Re: AAT Theory

Troy Kelley (
Tue, 31 Oct 1995 18:02:59 GMT

Subject: Re: AAT Theory
From: Gerrit Hanenburg,
Date: Sun, 29 Oct 1995 13:11:04 GMT
In article <> Gerrit Hanenburg, writes:
> (H. M. Hubey) wrote:
>>OF course, human biped motion is not too efficient.
>That depends on the speed:
>"At maximum running speed human bipedalism is twice as expensive
>energetically as estimated for a quadrupedal mammal of the same body
>"However,at average walking speed (4.5 km h^-1) human bipedalism is
>slightly more efficient than is quadrupedalism in the average mammal.."
>From:Aiello and Dean._An Introduction to Human Evolutionary Anatomy_
> Academic Press 1990,p.272.

It seems to me that running speed would be the most improtant variable if
you were evolving in a savanna type environment.

The fact that humans have such a slow running speed coupled with the
fact that it is very expensive in terms of energy coupled with the fact
that the savanna is typically a very hot environment makes one wonder why
bipedalism would have evolved at all. I am sorry, but I don't accept the
traditional, pat answer of cooling the body through reduced exposure to
the sun. There are plenty ways to get cool besides "going bipedial", and
no other animals show this tendanancy.

Again, I would like to see other people post ideas as to why bipedalism
evolved instead of the AATers continually having to defend their
positions. I posted this request once before and I was simply told to go
read the literature, which was essentually a brush off. If you have a
good theory to bipealism, please post it.