Re: AAT Theory

Alex Duncan (
23 Oct 1995 12:18:49 GMT

In article <> Elaine Morgan, writes:

>> Yes, it is, after five million years of practising it and perfecting
>it. What we need to ask is why one sector of the last common ancestor
>*began* practising it when it was still very inefficient as a means of

What do you have to support your contention that the early stages of
bipedalism were very inefficient.

Most folks who've tried to work out models for australopithecine
bipedalism have come with a model in which aust. habitual bipedalism
bears some resemblance to the facultative bipedalism of chimps (i.e.,
hips and knees not fully extended at any point during the stride cycle).

The data that Rodman & McHenry cite indicate that chimp bipedalism and
chimp quadrupedalism are about equally energetically efficient. This
suggests to me that australopith bipedalism was no less efficient than
chimp quadrupedalism (or chimp bipedalism).

Alex Duncan
Dept. of Anthropology
University of Texas at Austin
Austin, TX 78712-1086