Re: Bipedalism and other factors

Alex Duncan (
27 Jun 1995 19:21:36 GMT

In article <> Nicholas Rosen, writes:
>What I think Pat meant is that there is no sign of sexual dimorphism
>in bipedalism. Males were neither more nor less bipedal than females
>of the same species.

Are you sure about that? It may seem unlikely that males and females
would have different regimes of positional behaviors, but we do see such
things in modern gorillas and orangs. In both of these taxa, females are
more frequent arborealists than males.
See Stern & Susman (1983) Am. J. Phys. Anthrop. and Susman et al.
(1984) Folia Primatologia for a discussion of sexual dimorphism in
locomotor anatomy in A. afarensis. They suggest a greater frequency of
terrestrialism in males.
But really -- what do sexual differences in locomotion have to do
with display. I've never seen any hints that male and female chimps
differ significantly in locomotor behavior, but males display routinely
and more frequently than females.

>Leopards may normally hunt FROM trees, but if a
>creature on the leopard diet climbs a tree, will the leopard decline
>the opportunity to eat it because that isn't the way a leopard
>usually hunts?

I challenge you to find a single known instance of a leopard catching a
healthy baboon or chimpanzee IN A TREE. I'm not saying that it doesn't
happen, but it probably happens so rarely as to be insignificant.
Primates are much more adept in the arboreal substrate than leopards are.
Leopards are generally confined to the trunk and large proximal
branches. Primates (especially suspensory hominoids) are capable of
movement in the smaller distal branches where quadrupeds can't go.

A secondary and important point -- are we suggesting that primates
shouldn't climb trees because there are leopards there? This is getting
really ridiculous. You can count the number of terrestrial primate
species in Africa on the fingers of both hands. There are at least 50
species of primate in Africa (where the leopards are) that are almost
exclusively arboreal.

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