Re: An alternative to ST and AAT

Paul Crowley (
Wed, 20 Nov 96 13:02:39 GMT

In article <56sgt5$> "Gerrit Hanenburg" writes:

> (Paul Crowley) wrote:
> >But any serious thought on Lucy's morphology should lead to
> >the same conclusion. If you can't stride, you must waddle.
> You are confusing concepts.

I don't think so. We're into the meanings of ordinary English
words but distinct locomotory differences can be seen and I think
it might be possible to have scientific definitions. "Striding",
as I understand it, is a peculiarly human motion where an easy
rhythm is built up as each leg is swung foward a kind of pendulum
and the body moves in a fairly straight line. The term is also
used in rowing, quite appropriately, for a steady rhythmic stroke
where energy is conserved to cover distance at a fair speed. The
key to this rhythm is that the centre of gravity is kept over the
line of progression. No energy is wasted moving from side to side.

Striding, in this sense, rules out waddling, which as you say,
involves excessive lateral displacement. Chimpanzees and gorillas
cannot stride when they walk bipedally; nor could Lucy or male
A.afarensis. Surely the development of the bipedal stride was
the major change with H.erectus morphology?

> Both Lucy and modern humans have what is called striding bipedalism.
> Striding bipedalism refers to the kind of locomotion in which the body
> is supported by first one leg and then the other,and as the body
> passes over the supporting leg,the other leg swings forward in
> preparation for the next support fase. During transfer of the body
> from the trailing to the leading leg there is a brief period when both
> feet are on the ground.

I cannot see how you would distinguish "striding bipedalism"
from "non-striding bipedalism" under your description.