Re: First Family and AAT

Thomas Clarke (
14 Oct 1995 13:20:58 GMT

In article <> writes:
> TC> >early aquatic hominid have been any different? In other words, if
> TC> >becoming a biped is such a wonderful adaptation to an aquatic
> TC> >existence,
> TC> >why aren't polar bears, walruses, alligators, mososaurs and otters all
> TC> >bipedal?

> TC> I will try a rhetorical device to show the vacuousness of this argument.

> TC> To the best of anyone's knowledge, every tetrapod that ever transitioned
> TC> from an arboreal to a terrestrial environment ultimately became a
> TC> quadruped. Why would the early proto-hominid have been any different?
> TC> In other words why aren't chimpanzees and gorillas bipedal?
> TC> Tom Clarke

> You've missed the irony in Alex's question. You see, it's a
> standard question among AATers, Morgan included, to continually
> ask things like "if it was useful for hominids to be bipedal, why
> aren't all non-forest primates bipedal?" Alex simply was
> turning it around for effect and asking it of the AATers. I've
> done this, as have others, because when we try to explain that
> evolution doesn't work that way, we're ignored.

I guess I did miss the irony. The problem is that you haven't truly
reversed the AAT argument. I would agree that any group of apes isolated
on a warm shoreline/littoral environemnt where part of the food would come
from the sea would become bipedal. But the precursors of seals and
dugongs and whales are not apes. There is only one example
of full-bipedalism aquired in this way, but several monkeys seem
started in this direction.

> So since AATers apparently believe that a terrestrial transition
> for humans means that many many open-country mammals should be
> predominately bipedal, and that the fact that they aren't is a
> grevious blow to all of paleoanthropolical theory, why shouldn't
> they answer the question of why aquatic mammals aren't
> predominately bipedal?

Becasue there are several examples of apes that have evolved beyond the
miocene tree dwelers in a land environment. Of those four (3?),
one one has become bipedal.

In short the question is about the evolution of apes, not about
quadrapedal pre-seals etc.

Tom Clarke