Re: AAT Theory

Tom Clarke (
5 Oct 1995 13:04:21 -0400

David Froehlich <> writes:

>Just because there is no monolithic theory about how this
>terrestrial change occured does not mean that AAS is a viable

Doesn't mean it's not either.

>The only reason that it is still an issue on this list is
>that there are a few adherents who refuse to let it die.

It takes two to tango.

> Have you ever
>noticed that most of the pro AAS folks are not professional physical
>anthropologists? This is not because these pro AAS folks are a repressed
>minority. It is because most professional physical anthrologists have
>better things to do.

>From your tone I would say you are a (self styled?) professional.
I am an admitted amateur.
My fascination with this debate stems as much from the reaction
of the professionals as with the technical content.
There is a group (the professionals?) who is positively aquaphobic;
bipedalism happened on the land, only the land and just the land.
When it comes to the AAT's chief proponent in print, Elain Morgan,
they are positively hydrophobic.

I find this most interesting. I personnally had to abandon a
theory I liked in the 60's. There were two competing cosmologies
then the big bang and the steady state. I liked the steady state,
it had a certain aesthetic appeal (As it was in the beginning, it is
now and every shall be, world without end ...). Then Penzias and
Wilson discovered the cosmic background radiation and steady state
no longer fit the observations. I found it sad, but now I will
defend the big bang against any "crackpot". Conceivably something
could overturn the big bang, but I have difficulty imagining what.
[Ironically, one problem with the big bang, the smoothness of the
background radiation, has a proposed solution in an "inflationary era"
in the first microsecond or so of the universe and the equations of
the inflation are, at a vastly different time scale, the equations of
the steady state universe]

For now, I find the AAT scenario "charming". A stretch of time
in a seashore/island environment leading to bipedalism and probably
loss of hair and other soft tissue changes. Ironically, this
preadapted the hominids for life in the relatively dry savannah -
and eventually everywhere else. Of course a couple of fossils
of the right nature in the right location could kill the scenario dead.
Until then I see little to choose between land and littoral scenarios
since there is so little data. It is a matter of choice. If anything
I think the advantage is to the water side. Wasn't Lucy's bipedalism
a bit of a suprise? Had you asked an AATer prior to Lucy what mode
of locomotion a 4 MYA hominid land fossil would use, they answer
would have been a confident "bipedal".

For now, if you want to stop the debate on s.a.p - do you really want
to do that? - all you have to do is say something to the effect:

"The AAT? Oh that's one possible scenario for the development of
bipedalism. There's not much evidence for it one way or the other.
I personally don't think it has much chance of surviving."

>As a final comment, to make AAS a viable scientific arguement it must
>provide a testable series of propositions that are not equally or better
>explained by pre existing ideas.

Well the "better" is a value judgement is the problem in this debate.
The AAT predicts that fossils older than the oldest currently
found, 4.5 MYA, fossils in the "gap", will be found in an
aquatic or shore setting. If pressed I might speculate that
changes in femur length would precede other skeletal changes because
this should be a simple change geneticaly and it would have
practical benefit to a proto-homind wading in the shallows to gather
food. Longer legs -> wading to deeper water. Since the water
supports the weight, other skeletal changes can lag behind.

> A scientific
>speculation or hypothesis must be more than just sexy.

Yes indeed. But sexy works good sometimes. There's an article
by Eugene Wigner "On the Unnatural Success of Mathematics in the Sciences"
where he points out that the way math works well in physics is a
mystery. Math is done because it is neat, or sexy. Then years
later it turns out to be useful in physics. Most mysterious.

>Flame away.

Tom Clarke

People of the same trade seldom meet together, even for merriment
and diversion, but the conversation ends in a conspiracy against
the public, or in some contrivance to raise prices - Adam Smith, WofN