AAH Evidence

Pat Dooley (patdooley@aol.com)
19 Dec 1994 00:20:44 -0500

This is a response to messages I lost somewhere in the
bowels of AOL. So, the header stuff might in error:

responding to :

umwinkl0@cc.umanitoba.ca (Kevyn Loren Winkless)

<< mucho deletia>>

=fossilization. Or haven't you been following this thread?

I was away from the net from January until now. It seems I haven€t
missed much.

=The fact remains that _modern_ examples of semi-aquatic apes are _not_
=evidence that one of our ancestors was semi-aquatic. It merely points
=out that it is not impossible that this was so.

The AAH, to my mind, is a theory along with all the other theories.
I think it has more going for it than the largely discredited savannah
theory because it uses fewer causes to explain more animalies
than any other theory of early human evolution.

=Without structural evidence (and I have yet to see any which was not
=merely conjecture based on analogy) _there_is_no_way_ to verify or debunk

=the hypothesis. I am still trying to scare up some more literature, so I

=don't know the details of the assertions made by AAT, but if there is no

Try Morgan€s The Scars of Evolution. She provides extensive citations.

=It has been suggested that the only way to support the hypothesis would
=be to discover fossil hominids in an appropriate context - but this has
=been refuted sufficiently, I think, for us to say that while it would be
=suggestive it would not be sufficient in and of itself.
=Are AAT proponents able to suggest:
=a) probable _physical_ evidence to support aquaticness
All the AAH has to go on are the pecularities of modern
humans, Lucy€s bipedalism and small brain, and the principle
of convergent evolution.
=b) a probable region in which such evidence will be found?
=If so, get funding (rob your piggy bank if need be), go there, and look
=for your evidence. If you find it, good. If not, well...
Morgan suggests the Sea of Afar which used to exist in North East
Africa before it dried up about 3 mya.

Who€s going to fund research into a crackpot theory?
=>If an ape goes into the water it is more likely to do it on 2 legs than
=>Of the primates observed doing this in the wild the score is :
=>2 legs: 2; 4 legs: nil.
=>If environmental conditions make an ape do it often enough, it will
=>get better at it. It might take a few million years of evolution to
=>achieve proficiency, but it'll happen, or the ape will go extinct.
=Yes, _but_ it has also been pointed out that these primates go bipedal
=_only_ when they are unable to go further quadripedally without

The footage I saw showed Macaques walking into the water
bipedally. Morgan cites a documentary film (Siarau) showing
proboscis monkeys wading chest deep. A Japanese documentary
€Long nose, Long Tail€ shows a group of these monkey€s
walking bipedally. Monkeys, in general, are less likely to
resort to bipedalism than African apes, but they do do it in

=...if the aquatic ancestor were comparable to these primates,
=why was not quadripedality retained, as it was in the primates you so
=fondly hold up as examples? And if our aquatic ancestor was more
=aquatic, there is still no evidence that this would force bipedalism;

For an arboreal ape unused to water, keeping the head out of the
water for as long as possible would make sense. For a fully
quadrupedal animal with no innate bipedal tendency it wouldn€t
make sense.

Bipedalism, in the human sense, means legs, pelvis and spine
are aligned in the vertical plane. This is the configuration
found in aquatic mammals because it facilitates swimming
and diving. If the AAT added swimming and diving to its
repertoire then we would expect bipedalism to be reinforced.
All we know for certain is that humans, unlike chimps and gorillas,
can swim and dive quite well.

<< deletions>>

=I agree that bipedalism requires huge architectural changes, and as such
=represents a huge investment in specialization...but despite the fact
=that humans have long relied heavily on shellfish and other aquatic food
=sources, there is no evidence that bipedalism evolved specifically for
=aquatic purposes. Plenty of plains-dwelling animals are bipedal:
=groundsquirrels and other rodents for one example, and many birds have
=become bipedal to the extreme to deal with long grasses etc (although
=they were bipedal to start with, and so had presure to retain the
=structure). Wading animals are appropriate analogous evidence for
=pressures toward bipedalism, but savanna/prairie animals are not? You
=see the dangers of speculating on the basis of analogy.

Sorry. Bipedal in the human sense has a specific meaning beyond
the ability to walk on two legs. It means a vertical pelvis, aligned
with the spine and legs. It is also the preferred mode of locomotion.
There aren€t many non-human examples although I vaguely recall
references to penguins.

<< deletions>>

=I agree that the entire question of bipedalism etc. demands further
=study...it is clear that we don't understand everything, and that there
=are huge gaps in our knowledge of our own history which might lead to
=AAT might very well be true, and even if not it might be a useful
=_but_ we need a great deal more substantial information before that will
=be the case. Analogy is fine to flesh out an already well substantiated
=hypothesis, but it is not proof. Give us something more.

The starting point has to be the differences between African apes and
humans. There is a long list that has been endlessly discussed in this
forum. The evidence is circumstantial although some of the geological
and DNA evidence is supportive. Lucy€s bipedalism is negative evidence
for one explanation of bipedalism - that it facilitated carrying and
throwing weapons.

Pat Dooley