley lines under apartment buildings and jaded boredom of long married couples...

there's a wave of folks in their fifties dying (very) happy after twenty-plus days of exploring one new page a day until they either starve to death or simply try something too demanding of mere mortal flesh... you ought pity the coroner and/or paramedic who have to, by law, administer aid and/or confirm cause of death...

with the very human temptation to steal that magicked version of Kama Sutra by one or another first responders... thereby continuing the spread of going out with a bang and leaving behind two or more grinning corpses in one bed

(crisis needs a pithy label of exactly three words of level-five snarkiness)

also cults reviving Roman orgies catered by Doordash and 'specialty leather equipage' same day delivery via Amazon Prime ("your orgasm guaranteed in thirty minutes or the bewitched riding crop is free")

=+=+=+=

yes, the long-ish-covid induced 'brain fog' is dissolving and now looking back it was mild these last three weeks, (as in, me being mildly drunk and clumsy sans booze, ugh)

no, it will not be the last such 'brain fog'... only reason I am not utterly wrecked is 3X vax... let others proclaim their genetic superiority by refusing vax... thus far 300,000+ conservatives have died for their beliefs in 'freedom' and mocking science... yup... us liberals and fact-nerds and wimp-taking-vax are so utterly 'owned'

=+=+=+=

Trump -- last week he promised action against MSNBC/NBC for “country-threatening treason”; this week his real estate 'empire' is verging on being disassembled; $400+ million in debt comes due in 2024, Trump lacks resources to pay it back; jerry-rigged and over-leveraged and falsehoods all coming out in the open leaving banks (and their regulators) with potential of a mini-me version of a real estate collapse which will be rather embarrassing to GOP politicians and banking executives; hence the threats to journalists; I'm ready for observing the coming shitstorm, having stockpiled five pounds of popcorn kernels;

“... In finance, once the dominoes start falling, it becomes basically impossible to save it. ... Trump is monumentally, stupidly greedy in that he isn’t actually paying for a number of key lieutenants in terms of their legal needs, and they’re facing financial collapse of their own ..." -- William Black, white-collar criminologist

=+=+=+=

I might be inclined to wonder a bit about the long, slow process of technological development, in the sense that human technology ca. 10,000 years ago was more advanced than human technology 50,000 or 100,000 years ago, and thus perhaps more conducive to developing agriculture.

A lot of people have a tendency to underestimate the knowledge/skill/infrastructure that goes into early technology, including biotechnology like breeding plants and animals. Especially when all that knowledge has to be committed to memory.

Trump is monumentally, stupidly greedy

Dragging this back on-topic, is it possible Trump has been casting a glamour all these years, and his apparent dementia is actually K-syndrome?

argument about miscopying which changed '72 weight-units of fruit' into '72 virgin girls'

Either way it's more dates than any of them had in real life...

I'm also bemused that that's seen as a good thing. The Koran is explicit (as is the Bible and likely the Torah) that having assorted wives, concubines and slaves is fine, but you have to support them. All 72 of them!

Oh come on. Everybody knows that when it comes to the extinction of the dinosaurs and the Neanderthals, it’s The Lone Gunman hypothesis that makes most sense.

• Dragging this back on-topic, is it possible Trump has been casting a glamour all these years, and his apparent dementia is actually K-syndrome*

Dementia, the legal refuge of scoundrels? Too bad there’s no mental competency requirement for US President.

Apropos of a deep future setting…

It occurs to me that Pangea Ultima, the future supercontinent some 200-250 million years in the future, would be the time when whatever carbon we biologically sequester now will be good quality coal and oil.

Humanity might survive that long by adapting quickly through technology and culture to changing environments, rather than slowly through biological evolution.

The sun will be considerably brighter, so humans of that deep future will either be shiny or really melanistic, and I’m betting the latter.

Now, couple this distant future with the notion of a New Carboniferous in our near future, where biohackers create decay- and termite-resistant wood to both make better building materials and better carbon sequestration material.

The indigestible wood of the New Carboniferous becomes the coal that powers a steampunky Industrial Revolution 240 million years later in Pangea Ultima.

Combine these two scenarios, with the new industrialists studying the remnants off us precursors in their coal beds, not realizing that they’re following in our path. Call this the Pangea Ultima/New Carboniferous scenario, or PU/NC.

Have fun with it.

...deregulation of real estate development meets dream roads meets extraterritorial jurisdiction and suburban sprawl goes inter-universal ... at least until the hazards of commuting start to include things eating your brain en route to the office.

This only amplifies the already existing status enhancement of having a home near the center of London. Ludicrously high real estate prices mean only those blessed by Mammon can reside near the City.

That the peons and apostates who are not beloved of Mammon lose themselves by commuting through the bowels of Hell only shows that executives are better because they are wealthier.

(Should I avoid speculating on this too much so as not to distract from your own plotting? I'm sure there'd be a demand for trains that ran between London and Glasgow in 20 minutes, but we don't have to hash that out here.)

timrowledge 314:

Yup... Lee Harvey Oswald did 'em all... rather than as others insist it was not Colonel Mustard in the Library with the Candlestick but... Lee Harvey Oswald in the Time Machine with the Rifle

The indigestible wood of the New Carboniferous

Are you thinking of the "recycled" plastic fence posts and garden furniture that's being made now? I am.

(it's downcycled - you take any old plastic waste, heat it up and compress it. Avid breathing the resulting fumes and do be sensible with the liquids that come out)

uhm... "Avid breathing"...?

*Pangea Ultima, the future supercontinent some 200-250 million years in the future, would be the time when whatever carbon we biologically sequester now will be good quality coal and oil.

Humanity might survive that long by adapting quickly through technology and culture to changing environments, rather than slowly through biological evolution.

The sun will be considerably brighter, so humans of that deep future will either be shiny or really melanistic, and I’m betting the latter.*

Problems I can see:

The end result is a "cool Venus", where the surface liquefies every few tens to hundreds of millions of years to release trapped heat (either via giant igneous province eruptions or lots of small local volcanoes).

This is, I submit, not a portrait of a life-hospitable planet.

Now, the full "no more plate tectonics/cool Venus" scenario takes more than 250M years to emerge -- probably a lot longer. But Pangaea Ultima is going to make things worse because it's going to have a huge, arid desert interior with much-reduced weathering of rocks (no rain) hence less release of bound minerals into the biosphere. Look to Australia's interior and the Nularbor Plain, then square it.

Also just to note that in mammalian terms, 250 million years separates us from the End Permian and the extinction of most synapsids and their replacement by sauropsids. (We're descended from the small surviving synapsides, just as birds from the small surviving sauropsids that made it past the end-Cretaceous event). The dinosaurs fitted entirely in that 250 million year gap.

I find it almost inconceivable that hominids as we know them will survive in this world 250 million years hence; even expecting mammals to be around is a bit of a reach (likely something else will replace us due to some as-yet-unforeseen mass extinction event).

Today's Guardian long read is on bacterial plastic eaters.

That's where you've lost everyone who might have been following up to that point, I think. As a statement it's both obviously false and a demonstration that you've misjudged H's position

It's true that my "hate and ignore volcanoes" was exaggerating for effect. But it's difficult to interpret something like heteromeles' statement -- "If they wanted to study volcanoes, they’d be vulcanologists. So of course they’re going to prefer arguments based on the idea that Neanderthals were different and worthy of study. And I can’t blame them, either. I dislike working on stuff outside my field too, and I’ve done a lot of it." -- as something other than "paleoanthropologists dislike dealing with volcanoes". (It's a rather simplistic and narrow-minded assessment of what scientists might or might not be interested in, in my opinion.)

Separating inbreeding into a third "class" is a category error: I think what you've actually done is identify that it's an effect, either of endogenous factors (poor adaptation) or exogenous ones (environment) and not a cause in itself.

If it's a "category error", then it's a category error on the part of paleoanthropologists, not me; I was simply reporting how they were describing things. Here's an explanatory excerpt from the survey paper of Vaesen et al. (2021) [note that this is an open-access paper, so you can read it yourself if you're interested]:

Numerous hypotheses have been advanced to explain the disappearance of Neanderthals. According to a first category of hypotheses, the event was causally related to the migration of modern humans into territories occupied by Neanderthals: resident bands of Neanderthals and incoming bands of modern humans found themselves in competition for the same limited resources. A competitive advantage for modern humans then resulted in the replacement of Neanderthals by the principle of competitive exclusion. This category of hypotheses comprises several variants, distinguishable by the type of competitive advantage they postulate....

A second category pertains to hypotheses that refer to the internal, demographic dynamics of Neanderthal populations. Even in the absence of competition with modern humans, Neanderthal populations might, generally, have been too small to persist in the long run. More specifically, their small size and limited interconnectedness would have made them highly susceptible to inbreeding (viz., reduction in fitness of individuals that arise from matings between genetic relatives), Allee effects (reduction in population growth rates due to problems in mate-finding), and stochastic fluctuations (sudden drops in population size due to random fluctuations in births, deaths and sex ratio)...

A final, third, category attributes the demise of Neanderthals to environmental factors. These factors include general climatic instability, extreme climatic conditions due to volcanic activity, the introduction of pathogens by modern humans into the immunologically naïve Neanderthal population...

Also, it's reductive (if understandable) to refer to demographic effects as just "inbreeding" (understandable in that it's a familiar and easily understandable concept). Vaesen et al. refer to "internal, demographic dynamics" as "inbreeding..., Allee effets ..., and stochastic fluctuations".

I had a dim memory of James Burke making the point that an early adopter of the printing press was the Church, mass producing papal indulgence forms ...

https://pages.mtu.edu/~rlstrick/rsvtxt/burke4.htm

Avoid breathing. Sorry the typo made it impossible to understand. Post-covid my spelling is not so good.

uhm... "Avid breathing"...?

The greenie version of sniffing glue: getting high while recycling plastic… :-)

Buggre All This for a Larke...

Do the actual buildings currently standing date back that far?

I was under the impression that most of actual buildings in the Old Town were Victorian replacements of earlier buildings but on the same road layout and footprint.

Yes the buildings really do date back that far in chunks of the Old Town. (Yes, there are Victorian inclusions, especially on the Royal Mile, which is a tourist hell, but if you hit the Cowgate you can go drinking in a 400 year old pub or three ...)

I seem to recall that one of Jill Connor Browns "Sweet Potato Queen" cook books had a possibly relevant recipe, the "Revirginator", haven't seen it myself, unknown how it might differ from the "Pan Galactic Gargle Blaster".

Sorry for not doing a more complete response, but I’m on an iPad, screen typing…

No coal: the point of the New Carboniferous is to make coal, and the mechanism is biohackers making rot resistant wood. This last is obviously a handwave, but if someone were to do it, it might involve something like biohacking an enzyme system that tacks chlorine onto some of the carbohydrates laid down in plant cell walls. Wood degradation only really took off in the Jurassic, if I remember correctly, so it might take tens of millions of years for bugs and fungi to evolve the ability to break the stuff down.

So yes, lots of coal production, high oxygen levels, big fires, plastic jungles, and ice ages. That’s the New Carboniferous, possibly for tens of millions of years.

Plate tectonics, etc. It’s currently thought that this starts seriously breaking down 500 million to a billion years from now. 240 million is reasonably safe. Days are currently getting longer at 1.78 milliseconds per century, so that’s unlikely to be a problem.

It’s also worth considering that the Siberian Traps caused the end Permian extinction in part because the volcanos almost certainly burned through a lot of Carboniferous coal. So if Large Igneous Provinces become a thing of the past, so do the extinction events they often cause.

As for hominids surviving…I didn’t say as we know them, but who knows, maybe we’re the mammalian equivalent of spiders and scorpions. Or moss.

More to the point, SFF accepts Vance’s Dying Earth series into the canon without comment. It’s okay to have really, really white men surviving until the sun goes out like a candle. Point out that the sun is actually getting brighter, so the people in a more realistic Dying Earth will be really black, and the word inconceivable is likely to show up. In the resulting conversation. This isn’t picking on you, but on everyone. Why does this happen?

the mechanism is biohackers making rot resistant wood. This last is obviously a handwave, but if someone were to do it, it might involve something like biohacking an enzyme system that tacks chlorine onto some of the carbohydrates laid down in plant cell walls.

Which is plausibly desirable if we want a carbon-negative construction material in the not-too-distant future (trees that provide timber that won't rot unless treated with some sort of artificial catalyst). Fast forward a few thousand years and hominins are no longer building stuff out of wood and horizontal gene transfer happens or the plantation trees escape and go native ...

(My bad for not spotting this earlier.)

One side-effect of chlorinated coal will be dioxin releases when we burn it. Yummy. (Not.)

Dying Earth futures: yup, the future of hominids is dark-skinned (especially if we figure out how to improve the efficiency of mammalian photosynthesis of vitamin D for those living at northerly latitudes).

You're responding to the wrong person - no COVID here (actually, just this morning, Ellen and I got our latest boosters, with added epsilon goodness).

We are, of course, hoping to be awake tomorrow, as Capclave starts, and we're planning on the GoH lunch, and I have a panel at 16:00....

H
As for hominids surviving ...
Last & First Men - Olaf Stapeldon, 1930.
Got to Eighteenth ( & last ) iteration of "humanity" on, IIRC _ Neptune.

Heh, heh. And in my future universe. loooong before 250M years, humans have become groupded space-dwelling beings

With respect to dinosaur high-tech civilization, I say that the existence of the Great Lakes banded iron formations disproves it. That those were still around to be mined out by us is strong evidence that we're the first to have been using iron metallurgy at scale.

Re: rot resistant wood for New Carboniferous Coal Swamps.

Mangroves.

Note that this is a category, not a species, and as a group they vary between 6 meters (US) and 65 m(Gabon) tall. Mangrove wood is known for being very decay resistant and tough. Normally it’s used in poles, but I think some is used for construction.

We also need mangrove forests to make coasts more resilient to cyclones. So my what if is biohackers figuring out how to create plantation mangroves on vulnerable coasts, and grow them taller and faster. As the terrible example of reed canary grass shows, it’s quite possible for a wetland plant bred to be fast growing and resistant to turn into a superweed. Good for armoring the coasts with incipient coal swamps. Maybe bad for any species that is mangrove intolerant?

In the longer term, there’s a phenomenon called adaptive radiation. It’s when one species invades a new habitat, finds a bunch of empty niches, and spreads rapidly into a flock of closely related, ecologically diverging species. The African Lake cichlids are thought to kick out a new species every 20 years or so this way. Not every clade radiates, but it’s plausible that some of the superweeds of today would speciate rapidly into swarms of weirdness if they survived an extinction event. Think mustard giving rise to Brussels sprouts.

Note, biohackers might also create chlorinated plastic rubber trees or some such. They just need to give the plants enough supplemental chlorine as a fertilizer salt to meet the plants’ demands. Yes, seawater has chlorine in it. Why do you ask?

https://www.theguardian.com/environment/2023/sep/28/plastic-eating-bacteria-enzyme-recycling-waste

this bacteria was doing much more than that – it appeared to be breaking down plastic fully and processing it into basic nutrients. From our vantage point, hyperaware of the scale of plastic pollution, the potential of this discovery seems obvious. But back in 2001 – still three years before the term “microplastic” even came into use – it was “not considered a topic of great interest”, Oda said. The preliminary papers on the bacteria his team put together were never published.

Charlie Stross @ 330:

Yes the buildings really do date back that far in chunks of the Old Town. (Yes, there are Victorian inclusions, especially on the Royal Mile, which is a tourist hell, but if you hit the Cowgate you can go drinking in a 400 year old pub or three ...)

Since much of Edinburgh is a world heritage site, what will they do IF something like what happened to Notre Dame Cathedral happened there?

I hope this is not considered off-topic.

Flagler's Train: The Florida Keys Over-Sea Railroad [PBS YouTube]

I think the segment beginning at 27:45 is relevant to the discussion of reinforced concrete, but the whole thing may be relevant to the longer conversation about what could be discovered about previous civilizations from the structures they leave behind.

The railroad is gone, but the overseas highway replaced some of the right-of-way improvements and others are still in use today as heritage trails.

How long will remnants of these constructions be discoverable after we're gone?

Pangea Ultima:

29% land all locked together into a nightmarish extreme of here-n-now Australia but without any decent beer (oh! the horrors!)

71% seawater without much in way of annoying lumps of land for sea-based urbanization

without human intervention -- genetic splicing via handwaved uber-tech[1] or patient hand breeding -- there will still be evolution by sea veggies ("seaweed")... better at enduring extremes of cold polar waters as well equator... in addition plankton does much the same as kelp... adapt and spread... so for sure there will be fish...

by way of human intervention there will likely be floating villages (though not entire cities, let's not be too silly)... uber-kelp patches woven and grown together into hexagon "carpet pieces" then linked together...

each being about 1,785 meters in radius (10^7 meters of surface area)... each supporting population of approx 1,000 humans... housing surrounded by growing surface of 1.0 hectare per human providing 90% of daily calories along with select sea weeds/veggies... land-based veggies also tweaked such as potatoes providing more protein and various critical vitamins is plausible bit of handwaved uber-tech;

source of animal protein is (a) either dwarf cattle or tweaked rabbits, eating vegetation humans cannot (b) lots 'n lots of fish

so bad news no wheat-based beer...

...but good news lots of shrimp to solar barbeque

and yes there will be sails grown since there's a need for guided course correction to avoid drifting too polar or too equator as well need for trade opportunities...

such as those few industrial units producing rugidized electronics (iPhone mark 87 with 256Tb RAM), aluminium sheets for solar cooking/baking units, plastic bin storage for rainwater collection, solar photovoltaics, carbon-fiber cabling, plasticized paper books, pharmaceuticals, clothing dyes, dental services, etc

so... 1 in 500 rafts will be industrial and 1 in 200 rafts would be medical treatment centers

Earth ==> land: 148,326,000 km2 / water: 361,740,000 km2

figuring 'Goldilocks band' as not too equator not too polar is 80% of that, allowing 100 km2 as each village's exclusion zone (albeit mobile) there's room for about 2,893,920 villages and up to 2,893,920,000[2] humans

WELCOME TO EARTH AT 250M-year

POPULATION 2.9 BILLION

=+=+=+=

[1] handwaved uber-tech -- my latest contribution to terminology about almost-in-reach technology upgrades circa 2050; such as CRISPR but (somehow) without all those annoying zombie-inducing viral bio-weapons;

[2] ((361,740,000 * 0.80) / 100) * 1000 ==> 2,893,920,000

uhm... forgot this bit to type in...

WELCOME TO EARTH AT 250M-year

LAND POPULATION 2.9 MILLION (along a very thin coastal green zone)

SEA POPULATION 2.9 BILLION

29% land all locked together into a nightmarish extreme of here-n-now Australia

SuperAustralia: Alice Springs but without the springs?

Also makes me think the seasteaders really are in it for the long haul. Forget those stupid povo scum with their "wah wah by 2100 it's going to be hot" short termism, they're getting ready for 200,000,000CE when the climate will be really spicy!

Given a choice between living on a volcano and living on a kelp float, I’ll take the volcano any day. It’s far more habitable.

"a nightmarish extreme of here-n-now Australia but without any decent beer"

That's a tautology!

Just because you only get Australia beern after it's been passed by experts doesn't mean it wasn't good before they passed it.

I read that, having just opened a Stone and Wood "Green Coast" lager (brewed in Byron Bay). It's probably not the best lager in the world, but it's pretty good, and the fact it's classed as a craft beer and twice the price doesn't take away from the fact that it's what something like Fosters could be if it were actually good.

My personal favourites are German wheat beers, but there's a lot of good beer made in these parts. You'd think a local wheat beer might take off and perhaps there's a market for that.

JohnS
it already did { 7/12/2002 } ... afterwards, they found structures that were ... um .. not on the detailed plans.
See HERE

Note, biohackers might also create chlorinated plastic rubber trees or some such. They just need to give the plants enough supplemental chlorine as a fertilizer salt to meet the plants’ demands. Yes, seawater has chlorine in it. Why do you ask?

Where does the surplus sodium end up if the biological process is disassociating the salt into its elemental components to sequester chlorine atoms? Hmmm, stage trees?

As for the plastic-eating bacteria mentioned in other comments, quelle surprise. Hydrocarbon-derived plastic is a high-entropy food/fuel and evolution will result biological entities that can derive sustenance from such food resulting in enough energy for successful replication of their genome. It's what happens to oil slicks in seawater, bacteria chew them up and spit them out over time. Plastics in the oceans are just a more chewy version of an oil slick.

anyone interested in free water, New York City is getting five fracking inches dumped today... drive up a truck and carry off as much you want... come back for seconds! thirds!

Heteromeles 345:

I'm assuming handwaved uber-tech permitting certain improvements to provide better attributes to kelp including strength-density-durability... given the choice of a barren mega-continent or a life-filled planet-spanning ocean, not much reason to endure the deserted parched lifeless interior (98%?) of Pangea Ultima...

as to living on a volcano, most of 'em are dormant 99.5+% of their existance... so yeah me too... till it starts getting all drippy with lava

Heteromeles 338:

"when one species invades a new habitat"... much as rats -- species millions of years old -- colonizes human cities (a mere few thousand years) it will adapt by mutating into specialized roles and/or specific food niches like this...?

https://www.youtube.com/watch?v=xvs8zGLJe-U

Since much of Edinburgh is a world heritage site, what will they do IF something like what happened to Notre Dame Cathedral happened there?

It did (in 2002).

This might be a handy detail, at some point. https://phys.org/news/2023-09-chilling-tale-flies-self-amputation-survival.html

There's a lot of really clever things you can do with wood and pottery, but I think anything with large-scale use of metal (say, an 18th-century age-of-sail civilization) is out of the question because it would have atmospheric effects. We can measure the amount of silver smelting the Roman empire did by looking at atmospheric lead levels in ice cores. However, Antarctic ice cores only go back 800,000 years, so you might be able to sneak in something back at the time of the dinosaurs.

(We've found ways to measure atmospheric CO2 levels even further back, but I don't know if they'd work for other chemicals. It probably rules out any ancient industrial civilizations, though.)

I also once read an article that said that even agriculture had a detectable impact on climate - there was a change in atmospheric CO2 trends which matches up with when humans first started clearing land for agriculture. But I don't know if we'd be able to recognize such a change as intelligently-caused that far back.

Re: fungi and bacteria.

About fungal hyphae growing for kilometers. They do, but not the way you might think. Two mushrooms growing a kilometer apart are unlikely to have a hypha growing between them. Most hyphae are less than 20 microns in diameter, and they branch, so it’s quite possible to have a kilometer of fractally branching hyphae within a few cubic inches of soil.

Microbes that munch stuff. Aren’t they great? Why do we need fungi and termites anyway? There are two answers to this. One is that the biosphere could do most things with prokaryotes alone, so we eukaryotes aren’t necessary. The second is that things tend to go faster when eukaryotes do get involved because we can move stuff longer distances. For example, a fungus can suck up water in one spot, get sugar from its plant partner in another spot, and use both to to munch the nutrients out of a dead bug in a third spot. Unicellular microbes are limited to whatever is in their immediate vicinity, so if they don’t have everything they need, they’re stuck.

So it’s great that microbes can break down plastic, but until eukaryotes help them get everything they need, it won’t be very fast. That’s why we need industrial bioreactors for our waste stream, and for fungi, worms, termites, and their buddies to become symbiotic with the plastic degraders in the wild. The last will likely take awhile.

Er, some fungi's myclelia DOES go considerable distances, often bundled into rhizomorphs - Armillaria mellea is one such. Metres in a straight line is pretty common; probably not kilometres, but I wouldn't put anything past the fungal kingdom.

And, in water, the nutrient transport isn't the same issue; I can easily see bacteria breaking down polythene or PET floating on the sea without direct assistance from eukaryotes. And, equally, putting the gene into common saprophytic eukaryotes could easily lead to them becoming widespread.

re: Pangea Ultima.

So far it looks like commenters think PU is a giant Australia, red, hot, and dead. It’s crossed by caravans of emus carrying precious cargos of good beer and pickled mushrooms between underground oasis settlements. And because it’s so hot, the black-skinned people guiding the caravan are wearing loose, sun blocking robes, carrying large parasols, and wearing thick-soled sandals to protect their feet from the burning sands. What did I miss. Boots for the emus? Well, more than that actuality.

Let’s assemble PU by monologging about volcanoes and plate tectonics. There are a few well-known ways to get volcanoes. One is where oceanic crust subducts under oceanic or continental crust. The melted crust flows up, forming a line of nice, conical, boomy volcanoes. This is where most of the volcanoes in the Pacific Ring of Fire come from.

Another way is where crust rifts, as along the mid ocean ridges and the African Rift Valley. These form volcanoes where tectonic plates widen.

A third is where mantle plumes form hot spot volcanoes. These tend to form shield volcanoes on oceanic crust, although Yellowstone is over a hot spot.

So when two continents collide, wha kind of volcanoes form? They don’t really. Instead, the tendency is for a really high mountain range to form, something like the Alps, Himalayas, and the Tibetan Plateau, where India is grinding under Asia.

So when continents collide to form Pangea, you’d expect volcanoes first as the ocean between the plates is subducted. Then, as the continents themselves collide, you’d expect the volcanoes to stop and giant mountain ranges to form, with huge rain shadows behind them, more like Central Asia than Australia. That’s what is in the center of PU. Giant mountains catching rain and sourcing rivers that water the lowlands.

Speaking of which, where are the emu caravans getting their beer? Well, now that you know about the mountains, it should be obvious that quaint mountain fortress-monasteries are brewing the beer, shipping it out to the lowlands to trade for salt and natron from the dry lakes.

Possibly some of the monasteries are preparing to give birth to a New World Order, but they’re having problems getting their emus to wear combat boots, emus being emus. But that’s another story entirely.

You might be surprised at how little metal was used in sailing ships, factories etc. in the first half of the 18th century, except for armaments (which are not needed for a civilisation). Even in the second half, iron and steel were only just starting to take over from other materials. The 19th, I will give you.

https://www.statista.com/statistics/1305105/iron-production-europe-historical/

Two legs good - four legs bad? What do you have against camels?

At least until the mountains wore down, I can easily see flood plain civilisations in a Pangaea - from rivers that make the Nile and Ganges look piffling. Indeed, I suspect such civilisations would have to be migratory to avoid being washed away.

That’s why we need industrial bioreactors for our waste stream, and for fungi, worms, termites, and their buddies to become symbiotic with the plastic degraders in the wild.

Arguably, ruminants are just industrial bioreactors on legs. (And carnivores/omnivores break down and scatter the second-order byproducts of the bioreactors.)

OGH: Over on David Brin's blog, Dr. Brin said: "If he were here today, Smith would be a flaming Democrat."

Besides my *USANian guess, I said I'd go and ask what you think.

Thank You,

Keith

"While I lack significant knowledge of British politics, I'm GUESSING Smith would today possibly be either a supporter of the Scottish National Party (SNP), or the Liberal Democratic party (LDP)... If he were pragmatic (committed to forming governments) and not ideological, he might support the moderate wing of the Labour Party (LP) instead of the LDP. From what I read in *Charlie Stross's blog, the UK Conservative Party (CP) appears to be adopting some of the GOP's less reputable characteristics, so I would guess he wouldn't be a Tory.

"Smith" is one of the most common surnames in the UK, so this really lacks any form of context. Wikipedia disambiguation page for John Smith.

Given the large numbers of cattle that die from eating plastic, bioengineered varieties that could 'digest' it might well be a marketable proposition.

What "Smith" are you talking about? (You failed to link back to the previous comment.)

Greg Tingey @ 349:

JohnS
it already did { 7/12/2002 } ... afterwards, they found structures that were ... um .. not on the detailed plans.
See HERE

I didn't see that when I visited in November 2004. It must have been a section Cowgate I didn't walk.

I know I went up Candlemaker Row from Cowgate head (to Greyfriars Kirk), and then somehow ended up on Holyrood Rd where it ends between the Parliament Building and Dynamic Earth ... on my way up to Arthurs Seat where I photographed the sunset over the castle before discovering the climb up from the east side is MUCH EASIER ... I'd have got there BEFORE sunset if I'd just walked around the edge of the park to the other side.

I really want to visit again. I only had 15 days & split it between Glasgow, Fort William/Malaig, Inverness & Edinburg. IIRC, I only had 3 days in Edinburg.

I'd really like to have a couple weeks just for Inverness and another couple (or longer) for Edinburgh

... and this time get there IN TIME to photograph "the train" at Glenfinnan (which was the reason I chose Scotland for R&R in the first place). I'd like to spend a week just in Glenfinnan photographing "the train" from various viewpoints.

If I understand the schedule there's a season when "the train" makes two runs every day.

Pushing IQ45 back .....
"Flipping" A Trump co-defendant pleads guilty - a good start?

Charlie Stross @ 352:

"Since much of Edinburgh is a world heritage site, what will they do IF something like what happened to Notre Dame Cathedral happened there?"

It did (in 2002).

So what did they do AFTER to preserve (restore?) the fire damaged buildings?

There's been quite a lot of news about how France is restoring Notre Dame in all its medieval glory (plus recreating the 19th century spire). How did Edinburgh handle its disaster?

Heteromeles 357:

given your labor-management issues with them emu nasty buggers voting to set up Pangea Ultima Local 265, Transportation Union, Beer & Pizza & Pickled Luxuries Delivery Workers United ... you could always bring in scabs from overseas... ostrich 'contractors'?

Charlie Stross @ 364:

What "Smith" are you talking about? (You failed to link back to the previous comment.)

My first guess would be Adam Smith, beloved of libertarians & right-wingnuts everywhere. Frequently quoted, rarely actually read.

It’s crossed by caravans of emus carrying precious cargos of good beer and pickled mushrooms between underground oasis settlements. And because it’s so hot, the black-skinned people guiding the caravan are wearing loose, sun blocking robes, carrying large parasols, and wearing thick-soled sandals to protect their feet from the burning sands. What did I miss. Boots for the emus?

The likelihood that if it's hot enough that emus need boots (or sandals), the chances of good beer staying good aren't very good. Skunky beer, more likely.

OK, science fiction is all about willing suspension of disbelief, but readers require at least a modicum of plausibility, and intentionally treating good beer like that is a bridge too far… :-)

My first guess would be Adam Smith, beloved of libertarians & right-wingnuts everywhere. Frequently quoted, rarely actually read.

Rarely read because actually reading him would produce more quotes than just the famous metaphor about an invisible hand. A sampling:

No society can surely be flourishing and happy, of which the far greater part of the members  ar e poor and miserable.

Civil government, so far as it is instituted for the security of property, is in reality instituted for the defence of the rich against the poor, or of those who have property against those who have none at all.’

This disposition to admire, and almost to worship, the rich and the powerful, and to despise, or, at least, to neglect persons of poor and mean condition … is … the great and most universal cause of the corruption of our moral sentiments.

It must always be remembered, however, that it is the luxurious and not the necessary expense of the inferior ranks of people that ought ever to be taxed.

Science is the great antidote to the poison of enthusiasm and superstition.

But the rate of profit… is naturally low in rich, and high in poor countries, and it is always highest in the countries which are going fastest to ruin.

The interest of [businessmen] is always in some respects different from, and even opposite to, that of the publick … The proposal of any new law or regulation of commerce which comes from this order … ought never to be adopted till after having been long and carefully examined … with the most suspicious attention. It comes from an order of men … who have generally an interest to deceive and even to oppress the publick...

The necessaries of life occasion the great expence of the poor. They find it difficult to get food, and the greater part of their little revenue is spent in getting it. The luxuries and vanities of life occasion the principal expense of the rich; and a magnificent house embellishes and sets off to the best advantage all the other luxuries and vanities which they possess … It is not very unreasonable that the rich should contribute to the publick expence, not only in proportion to their revenue, but something more than in that proportion.

Labour was the first price, the original purchase-money that was paid for all things. It was not by gold or by silver, but by labour, that all wealth of the world was originally purchased.

I have never known much good done by those who affected to trade for the publick good.

A merchant, it has been said very properly, is not necessarily the citizen of any particular country.

The likelihood that if it's hot enough that emus need boots (or sandals), the chances of good beer staying good aren't very good. Skunky beer, more likely. OK, science fiction is all about willing suspension of disbelief, but readers require at least a modicum of plausibility, and intentionally treating good beer like that is a bridge too far… :-)

Well, it's equally not worth accepting the popular reporting on this research either, is it? I mean, it gets up to 50oC occasionally in mid-summer, therefore no mammals can survive? What about the other eleven months? And, well, living in a hole in the ground when it's hot?

So simply run the emu beer caravans in the spring, and save the combat booties for mountain snows.

Anyway, the other Aussie-themed choice was a kangaroo caravan, and I think that'd be even worse for the beer. You want maybe wombats?

You want maybe wombats?

Definitely need wombats. Everything is better with wombats.

According to one of my profs who did a sabbatical in Australia (in the 80s), wombats were responsible for a surprisingly large number of fatalities, because they're apparently the right size to cause loss of control if you hit one at highway speeds. He described them as 'like furry rocks on highways, but slower'.

Well it might not be adequately themed, but the Australian deserts are home to the largest feral camel populations in the world including the only “wild” dromedaries known. Preadapted and all that.

Wombats are always cool, of course, but you always imagine wombats with tool belts rather than cargo… Roadkill wombats are among the saddest things to see, like Paddington Bear taking a nap after too much or that “aged” marmalade, but not.

@OGH et al: My apologies- too much haste. Yes, Adam Smith: the Scottish Proto-economist.