Re: An alternative to ST and AAT

Paul Crowley (
Sun, 01 Dec 96 15:40:52 GMT

In article <> "Phillip Bigelow" writes:

> Paul Crowley wrote:
> > It is clear from their anatomy that there was no great
> > selective pressure on the Australopithecines to develop an
> > efficient walking technique,
> "Efficient" can mean many things. "Ecologically-efficient", for
> instance, is much different in meaning than the term
> "biomechanically-efficient". Just because it looks awkward doesn't
> mean that it doesn't convey optimal efficiency for that particular
> animal.

We know nothing of the ecology of the Australopithecines; so
whenever we try to talk about the efficiency or effectiveness
of their bipedalism, we can only do so in the biomechanical
sense. I am sure that Roh, Frankie and Tom meant it in this
sense. I certainly did.

> The only conclusion that can be drawn for most of the 2 m.y. reign
> of Australo's is that australopithicene-style locomotion was
> highly desirable.

This is tautological. We have to try to reach better
conclusions, if only tentatively, such as: (a) they did
not achieve a biomechanically efficient form of bipedalism
because it was not important to them; (b) so they probably
did not walk much; (c) so they stayed in the much the same
place, i.e. they had static sites; (d) running was not
important; (e) so no hunting, little scavenging, few
predators, and a fairly safe supply of food in protected
locations; (f) they lived in rough mountainous territory
where a striding gait would not have been as useful as
on open plain or on flat ground.

An efficient striding gait is desirable if the species
does any walking at all; so we also need to identify the
causes inhibiting progress towards it for some 2 Myr. My
current hypothesis is that, while they spent much of their
time on the littoral slowly foraging for shellfish, they
also needed to climb pole-like trees, such as palm trees or
those in a tropical rain forest for which they developed
the flared iliac bones for the attachment of powerful
gluteus muscles.