Re: tree-climbing hominids

H. M. Hubey (
9 Oct 1995 21:05:39 -0400

Paul Crowley <> writes:

>I should have dealt with this last time. We are concerned with two forms
>of locomotion: quadrupedal and bipedal. There is effectively no half-way
>stage. (Obviously there must have been a transition, but it must have
>taken place under very special circumstances - which is why the AAT

Why does this have to be true. Suppose we plot x-pedalism along
the abcissa and various measures of efficiency along the ordinate
such as speed, carrying capability, efficiency or some combination
thereof. If by 'no half-way stage' you mean that any one of the
plots would have a dip in the middle (say zero quadped and 1 for
biped) then all the talk revolves around this concept. If there
is agreement that this dip exists in the middle then there must
have been some kind of a lifestyle in which these disadvantages
did not exist or were at least offset. That makes the AAT
attractive since it's exactly these weaknesses that the aquatic
lifestyle would tend to nullify.


Regards, Mark