A New Twist on the Aquatic Ape Theory

[AnastasiaH]

Neat story.

Probably a trivial matter, but what about the way your skin goes all wrinkly in the bath and if you swim too often, you start to get all sorts of skin problems? Wouldn't that indicate that maybe spending hours standing still in water wouldn't be that practical?

Also, I thought the current thinking was that H.Sapien didn't evolve from Australiopithecus (sp?) but that the two were related branches of the same family tree?

[AlgisKuliukas]

We are also the only surviving primate to have sacrificed high mobility in trees. That makes me wonder what it is about the terrestrial environment that forced that sacrifice and what that had to do with our body plan.

And I would agree with your curiosity and it's probable conclusion. It's not black & white. The way i see it we came down from the trees and eventually became 100% (to the nearest integer) terrestrial but we also did enough swimming and diving to change our phenotypes.

In a rough sense, one can assess relative significance of living relations vs. abiotic factors by looking at what seems significant in other species. Consider any other animal and see if you can describe its adaptation without considering its particular relations with living things it habitually eats, and other creatures that habitually eat it. The differences between species generally reflect different methods optimised in these relations. Consider the porcupine, impala, baboon, leopard.

But there are also gradients of adaptability. Consider arboreality. Is a human more arboreal than a baboon? Is a baboon more arboreal than a gorilla? Is a gorilla more arboreal than a chimp? Is a chimp more orboreal than a bonobo? What about orang utans? gibbons?

It's not black and white. there are gradients. In terms of moving through water, I put it to you that we are the best of the apes and probably the best of all the primates too - how did that happen if not by natural seelction?

Of what use is "smartness" when it's (a) no more developed than in a chimpanzee (b) in a strip environment penetrated by ground predators? In what sense could your aquatic ape be said to be optimised in its gallery forest environment? The first optimisation there would be in tree-climbing, the most conspicuous ability our body-plan isn't adapted for. In competition between a chimp and an aquatic ape in a gallery forest, who would you back?

Chimps are pretty smart, I think. It was optimised in the sense that it was very able to climb trees, it was very able to wade bipedally through shallow water and it was very able to move (however) on dry land during the dry season. I doubt many species in that niche could do all three as well.

A don't like to refer to them as "aquatic apes" because they were in no real sense aquatic - but I'd back a "river ape", or a "wading ape" against a chimp any day.

I did agree that modern man living in high density can remove dangerous crocs but these are generally the last surviving predators on humans in an area where human density is increasing, basically because water is their element.

But what about egg/infant predation? Do you deny it's a possibility?

My gut feeling is to agree with that [scepticism about shar predation], but it's a reflection of how very little "aquatic" an aquatic ape would actually be. If you consider a really semi-aquatic mammal like a seal, there sharks are habituated predators and their prey is well adapted to escape from them.

Speaking of "staying in the shallows" you should maybe take OHSU's point more seriously, that humans are hopeless at moving rapidly through shallow water. You discounted his experience as a one-time lifeguard as expertism, OK but surely you have tried to run quickly into the sea yourself? When the water is shallow you have to run in a funny high-kneed way and yet sooner than later, the sea trips you up. Or you can preempt that by diving into the water well before it's knee-deep. If there were a land-predator after you, you wouldn't stand a chance because its natural bounding motion doesn't involve moving its limbs within the water against the direction of running, as with humans. In addition to modelling unreasonably abiotic stressors on human evolution, the AAT seems to model our ancestors in unreasonably static conditions.

Exactly. If they're not that aquatic the shark threat disappears.

Abouts OHSU's point - why would they need to move through shallow water quickly? I doubt there was any major predation threat in coastal shallows. Most of their time spent there would haave been rather leisurely looking for crabs and other shellsfish, as far as i can imagine.

I like that concept of Nature "cajoling" a population along changes. Also I don't see a problem with your logic. But I do have queries about the realism of the picture you sketch, around pointe e) f) and g). It's true some savannah habitats are prone to flooding, for instance the Zambezi valley. As we speak, two children are trapped in Zimbabwe by such floods. A couple of years ago, thousands were trapped by floods in Mozambique. What do the modern humans do when trapped in this way? Do they wade from tree to tree? What is the point? They might as well stay and starve where they are. Are trapped bipedal humans equipped any better in such circumstances than a chimp? How much adapted competence did humans display during the Katrina floods?

It's interesting (sad, but good for my idea ) to hear that African rivers in savannah areas actually flood even today.

Maybe "staying where they are" is the best strategy for modern H sapiens but I doubt it would have been before the genus Homo had even evolved. If they fed on fruits, nuts and shoots from trees then, clearly, they'd have been better off trying to wade through the water to get to another clump.

That "leisurely beach dweller" pictures an unlikely context for any African creature. I agree our skin is particularly prone to being torn but that can be justified as an adaptation that on the one-hand was permitted by a weapon-using defense that avoided body-contact with a toothed antagonist, and necessitated by the need for a water-efficient evoprative cooling system in emergencies.

Why?

I think wepoan weilding is still a high risk strategy. Some selection would have occured to act as a back up when lacerations and other injuries occurred, I feel.

Don't bother really. My problem with Wheeler's theory (I only know it from a New Scientist article by him some time back) isn't about circularity or parsimony, it's the same as my problem with AAT: it unrealistically foregrounds abiotic factors. For example, on the face of it the carotid rete is connected with emergency escaping from predators. Although I've heard that hasn't been substantiated. So if one wants to hypothesise something about hominids not having a carotid rete, the obvious context to build, is that of alternative prey-sort to animals that do have it.

Look, I think there are so many problems with the idea I'm disgusted it not only got published in the literature but was being taught as orthodoxy at UCL when I was there in 1999. And I can't get the wading stuff published! It's so depressing.

OK, then what did our ancestors 2.6 mya (your time stamp) do with excellence? According to the AAT, they adapted the hominoid body form quite radically, to achieve a doubtful advantage in walking slowly through water of a narrow-range of depths in two very particular biomes; rocky littorals and riverine forest. To the extent these ancestors were hypothetically aquatic, they sure wouldn't attract the crowds to a zoo the way seals, dolphins or otters do. Except maybe to laugh at them.

Look I can understand you scepticism but perhaps you are not taking on board fully the fact from population genetics that very slight selection can and does make profound phenotypic change in very short spaces of time.

If by "cortical breath control" in diving, you mean the ability to automatcally stop trying to breathe when your face is under water i put it to you that every vertebrate must have that. As a kid I recall seeing a lizard in a creek near the Molonglo, lying on the bottom near some trout. We though it was dead until we dropped a stone in the pool. Cortical breath control?

Again, I understand your scepticism. We've all seen dogs and cats and all sorts of creatures do this so we're pre-conditioned to think that it is the mammalian norm and no big deal for us. It might well be. But have you ever seen a chimp doing it, or a bonobo? or a gorilla? or an orang-utn? or a gibbon? I've not.

I keep reminding - it's the comparison with the apes that counts because we are apes. If we are far better at cortical breath control than they are - and that is what all the anecdotal evidence indicates - then that needs a Darwinian explanation.

Believe me, I know how you feel. [about repeating the argument above] But maybe your 100x point is wrong? To survive in an aquatic environment demands a performance-envelope adequate for that environment. There are no feet-adapted whales in the Sahara, even though the most miserable whale-feet would be better that what cousin ocean whales have.

Absence of evidence is not evidence of absence. Humans, it seems, had an opportunity to live at the coasts without any great previous competition and exploit it better than any other primate had before. That doesn't mean ever taxon has had the opportunity to exploit every habitat on the planet.

Those anthropologists. Don't get me started. But isn't it up to AAT proponents to do those studies? The problem would be regaining the trust of the chimps one had tried to drown. A wet angry chimp would be such a downer.

See, that's what they say. My response is to say: instead of asking why so-called AAT proponents are such bad scientists, why not ask why no good scientists has ever been interested in the possible effects of moving through watere on human evolution? Why does it have to be all about "us and them"? Anthropologists should be interested in all aspects of human evolution, not just the dry aspects. When did that rule get invented?

If anything the "man the mighty hunter" arguments seem to be creeping back into favour, after American paleo-anthropologists shot it down in the 1970s as a precursor to building their own narrative, once they had their own fossils. But the hunting hypothesis and "APT" are different in a sense that can be expressed as a curiosity: hinting is all about what hominids held in their right hand, whereas an APT is also about what was in the left hand. The initial step in welding tools to hominids according to the APT would have been the use of a defending stick to stop a predator's charge, take the initiative from it and make it vulnerable to counter-attack. To this day, predicts the hypothesis, a human will tend to use a "stopper" or shield weapon in the left hand and a stiking weapon in the right.

At the very least "anti-predation theory" must always have figured pretty prominently in the thinking of any savannah theorist.

Yes one would think so wouldn't you. But hunting hypothesis interest has glommed around aggressive male violence and defense has just been a stepping stone to that interest.

I really don;t think there are as different as you think. Although i might be wrong.

You serious?[about being an Anglican] Isn't that a bit of a contradiction? You believe in God and evolution?

If I accepted AAT as part of evolution, then I would be accepting an origin narrative of self-creation in Eden. There are plenty of Christians who have "no problem" with evolution and I'm sure there are plenty of atheists who have a problem with AAT. But I riskily predict there are relatively few enthusiastic proponents of AAT who are church-going Christians. Not that it's evil or anything like that; it's a fascinating folk-tale of the atheist clade.

Best wishes
Jay

"Self-creation in Eden" - tell me more about how that works.

But if those Christians are true to their beliefs, they think Christ was born from a virgin and ascended to heaven after his "death". How can such beliefs be compatible with evolution?

Algis Kuliukas

[DavidMcC]

A couple of years ago, thousands were trapped by floods in Mozambique. What do the modern humans do when trapped in this way? Do they wade from tree to tree? What is the point? They might as well stay and starve where they are. Are trapped bipedal humans equipped any better in such circumstances than a chimp? How much adapted competence did humans display during the Katrina floods?

What if we're actually adapted to rushing into fairly shallow, almost still water and grabbing as much seafood as we can before the crocs stir? No torrent resistance or long-term water resistance required. The food gathered must have been vital for this AAH to be valid, but it might well have been so. The earliest fossilized human meal found in the Great Rift Valley was fish.

[AlgisKuliukas]

The food gathered must have been vital for this AAH to be valid, but it might well have been so. The earliest fossilized human meal found in the Great Rift Valley was fish.

Have you got a reference for that David?

Algis Kuliukas

[DavidMcC]

Have you got a reference for that David?

I have been searching the internet and books, but can't find anything. It was on a TV program I saw many years ago, I'm afraid, but I definitely didn't imagine it!

[AlgisKuliukas]

Neat story.

Probably a trivial matter, but what about the way your skin goes all wrinkly in the bath and if you swim too often, you start to get all sorts of skin problems? Wouldn't that indicate that maybe spending hours standing still in water wouldn't be that practical?

Also, I thought the current thinking was that H.Sapien didn't evolve from Australiopithecus (sp?) but that the two were related branches of the same family tree?

Aren't those wrinkles due to the soap? I can't remember ever getting wrinkles swimming in the sea, besides, has anyone ever died of skin wrinkles?

My understanding is that most paleoanthropologists are agnostic about whether australopithecines were ancestral to human beings. They certainly appear to fit the bill in terms of timescale and they're kind of appropriately intermediate in being bipedal and yet small brained.

Technically, the likelihood of any fossil hominid being ancestral to Homo sapiens is very small but on the other hand something living at the time of the australopithecines clearly was ancestral to Homo sapiens and if it wasn't, say, Australopithecus afarensis exactly, it's likely to have been something similar.

Finally, I don't think this really matters either way as far as waterside hypotheses of human evolution go. Some proponents, like Marc Verhaegen, would probably argue that australopithecines have nothing to do with human evolution and that the so-called "AAT" is only to do with the waterside adaptations of the genus Homo. Hardy originally and later Morgan did think that perhaps australopithecines might have been this "missing (more aquatic) link" but the evidence really does not back that up. Certainly almost every proponent of any waterside hypothesis of human evolution today would argue that Hardy got his timescale very wrong, understandably for what was known before 1960.

Personally, I agree with Verhaegen that most of the characteristics of ape-human divergence (e.g. nakedness, fat, large brain/small teeth) happenned at the coasts from around 2.5my onwards and are only associated with the genus Homo. On the other hand, I disagree with him though, and agree with Morgan, that bipedalism is also a big part of this idea because it too is best explained by postulating a differential between apes and humans in moving through water. It is complicated by the possibility (actually I think it is now a probability) that the last common ancestor of Pan/Gorilla/Homo was probably already a climbing-wading partly bipedal ape, but even this complication can be resolved in a waterside context if we merely assume that whereas the ancestors of Homo continued to live in waterside habitats, the chimps and gorillas stopped doing so. It's probably much more complicated even than that, but I won't elaborate any further here.

Anyway, I've been studying this thing now for ten years (how sad is that!? ) and I'm more convinced than ever that the idea is basically right as long as it is scaled back a little, not misrepresented and people just realise how little selection is needed to make profound and rapid phenotypic changes in populations.

Algis Kuliukas

[Jayjay47]

But there are also gradients of adaptability. Consider arboreality. Is a human more arboreal than a baboon? Is a baboon more arboreal than a gorilla? Is a gorilla more arboreal than a chimp? Is a chimp more orboreal than a bonobo? What about orang utans? gibbons?

It's not black and white. there are gradients. In terms of moving through water, I put it to you that we are the best of the apes and probably the best of all the primates too - how did that happen if not by natural selection?

It's not uncommon for a whole troop of baboons to infest one tree and a single baboon, especially a guarding one, seems if anything to prefer sitting in a tiny tree. So it seems to me that humans are a lot less arboreal than baboons and by extension, all other primates. In particular, we can't avoid a leopard by climbing a tree whereas baboons stand a good chance, even at night, because they are lighter plus the males are dangerous quick biters.

A don't like to refer to them as "aquatic apes" [in a gallery forest] because they were in no real sense aquatic - but I'd back a "river ape", or a "wading ape" against a chimp any day.

OK, neither of us have real evidence here. But a gallery forest is by definition a narrow strip, abutting on savannah. Therefore hunting predators can enter it. If they encounter a "wading ape", how would that ape be in a stronger position than an arboreal chimp?

But what about egg/infant predation? Do you deny it's a possibility?

The problem with preying on croc eggs is that several species would presumably have an interest in that mass of protein, including wading birds, water monitors and snakes. The crocs don't make predation easy. The mommy crocs lay their eggs in inaccessible places and then lay up near the eggs. I wouldn't want to hunt for croc eggs and I don't think I'd be more successful at that than other less "smart" animals.

About OHSU's point - why would they need to move through shallow water quickly? I doubt there was any major predation threat in coastal shallows. Most of their time spent there would have been rather leisurely looking for crabs and other shellfish, as far as i can imagine.

That's a very interesting point. It really goes to the heart of the question whether one should model creation as being active during leisurely activities or in extremis, as when a brace of lionesses come loping out of the coastal dunes. I'm all for constraints or performance envelopes but your concept is so foreign to me, I'd have to think about it a bit.

I think weapon wielding is still a high risk strategy. Some selection would have occurred to act as a back up when lacerations and other injuries occurred, I feel.

But what if the advantage from the backup hairy skin is more than compensated by the disadvantage of then wasting precious water that evaporates without directly cooling the blood? I mean, one difference between a weapon-using hominid and say a sweaty zebra, in establishing the optimum skin, is that a hominid would not need to come into contact with a predator if fighting. Injuries also arise from fleeing which buck do but I argue, hominids didn't flee, that instead our ancestors defied predators.

Look, I think there are so many problems with the idea [Wheeler's cooling-by-bipedal orientation] I'm disgusted it not only got published in the literature but was being taught as orthodoxy at UCL when I was there in 1999. And I can't get the wading stuff published! It's so depressing.

Yes, his theory had a smooth ride. He had "data"- as I recall, in the form of a graph showing that as the sun's orientation relative to the body changes, so it reaches a minimum for a standing person, at midday. Whereas for a quadruped, it's a maximum then. But we know that by reason, it could not be otherwise. But while we are whining, I can't even get a single person to seriously entertain the antipredation hypothesis, whereas there must be thousands who accept the AAT. Plus there is a penumbra of uncommitted professional scientists who keep it in play as an interesting possibility in the toolbox of what should be considered.

By the way, you have been quite patient with my free-loading on your topic to promote my own. I eventually set that up as the separate topic "A new twist on the Savannah theory" -still freeloading in a sense.

Look I can understand you scepticism but perhaps you are not taking on board fully the fact from population genetics that very slight selection can and does make profound phenotypic change in very short spaces of time.

I don't think the creation is about change so much as incredibly cunning competencies, reflecting a deeply crannified topography of what might be called "design space". Speciation happens when a population finds itself at the mouth of a sort of supertube top in this space. Like snakes and ladders but without snakes or without ladders, depending on which way you hold the board up.

"Self-creation in Eden" - tell me more about how that works.

Well you have these waterside apes gently pottering amongst the rocks like on a Sunday outing. That is Eden. The antipredation hypothesis has a brace of lionesses appearing from between the dunes. I'd say that is pre-Eden. Again, Who or What is creating or "adapting" those waterside apes? As I understand the AAH, I'd say "nothing" or "evolution". But in terms of the Antipredation hypothesis, one would say, the relation between lioness and ape, or maybe, the web of living relations involving to first approximation, the lion, hominid and zebra (as alternative prey). An Islamicist might call these the Potter's hands. Whatever, there is agency and it's outside of the population.

Best wishes