Re: AAT Theory

chris brochu (
17 Sep 1995 20:01:00 GMT

This is positively my last post on this subject. I have more important
and relevant issues to worry about.

I strongly recommend that some people involved in this discussion read a
primer on phylogenetic systematics, such as Wiley et al.'s "The Compleat
Cladist." It is clear that many of you honestly don't understand
phylogenetics and should learn more. My "hypothesis 1" doesn't "explain
nothing" insofar as a cladogram is a hypothesis. Parsimoniously, we
cannot posit a step not revealed by primate relationships. (And I do
know the difference between Hominidae and Primates - one is nested within
the other.) It simply explains that the immediate ancestors of bipedal
terrestrial primates were functionally bipedal arboreal/terrestrial
primates, with no aquatic stage in between. I have seen no credible
evidence for such a stage.

(Another kind of "evidence" discussed on the subject - the "diving
reflex." If you refer to the fact that we dive by bending our abdomen,
that's because we're mammals. All mammals swim that way, along with limb
thrashing, because we've largely decoupled the tail and epaxial
musculature from locomotion and breathing. I'll bet if you threw a
gibbon in the water, it would do the same thing. Archosaurs - birds and
crocodylians - show a similar decoupling during their phylogeny. Crocs
keep their bodies stiff in the water while sculling with their tails, and
birds use their feet or wings only. All other tetrapods swim with
lateral undulations, like fishes.)

If AAH proponents are going to advance their idea, financially or
otherwise, they're going to have to start convincing those outside their
field. If I'm any indication, they're doing a lousy job.