Re: Dissecting the Aquatic Ape: Bipedalism

Paul Crowley (
Fri, 26 Jul 96 00:30:26 GMT

In article <4t0ljo$> "HARRY R. ERWIN" writes:

> Paul Crowley ( wrote:
> : In article <4scc02$>
> : "Promethius" writes:
> : > Knuckle walking is an very specialized form of locomotor adaptation,
> : > every bit as much so as bipedialism.
> : This is a wild over-statement. Knuckle-walking is a form of quadru-
> : pedalism, the almost universal mode of locomotion for terrestrial
> : mammals.
> He's actually correct. Knuckle-walking involves walking on the ->backs of
> the hands<-. It's only seen in Pan, Gorilla, Pongo (as fist-walking) and
> some chalicotheres.

Knuckle-walking may be unusual; that does not mean it's "very
specialized". A Ford Edsel may be unusual without being
specialized; a refrigerated truck may be specialized without
being unusual. The number of morphological and behavioural
changes necessary to convert a quadrupedal palm-walker (such as
a baboon, or a monkey) into a knuckle-walker are far less than the
number it would need to become a biped. A palm-walker could well
occupy the same niche as a knuckle-walker (chimps are not *that*
different from baboons). OTOH no one has begun to outline the
niche occupied by the bipedal hominid.

> The original reason for any large ape to move down to the ground is to
> get out of the tree it's in and move to another tree.

Is this true? You're assuming that (large?) apes originally were
100% arboreal - like gibbons. Why? I can see no reason why a
substantially ground-based existence, especially for a larger
animal, should be ruled out. Many primates (e.g. baboons) are
mainly ground-based today. Why should the general pattern have
been different at any time during the past 65 Myr? The ancestral
ape certainly acquired a brachiating capability but that does not
mean that that was its main activity.

> : 2. Likewise we share many behavioural features with chimps, such
> : as: multi-male groups, female exogamy, tool-use, weapon use, sophis-
> : ticated social abilities, war-like tendencies among males, and strong
> : family ties primarily based around older females. If {a} were true,
> : all these would have had to evolve independently at least twice.
> These have not been ruled out as ancestral. These are mostly behavioral
> and hence very labial.

I strongly disagree with you that behavioural features are labile.
They are always intimately tied into niche, and IMHO in evolution
niche is everything.