Re: Initial bipedalism

J. Moore (
Wed, 5 Jul 95 09:51:00 -0500

El> For an ape unadapted to
El> bipedalism, running on two legs (though not apperently walking on two)
El> is much more energetically expensive as well as much slower.

El> Bipedalism is
El> initially so inefficient that the initial stages would only have been
El> embarked on under duress, as by the proboscis monkey.

Your first sentence states correctly that for an ape (specifically, in
this case, a chimpanzee, walking bipedally is *not* more energetically
"expensive" than walking quadrapedally. Your second sentence
contradicts this by saying that bipedalism is "inefficient". Please
reconcile these two contradictory statements for me.

El> The only extant animal model for a wild primate which spends much time
El> in the trees but at ground level often walks on two legs is the
El> proboscis monkey, wading through its mangrove habitat.

Please provide refs for your contention that the proboscis monkey walks
bipedally more often than all other monkeys and apes.

Gibbons, on the other hand, generally walk bipedally when on the ground.

Jim Moore (

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