Baidarka

A while back I posted something here about the aquatic ape theory and I was shot down as if I was the lowest form of flat earth fundie.
Well I just finished reading Elaine Morgan’s “The Scars of Evolution” and I still think that this theory seems plausible.
My affinity for this theory might come from my predilection for water sports and the fact that I spend much of my time on or in the water.
1) Most naked mammals are Aquatic or semi-aquatic.
2) Unlike our primate cousins we have a subcutaneous fat layer which insulates us in the water and provides us with buoyancy.
3) Our extraordinary ability to swim long distances (I’ve been a kayak escort for swimmers circumnavigating Manhattan Island).
4) The fact that sea food tastes so good and is so good for us implies a long association with the sea.
I am not attached to this theory and I will not be insulted by disagreement but I hope that some of you might like to discuss this idea with more then a brusque dismissal.

pz

Not very. It requires selective acceptance of observations that support the claim, and selective rejection of observations that contradict it. It's a dreadfully silly hypothesis, and I've never seen what attracts people to it.

Elaine Morgan has been peddling this stuff for years, and it just gets worse and worse.I seem to spend way too much time sitting on my butt, so I'm inclined to think I'm descended from sessile invertebrates that cling to rocks. I have a friend who likes rock climbing -- so he should favor an 'alpine ape theory'. I'm not sure what the ancestral environment of bicyclists would be.Elephants, rhinos, and mole rats are aquatic? Are otters naked?We have a bit more fat, but it's probably more a consequence of neoteny than any functional cause. The fat we do have is completely inappropriate for insulation. For one thing, it's in the wrong place -- having a nice thick belly does no good if you are losing heat from your ankles, elbows, and head. For another, human fat is most definitely not a useful insulator. It's well vascularized, and so is just another region where body heat is rapidly dissipated. Animals with insulating layers have something we don't: vascular countercurrent exchangers to retain blood heat.We might be better at swimming compared to a chimpanzee (although I haven't seen anyone try to train a chimp to swim, so I could be wrong), but we aren't particularly good at it. People swimming around Manhattan are examples of our species' interest in novel and even extreme experiences, like people who sit on flagpoles, go ballooning, or engage in dance marathons. They aren't evidence of ancestry.I'm trying to imagine what environment would be ruled out by this logic, and how it could be extended. Is there any environment which produces plants and animals that we do not like to eat?

I like clams and potatoes, so my ancestors must have been subterranean?
I haven't been too brusque, but all you're going to get is a dismissal. Sorry.

Mageth

1) Most naked mammals are Aquatic or semi-aquatic.

Not all aquatic mammals are "naked", and many (if not most) naked mammals are not aquatic.

Our lack of body hair aids in persperation, a plus on the rather hot grassy plains where our ancestors evolved. Many mammals in such environs have lost significant amounts of body hair.

2) Unlike our primate cousins we have a subcutaneous fat layer which insulates us in the water and provides us with buoyancy.

Personally, when I jump in the water, I sink and get cold. So it's not particularly effective in either role.

The subcutaneous layer of fat is primarily a "food storage" area for hard times, even in truly aquatic animals. Insulation and buoyancy are at best secondary purposes. Thus, one doesn't need an aquatic theory to explain why we have such a layer.

3) Our extraordinary ability to swim long distances (I’ve been a kayak escort for swimmers circumnavigating Manhattan Island).

We are at best clumsy swimmers, IMO. Bipedalism doesn't lend itself to the most efficient swimming. Many land animals which have no evolutionary link to the water are at least as good swimmers as H. Sapiens. Also note that the hand is better suited for climbing and grasping than swimming.

In addition, I didn't think the "aquatic ape" theory required us to be long-distance swimmers; more like hanging about in the shallows. We aren't talking "Water World" here.

4) The fact that sea food tastes so good and is so good for us implies a long association with the sea.

Does the fact that some birds taste so good and are good for us imply a long association with the air?

Seafood is generally low in fat and high in protein; of course it's good for us. So are nuts. So are eggs. So is fowl. So are legumes. I don't think one can make the leap from that fact that therefore, we had a long association with the sea.

Mageth

lol, pz. Trust me, I didn't read your post before posting mine; it looks like we were thinking much the same on this one.

Baidarka

PZ
See what I mean I feel like I just waved a red flag at a bull.


“ I have a friend who likes rock climbing -- so he should favor an 'alpine ape theory'.”

I don’t know about the alpine ape theory but I would say that this is consistent with the arboreal ape theory which most of us accept.


“Elephants, rhinos, and mole rats are aquatic? Are otters naked?”

Elephants, rhinos, hippos, pigs, spend time a lot of time in water and are excellent swimmers they are semi-aquatic. While mole rats are naked subterraneans whose nakedness has a totally different purpose I don’t think that that anyone has proposed a tunneling ancestry or TAT. Otters are furry water creatures with a very specialized oily water proof fur which traps insulating air close to its body I don’t think that simian fur could have easily been adapted in this way.

“We have a bit more fat, but it's probably more a consequence of neoteny than any functional cause. The fat we do have is completely inappropriate for insulation. For one thing, it's in the wrong place -- having a nice thick belly does no good if you are losing heat from your ankles, elbows, and head. For another, human fat is most definitely not a useful insulator. It's well vascularized, and so is just another region where body heat is rapidly dissipated. Animals with insulating layers have something we don't: vascular countercurrent exchangers to retain blood heat.”

I must disagree with you here. In the swim around Manhattan (28 miles) there are very few skinny swimmers. We have a polar bear club that goes swimming off of Coney Island every winter none of these folks are skinny.
You ignored the buoyancy factor. A nice layer of fat helps to keep a swimmer warm and buoyant. I agree that our hairlessness could be a result of neoteny but unless it was advantageous I doubt if we would have retained it. Short pudgy legs could have been neoteny also but somehow they never became too popular

“I'm trying to imagine what environment would be ruled out by this logic, and how it could be extended. Is there any environment which produces plants and animals that we do not like to eat?”
”I like clams and potatoes, so my ancestors must have been subterranean?”


Yes Clams that’s my point. Clams, oysters, lobsters, muscles, crabs, sea urchins. These are foods which are wonderful raw and stimulate near ecstasy in sea food lovers.

“We might be better at swimming compared to a chimpanzee (although I haven't seen anyone try to train a chimp to swim, so I could be wrong), but we aren't particularly good at it.”

We are an exceptional in the ape family with our ability to swim long distances and our ability to dive deep under the water.

“People swimming around Manhattan are examples of our species' interest in novel and even extreme experiences, like people who sit on flagpoles, go ballooning, or engage in dance marathons. They aren't evidence of ancestry.”

But the ability to do it is not a novelty it is part of our genetic heredity.

“Elaine Morgan has been peddling this stuff for years, and it just gets worse and worse.”

I think that she presented a pretty good case, but I am open to the idea that this is only a theory and I would be just as happy with a well reasoned refutation as I would be with proof that it is correct.

Mageth

Elephants, rhinos, hippos, pigs, spend time a lot of time in water and are excellent swimmers they are semi-aquatic.

Not exactly, except for hippos. Elephants wade in the water and wallow, and on relatively rare occasions have been observed swimming. Rhinos wade and wallow, but I've never heard of one swimming (they may; I've just never heard of it, so if they do it's probably rarely). Pigs only swim if they have to. None of these species, except the hippo, could be described as "semi-aquatic." And none of them swim enough to have lost their hair to become better swimmers (err...many species of wild pigs are typically quite hairy, BTW).

The jaguar is more "aquatic" than any of those creatures except the hippo, BTW, and last I checked, jaguars have a quite nice coat of fur. As are the moose, tiger, and many other hairy mammals.

While mole rats are naked subterraneans whose nakedness has a totally different purpose I don’t think that that anyone has proposed a tunneling ancestry or TAT.

So aquaticism (if there's such a word) is not the only evolutionary reason for a mammal to become "hairless". Doesn't help your point much.

BTW, bonobos are relatively more "hairless" than chimps, gorillas, and orangs, but not so much as us. Even chimps are often bald., and I believe often less "hairy" than gorillas typically are. What does that tell us? Are they or their ancestors semi-semi-aquatic?

Otters are furry water creatures with a very specialized oily water proof fur which traps insulating air close to its body I don’t think that simian fur could have easily been adapted in this way.

There's also the beaver, capybara, platypus, lechwe, nutria, polar bear, sea lions, jaguar, moose, and fur seals, among others.

I must disagree with you here. In the swim around Manhattan (28 miles) there are very few skinny swimmers. We have a polar bear club that goes swimming off of Coney Island every winter none of these folks are skinny.

Volume-to-surface area ratio explains that quite nicely, without having to resort to the "insulating layer of fat".

And the aquatic abilities of a group of 21st century humans is not exactly great evidence, BTW. I'm quite adept at flyfishing, as are several of my friends. I like to wade in swift rivers when I do, and have become skilled at it. Were my ancestors wade fishers, able to tie a duncan loop and make a nice roll cast?

You ignored the buoyancy factor. A nice layer of fat helps to keep a swimmer warm and buoyant.

For some reason, I have a hard time envisioning primitive hunter-gatherers, eking out a living on a seashore, eating protein-rich diets, as having enough body fat to give them much of a buoyancy (or warmth) advantage.

I agree that our hairlessness could be a result of neoteny but unless it was advantageous I doubt if we would have retained it.

Think perspiration advantage. Imagine living on the open savannahs of Africa wearing a fur coat.

Short pudgy legs could have been neoteny also but somehow they never became too popular.

Adult humans have less short and pudgy legs than infant humans. They also typically have a lower percentage of body fat.

Yes Clams that’s my point.

Clams (along with oysters and mussels) can be dug from riverbeds and beaches at low tide quite easily without swimming.

Clams, oysters, lobsters, muscles, crabs, sea urchins. These are foods which are wonderful raw and stimulate near ecstasy in sea food lovers.

And disgust in others, even allergic reactions in many. So what?

We are an exceptional in the ape family with our ability to swim long distances and our ability to dive deep under the water.

So we're the best of the 5 extant species of great apes. We're the best of a sorry lot of swimmers, then. That's not saying much; our aquatic abilities are still marginal at best.

But the ability to do it is not a novelty it is part of our genetic heredity.

That's to be established. We could have picked up our swimming skills on the side, and it could have happened long after we lost our hair, developed our layer of fat, etc.

I think that she presented a pretty good case, but I am open to the idea that this is only a theory and I would be just as happy with a well reasoned refutation as I would be with proof that it is correct.

I wouldn't classify it as a "theory" at all. An hypothesis, perhaps.

At this point, other theories or hypotheses explain H. Sapiens' physiological development better than the aquatic ape hypothesis. The onus is on the proponents to establish it as a superior theory or hypothesis, not on us to disprove it. The proponents of the aquatic ape hypothesis, after, what, 2 or 3 decades, have been unable to demonstrate that it qualifies as a superior hypothesis or theory. Basing a hypothesis on faulty assumptions such as "hairlessness = aquatic lifestyle" is not the way to go, BTW.

Nic Tamzek

Yeah, my dad projectile vomits all night if he accidentally eats seafood. Must be an evolutionary throwback.

I'd almost be willing to bet that more humans die of drowning every year than engage in any kind of long-distance swimming. Speaking as a near drowning victim myself I know just how easy it is for us humans to overestimate our swimming capabilities and rapidly get into a situation from which self-powered escape is well-nigh impossible.

nic

(OK, yes, it was stupid of me to try and swim across a snowmelt-derived river, above a set of small rapids, while wearing my hat, glasses, shirt, and sandals in addition to my swimsuit. But at least I was smart enough to do it just after a raft passed by, right?)

Doubting Didymus

Skirting a bit close to the Darwin awards there, my friend.

Oolon Colluphid

Just to pick a nit here: elephants are actually rather good swimmers. I’d never have believed it till I saw the BBC nature programme on Indian wildlife, 'Land of the Tiger', a few years back, where they had some incredible below-surface footage of elephants crossing a river. Sure, they don’t swim that often, but then they’re terrestrial and don’t often need to; nor is their standard habitat -- savannahs, forests, and jungles (the three species respectively) -- exactly aquatic. But when there is water, they can happily swim in it.

And don’t forget that it seems elephants did have an aquatic stage in their ancestry... and that they are nearest to the Sirenia -- dugongs and manatees -- too.

Eg:

West, J.B. 2001. Snorkel breathing in the elephant explains the unique anatomy of its pleura. Respir Physiol 126 (1): 1-8:
And Gaeth et al’s PNAS article The developing renal, reproductive, and respiratory systems of the African elephant suggest an aquatic ancestry (Vol 96 pp. 5555–5558, May 1999) (pdf).

None of which supports the AAT, and I’m sure elephants are pachyderms rather than trichoderms because of the sun, not water. But I like to get stuff right...

Cheers, DT

VonEvilstein

I must say, I've always been fond of the AAT - it's thought provoking, if nothing else. However, there's a point you may have missed.

Human nostrils, positioned as they are, allow us to swim without the water we're swimming into going strait up our noses. I am not aware of other great apes with their nostrils positioned "downwards".