EVOLUTION: The Aquatic Ape

John K Clark (johnkc@well.com)
Thu, 16 Jan 1997 20:58:14 -0800 (PST)


On Mon 13 Jan 1997 Guru George <gurugeorge@sugarland.idiscover.co.uk> Wrote:

>Everyone should read about the Aquatic Ape hypothesis, as
>championed by Elaine Morgan [...] and was encouraged to note
>that no less a mind that Daniel C. Dennett thinks it's pretty
>reasonable too.

Dennett says "I for one would love to see it vindicated. That does not make
it true, of course". Evolution is more like History than Mathematics,
and there are many very reasonable things in History that never happened.

The diving reflex of infants, and the subcutaneous layer of fat humans have
that is similar to that found in some aquatic animals is the best evidence
for the Aquatic Ape Theory, but I don't think that's enough to prove it and I
have a lot of problems with the other "evidence".

I doubt if our lack of hair has anything to do with living in the water.
Beavers, otters and seals are far more aquatic than we are and they have far
more hair too. I think there is another reason we're bald, we invented cloths.
Humans are much better at getting rid of waste heat than any other large
animal, and that's because we have sweat glands on every part of our skin,
and that's because we don't have a permanent coat of hair. One of our first
inventions must have been the coat, when it's cold we put it on, when it gets
hot we take it off, other animals can't do that, they must ware their coat,
hot or cold, all the time.

One of the greatest mysteries in Human evolution is why we walk on two legs.
Despite claims to the contrary I don't think The Aquatic Ape Theory sheds
much light on this question.

Being a biped is no advantage in swimming, many mammals are much better at it
than we are and they never came close to developing bipedalism. It is not at
all obvious that living on the shoreline must encourage the development of
longer legs. Yes, some wading birds have long legs, but the hippopotamus is
aquatic and it has short stumpy legs, and dolphins and whales have no legs at
all. Actually I can't think of any aquatic mammals that have long legs, much
less find one that is bipedal.

Well OK, It might be a slight advantage in wading, but not much. It's very
difficult to walk in water over a foot deep for any distance, almost
impossible if it's over 2 feet deep, especially if you're only a little over
4 feet tall, as an early ancestor like Lucy was. Why a slight advantage in
wading is more important than running swiftly on land, or even swimming,
the theory does not make clear.

We known for sure that bipedalism developed about 3 and a half million years
ago, the question is why. We are not lacking in theories, there are a
thousand theories to explain why bipedalism evolved, and that's the problem,
we don't need a thousand theories we just need one, the correct one.

John K Clark johnkc@well.com

Version: 2.6.i