Harry Erwin (email@example.com)
Tue, 20 Jun 1995 19:44:48 -0400
In article <firstname.lastname@example.org>, email@example.com (Erin
> In article <firstname.lastname@example.org>,
> Harry Erwin <email@example.com> wrote:
> >I went through Tuttle's article on the subject in Primate Functional
> >Morphology and Evolution. Very interesting! Orangs knucklewalk in addition
> >to fist walking when they spend time on the ground. It's not as optimized
> >as in Pan and Gorilla, where the hand has been modified to handle the
> >stresses. On the other hand, I understand the small apes tend to be
> >bipedal, since they don't need the forelimb support as much. Morphology
> >tracks behavior, but at a distance! All this tells us that early hominids
> >probably used knucklewalking at times (when forelimb support was needed)
> >and abandoned it under some sort of selective pressure.
BTW, I suspect the selective pressure was based on life in an open gallery
forest/treed savanna environment that rewarded long-range sighting of
high-grade food resources and predators.
> Look at the morphology, tho. The great apes' torsos are such that their
> center of gravity (balance?) is up in their rib cages, causing the body
> weight to fall forward, hence knuckle/fist walking, or any quadrpedal
> movement, on the ground is logical. But both gibbons and humans have a
> lower center of gravity, so their upper bodies would not naturally fall
> forward. Thru electromyography, gibbons have been shown to expend LESS
> energy walking bipedally than even when brachiating (i'll have to get the
> cite later, sorry). When hominids first came to the ground, they were
> probably gibbon-like in size and torso anatomy, so I'd be surprised if
> they knuckle-walked any more so than the gibbon does, which it doesn't.
But the evidence seems to be that the earliest hominids were on the order
of 20-30 kg (female) and 30-40 kg (male). Now granted those figures are
below the chimps (30-40/40-50), orangs (40/80) and gorillas (80/160), but
they are above the gibbons (10/10). Are they in the bipedal range? I
suspect so, particularly if the very earliest hominids were more like
(10-20/20-30). What's the take of the audience on this?
Home Page: http://osf1.gmu.edu/~herwin (try again if necessary)
PhD student in comp neurosci: "Glitches happen" & "Meaning is emotional"