Re: Dissecting the Aquatic Ape: Bipedalism
Elaine Morgan (elaine@desco.demon.co.uk)
Sat, 20 Jul 1996 14:00:34 GMT
In article <DurBvx.1sB@inter.NL.net> ghanenbu@inter.nl.net wrote...
ckle-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.
That sounds to me like no, they can't walk with their hands flat
enough to bear weight on them . Good. Glad to have it confirmed.
>
>
> 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?
Well maybe mess is the wrong word, but it would louse up a lot of the
ideas that have been aired. If the l.c.a. was a knuckle-walker that
surely means the l.c.a. was already terrestrial to at least the same
extant as the apes. So all the stuff about why did they come to the
ground could be referred back to 12 or fifteen milliom years ago for
all we would know.
Also it would mean either that l.c.a. was pretty big, big enough so that
the high branches wouldn't support it any longer, or it would have had
some other different reason for coming to ground. Like what? (I know -
"there doesn't have to be a reason...")
>
If it was pretty big, that puts a bomb under the idea that it was
zinging through the branches like a gibbon, and had very very long arms
that it secondarily lost... It seems to me if you postulate a
knuckle-walking l.c.a. you'e letting yourself in for quite a string
of "secondarilies". And that does feel messy.
Elaine
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