Re: AAT Theory

Thomas Clarke (
9 Oct 1995 13:01:51 GMT

In article <453pge$> chris brochu
<> writes:
> In article <453n59$> Thomas Clarke,
> writes:

> >for the AAT. You concentrate on the failed aquatic characteristics and
> >reject the theory. Well fossils will tell eventually.

> >If I apply the same viewpoint to the "land theory", one would expect
> >a hominid to display characteristics of other savannah dwelling
> >animals. As near as I can tell, hominds are unique among savannah
> >animals. Hence, to me, the "land theory" is disproven.

> Sounds like you completely missed my point. I reject AAS not only
> because there is no evidence for it, but because the scenario proposed by
> primate phylogeny requires nothing like it.

I guess I did miss your point. Now I don't understand you at all,
however. What do you mean by "scenario"?
The facts are a few fossils and present day animals. There are
no "scenarios" in nature. The phylogeny inferred from the fossils
and (now) DNA evidence is an hypothesis.
I for one, find the totally land-locked version of the hypothesis

> Furthermore, I never said we became bipedal on the savannah. I suggested
> something more like a forested environment.

OK. Make use of any land environments that you choose, but stay
away from water as is your wont. Convince me, however, that the
transition to bipedalism can happen on the land.
Something along the order of detail of Paul Crowley's
"Becoming altricial/bipedal" post is needed.

> For a good model, take a look at macropodids. The earliest relatives of
> bettongs, wallabies, and kangaroos were forest animals that became
> bipedal, probably to jump over obstacles. When the forests went away,
> they stayed bipedal. (And no, before you flame, I'm not proposing a
> saltatorial phase in our evolution. Only pointing out that we aren't the
> only bipedal open-ground creatures, and that the evolution of bipedality
> in macropodids might be a worthwhile analogy.)

You almost make my point. Are there not several species of macropopids?
The environment favored the development of bipedal jumping (saltation)
and several species "answered the call" by becoming macropopids.
If the general forest/savannah paleo-environment of Africa favored
bipedalism, then where are the other bipedal animals?

Tom Clarke