Re: An alternative to ST and AAT

Gerrit Hanenburg (
Sat, 07 Dec 1996 08:12:49 GMT (Paul Crowley) wrote:

>I was primarily talking about the switch-over from
>quadrupedalism to bipedalism - over 1 Myr before Lucy.
>She would have been quite advanced by comparison with the
>first hominids, whose bipedalism must necessarily have been
>less effective at ordinary progression than chimps'

Rodman and McHenry (1980 p.105),on the basis of experimental data,
state that "..for chimpanzees,the costs of quadrupedal and bipedal
travel are the same."
There is no reason why we should expect it to be different in an early
hominid with similar body proportions.

>> Nowhere in the literature is it stated that Lucy's bipedalism was less
>> efficient than chimpanzee quadrupedalism.

>This is hardly surprising. "Efficiency", whatever it means,
>can only be measured on some ghastly machine like a treadmill,
>and Lucy is not available.

A reasonable estimate of efficiency can be made from the anatomy,using
biomechanical principles. As a biped, Lucy was very likely more
efficient energetically than quadrupedal or bipedal chimps.

>A better word might be "effective". Of course, "effectiveness" depends on
>the habitat; but if it was open woodland, then the chimp
>would win nearly every time.

And how have you figured that out? By repeated simulation?

>All I'm saying is that she must not have done a lot of
>walking. She wasn't designed for it. So what was she
>designed for?

Sure she was designed for walking. If you deny *that* then you only
show a bad understanding of functional morphology.The changes in her
pelvis and lower limb can hardly be explained otherwise. But
terrestrial bipedalism was not the only component of her locomotor
repertoire and the result is a compromise morphology.

Rodman.P.S.and McHenry,H.M.(1980), Bioenergetics and the Origin of
Hominid Bipedalism. Am.J.Phys.Anth.52:103-106.