Re: Dissecting the Aquatic Ape: Bipedalism

Gerrit Hanenburg (
Thu, 18 Jul 1996 21:03:33 GMT

Elaine Morgan <> wrote:

>In article <> wrote...

(list of knuckle-walking features snipped)

>This is a very useful list. Can you settle the query of whether
>or not gorillas and/or chimps can flatten the palm and extend the
>elbow at the same time? I have seen it positively stated that
>they cannot.

The knuckle-walking apes have a limited degree of dorsiflexion of the
hand because,as I already mentioned in the list,the distal articular
surface of the radius is deeply concave and because it has a
pronounced ridge on the dorsal rim which,during dorsiflexion,abuts
against a well-developed ridge on the scaphoid (a carpal
bone),limiting futher extension and making it impossible to dorsiflex
the hand to an angle of 90 deg. in relation to the forearm.

>>On the basis of the above mentioned skeletal features associated with
>>knuckle-walking we can at least make the testable prediction that if
>>the LCA was a knuckle-walker,fossils of it will show these features.

>And if it was that would make a bit of a mess of the cladistics,
>wouldn't it?

It would mean that knuckle-walking is the prmitive state,which has
been retained by chimpanzees,and was secondarily lost by the hominids.
What would be the cladistic mess?