So here are the problems: --What swamp? It's got to be a very, very special one where the water is shallow enough to wade in, but somehow clear enough that the Nile crocodiles can't sneak up on the wading apes (http://www.pressreader.com/south-africa/the-mercury/20150702/281694023437941) (Note the part about how many people get attacked by Nile crocs because they think that crocs don't attack in shallow water). That's getting awfully picky, and I'd rather have someone from Africa comment about how widespread such swamps are. --There's no (known) bipedalism gene, so switching from quadrupedal to bipedal will take awhile, as it involves changes to multiple genes. That's a long-lived swamp too, incidentally. --Bipedalism slows you down a bit, although it might add to endurance. Outjogging a lion is a tricky operation, and I don't think you could pull it off against a hyena or wild dog. --Obligate human bipeds go into swamps generally as a last resort, not a first one, because wading through mud sucks. I've never worked in a true swamp, but I've done plenty of marsh work, and it is NOT fun. There are some people who like it, but I'm not one of them.
Now, if you want a cheaper answer that gets rid of the aquatic silliness, I think Runner's World accidentally nailed it with https://www.runnersworld.com/run-the-numbers/outrun-the-worlds-most-dangerous-animals (note that you may have to sign up for spamnation to get to this article. Sorry). I stumbled across it when I was looking for chimp top speeds. There are two critical points here: 1. A bunch of predators can outrun humans. Bipedalism isn't about speed. 2. You can still escape a threat if you have a good-enough lead distance, meaning you can see the threat something like 100 meters away and there's a tree nearby, which is what open savannas are all about.
So if you want the evolutionary story, I'd suggest the sentinel scenario: standing upright gives you a better view, so that you have a better chance of spotting dangers. Living largely in a savanna (as opposed to a dense forest or a grassland) gives you a reasonable chance of spotting a threat at a good distance (the open part) and making it to a nearby tree before the lion beats you there (the tree part). It won't work against a leopard, but being up a tree with a couple of your mates, all of whom are freaking out and ripping branches off to throw, will probably give the spotty kitty pause about coming after you, and will give her multiple targets if she decides to do it anyway (lowering your odds of dying).
Unlike you (most likely) I have gone quadrupedal, back when I played capoeira. In capoeira, only your hands, feet, and head are supposed to touch the ground, but there's a lot of floor play where you go onto all fours (to kick someone in the head or dodge a kick to the head, for example), and it's not as hard to move in that position as you might think, although it's not as fast as running and you do have to be flexible to accommodate your long legs. Unlike you, I don't have a problem with a quadrupedal/bipedal transition, if the utility of going bipedal isn't about increasing speed but increasing your starting distance from threats, and so long as bipedalism doesn't interfere with your ability to quickly climb a tree (which, according to the analysis of the skeleton of the fully bipedal Australopithecus afarensis, it didn't, although it arguably does now).
Contrast that with ol' swampy ape, bipedal but crouched in the soup all day, face level with the water while she feels around for those so-nutritious rhizomes, clams, and crayfish you were going on about (you have tried to actually do this, no? I have rooted around in a marsh, at least. I won't mention the mosquitoes or the humidity either). When a crocodile comes up behind her and grabs her ass, she has no warning, because her face was level with the water as she feels around with those too-short arms. Having longer arms would be more useful in this situation, but no, she needs longer legs, because she's going to, erm, splash awkwardly through the muck away from the croc, because bipedality works better in the water. Yeah. There's probably a reason the croc has very short legs, a powerful tail, and adjustable buoyancy. That's what works best in a swamp. If you've ever watched those videos of lions hunting in the Okavango Delta (which is also a swamp), you'll see that they're not slowed down that much by water either.
Your riposte, sir?
]]>What about me? AS I SAID, I have lived in some relevant areas - try Choma, Chilang and Mansa - and that was BEFORE the crocodiles were almost completely trapped out. AS I ALSO SAID, try Lake Bangweulu. Look it up. There are others. I will pay you the courtesy to assume that you haven't started to troll, but it's not being easy.
And, AS I SAID, the upright position gives an advantage for the members of the group who are on watch. You ARE aware that's how baboons and others operate, aren't you?
And, yes, I have waded through such things, felt for molluscs, and been involved in fish driving in exactly the conditions I described. And I have waded off the coast of Kenya (I was trying to swim, but it was too shallow), and could have picked up 10 Kg of sea slugs etc. off the bottom in an hour. In all cases, I found my bipedalism a great help when doing that.
No, I do not give this hypothesis more than a good chance of being partially right, but (like Elaine Morgan) I get sick of the hypocrisy of the establishment that applies different standards to its favoured dogmas to everything else.
Now, let's deal with that runner nonsense.
"You can still escape a threat if you have a good-enough lead distance, meaning you can see the threat something like 100 meters away and there's a tree nearby, which is what open savannas are all about."
Thus spoken by someone who has not been there. Most of the drier parts of the savanna do NOT have enough climbable trees to protect a group, even excluding the fact that the development of bipedalism hampers climbing ability. They tend to be very scrubby, impossibly thorny or baobabs, and are often sparse. The climbable trees are concentrated around stream beds, on the kopjes etc. There are reasons baboons tend not to go far from such things, and that's one of them.
And, AS I SAID, I was talking about a dry spell. In such conditions, the trees tend to get sparser, scrubbier and less useful. And it is well-known there have been long periods of wetter and drier spells in the relevant areas.
Also, claiming that, because modern, fully bipedal humans can run AND WALK LONG DISTANCES fairly well, an intermediate form could, is exactly the conflict with Darwinian evolution I am talking about. It's complete bollocks.
As far as I know, not one single animal is known to have evolved cursorial bipedal locomotion in all prehistory in a context where cursorial predators were a serious threat. There is a good evolutionary reason for this, which is that the intermediate form is less efficient. Hopping is completely different.
Furthermore, you ignored the point about food and water. There are MAJOR problems getting enough food towards the end of the dry season for an LCA, chimp or human. Even baboons have trouble. And water: there are good reasons that almost all (all?) savanna mammals either burrow or can walk long distances. In a dry spell, most of the savanna would have been a completely no-go area for the LCA, a chimp or a half-bipedal ape.
]]>As for Elaine Morgan, her problem is the same as yours: shifting context every time someone points out that there's a problem with some part of your hypothesis, just so you can be right. Yes, paleo-anthropologists can (and have) been assholes to people like Louis Leakey, but saying that anyone disdained by the establishment is right is the classic Galileo defense.
Now, we've bounced from swamps to sea coasts, and we've avoided every big swamp (say in the Congo) in favor of...what? The Okavango?
Yes, I read Elaine Morgan's book and liked it. The aliens in my first book were designed as a species became much more sapient as amphibians, and some of the behaviors she described were in there (like women having long hair so that their children could hold onto their heads and get a ride). Then I read the refutations and watched the fossil evidence pile up, and I think that side more correct. That's all. Science is about falsifiability. When that late Miocene aquatic ape fossil turns up, I'll admit I'm wrong.
Finally, it's worth looking at the late Miocene, which is when Antarctica iced up and the world got colder and drier, heading towards the ice ages. This is the time when hominids split off from other apes, and it's also the time when savannas with C4 grasses spread across East Africa. If I wanted to bet on why an ape would settle the savanna, I'd simply guess that its ancestors were there during the previous forest period, and some took advantage of the shift by going bipedal. Why they didn't turn into the pongoid equivalents of baboons I have no idea, but that's evidently what happened.
]]>Which to me is an argument for the seaside, not the swamp. Sentinels only work for groups, and AFAIK there aren't any medium to large reptiles, mammals, or birds that live in swamps and form groups.
As far as I know, not one single animal is known to have evolved cursorial bipedal locomotion in all prehistory in a context where cursorial predators were a serious threat.
When restricted to mammals and ignoring dinosaurs and birds, true. However there aren't any examples of mammals evolving cursorial bipedal locomotion other than hominids, full stop. So it's just as true to say there aren't any examples of mammals evolving bipedal locomotion in swamps. We are highly improbable mammals.
]]>And, yes, we are highly improbable animals (we don't have to restrict it to mammals). My point is that the hypothesis I am describing is plausible, because it doesn't conflict with any known facts, and the establishment's hypotheses (they have several) aren't, because they do. Given the probabilities involved, there had to be some POSITIVE OVERALL advantage over a long period for developing increasing bipedality. The position that "WE don't have to justify our claims because WE are the establishment" just isn't science.
My hypothesis is that it started with foraging under the conditions I described (which fit with what we know of central Africa) and turned into obligate bipedal locomotion later.
Aside to Greg Tingey: I can also explain why the savanna hunter theory for the development of hairlessness is implausible; I favour the reduction in parasite load following the invention of clothing (i.e. skins).
]]>Let's consider your claim. You assert that a savanna-living group of LCAs could run to the nearest trees to get away from predators. Even ignoring is problems with that that I mentioned, it explains the evolutionary pressure to REDUCE climbing ability (which is what happened) exactly HOW?
Look at YOUR first paragraph of #770 and my second one of #776. You are simultaneously claiming that the wading ape hypothesis is wrong because this needs too much evolutionary change and claiming that no evolutionary pressure for bipedalism is needed.
]]>Conversely, I note that chimps show the same general mechanism of walking as humans do. They just don't do it so much because it's inefficient. That's evidence that the mechanism we use for bipedalism was present in the common ancestor of chimps and humans, even though it was quadrupedal. That's one hurdle down for the evolution of bipedality.
Second hurdle: what would cause apes to go bipedal? Global climate change at the end of the Miocene (Antarctica icing up) caused the appearance and spread of savannas in Africa as the climate got drier and colder (not wetter, so fewer lakes, rivers, and marshes), and the savannas replaced the forests that used to be there. The subsequent appearance of a savanna-dwelling ape lineage seems unremarkable, because most animal lineages evolved savanna-dwelling forms in the late Miocene and Pliocene. What's weird is that those apes didn't converge with baboons on a quadrupedal savanna lifestyle, and instead went in for bipedalism.
We both agree that bipedalism slows mammalian runners down, so any argument based on increased running speed from bipedalism is counterfactual. We both agree that being able to see further is the ultimate advantage, because it allows bipeds to avoid danger.
At this point we split. You want to invoke a wading phase in the earliest human ancestry, --despite the lack of fossil evidence for this, --despite the modern diversity of swamp-dwelling primates (which range from lemurs to apes), all of which are quadrupedal and many of which swim, and a few of which gather resources under water, --despite the fact that this environment was present for millions of years when apes were around, and was decreasing precisely when humans became bipedal, and --despite the fact that bipedalism isn't actually that useful in the water, either for swimming through the water, wading in mud, or finding submerged food. You point out that bipedality is useful for carrying food, but then again, bipedality is useful for carrying stuff in any environment.
On the other hand, I see chimps reportedly walking bipedally using the same mechanism as humans do, see a relative advantage to having longer legs and spending more time bipedal in an increasingly open environment, and see a fairly straightforward reason why increasing bipedality would be beneficial as savannas spread. There's no obvious point at which our semi-bipedal ancestors were more clumsy than both apes and humans, so there's no barrier to the evolution of bipedality. If you don't believe me, look at the arm length of Australopithecines. Proportionally the early ones had much longer arms than we do, but they were just as bipedal as we are.
There's no trolling here. The aquatic ape hypothesis just doesn't work as well.
Finally, if you want to understand the dinosaur argument, I'd suggest you read Dawn of the Dinosaurs, which is an accessible history of the evolution of dinosaurs in the Triassic. The relevant points are:
--dinosaurs in the Triassic, when they first evolved, were far from the only large land animals, and the early ones were quite small.
--While I'm not clear that ALL dinosaurs were initially bipedal, that's what I remember. Certainly prosauropods started off bipedal, theropods started off bipedal and (Spinosaurus aside) stayed that way, and I believe that ceratopsians were initially bipedal.
--These small, bipedal dinosaurs showed up in an environment where the largest predators (IIRC) were all large, quadrupedal relatives of modern crocodiles. Indeed, it's not clear, at least to me, why crocs didn't take over the world in the Triassic.
--Birds evolved from theropods in the late Jurassic ninety-odd million years latter, and they inherited their bipedality from their theropod ancestors. Bird evolution is irrelevant to this story.
The only point of bringing up dinosaur evolution in the Triassic is that it's an example of cursorial bipedalism evolving in the face of predation by larger quadrupeds. Therefore it's entirely possible.
I hope this clarifies things.
]]>In this kind of discussion, it seems that some mathematics is necessary. With words, you get into all kinds of problems, such as assuming that because a space is curved, it's essential to postulate extra dimensions to contain it. Or, I suppose, to hold the Many Worlds ...
So to help me understand your posts: is the picture below a correct description of "particles getting into exactly the same quantum state except for the phase"? Can the two particles I've drawn interfere?
If their state has to include position and velocity, I presume not, since in my picture these are different.
]]>This is quite hard to do, actually, and the usual interference experiments - double-slit interferometer and Mach-Zender interferometer - are about a single particle interfering with itself. It is kind of cheating: you don't really know the quantum state of the particle, but since it is a single particle there is nothing to differ. You then split it into two paths, and now the only difference between the quantum states is just the path degree of freedom; when you recombine the paths, this difference disappears, and you have interference.
But it is possible to interfere two different particles. The best example is the famous Hong-Ou-Mandel interferometer. Even then, you have to do a lot of work to synchronize the sources of the particles.
]]>Thanks. So that clears one thing up for me. One can interfere more than one particle: I don't need to think only of double-slit experiments and the like.
Next question: where can I find something that explains what kind of mathematical entity a "world" in the Many-Worlds interpretation is?
]]>https://en.wikipedia.org/wiki/Perchlorate
Naturally occurring perchlorate ... can be found commingled with deposits of sodium nitrate in the Atacama Desert of northern Chile. Also Lubbock, Texas and Florida, produced by lightning discharges in the presence of chloride.
https://en.wikipedia.org/wiki/Perchlorate#Contamination_in_environment
]]>In a nutshell, a world is a branch of the universal wavefunction that hardly interferes with other branches, and that follows approximately the laws of classical mechanics. Mathematically, it is a vector of complex numbers describing a massive amount of particles with very little entanglement between them, and such that its inner product with other such vectors is very small.
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