Re: Lucy's pelvis
James C. Ohman, Ph.D. (firstname.lastname@example.org)
30 Oct 1995 17:55:47 GMT
Alex Duncan <email@example.com> wrote:
>To my eyes, Lucy's postcrania look more chimp-like than human-like. Her
>humerofemoral index is intermediate between human and chimp.
Therefore, given that the humerus is isometric with body size (e.g.
Jungers, 1994; 1995), Lucy has a relatively LONG femur.
>A. afarensis) has long, curved phalanges on hands and feet.
I will grant you "curved" However, who knows what that REALLY means
since even a dog ahs curved phalanges.
Long relative to what though? They're absolutely very short. And when
placed next to the phalanges of ANY ape, they are clearly, relatively
>phalanges have pronounced ridges for the "flexor sheaths."
Pronounced relative to what? And what does this mean? Gorillas have big
ones that relate to knuckle-walking. Does this mean Lucy knuckle-walked?
I think not.
>glenoid is cranially oriented (vs. laterally oriented in humans),
>indicating arms were used frequently in overhead positions.
Could just as easily be allometric. Small humans have a more cranial
orientation too (see Mensforth, et al. 1990)
>reconstruction indicates a conical, rather than "barrel shaped" thorax.
So what? Gibbions have a barrel shaped thorax and I'd call them
arboreal. Thorax shape has nothing to do with locomotor habitus (contra
>As far as the pelvis goes, when viewed anteriorly it does seem more
>human-like, as it is craniocaudally shortened and mediolaterally
>exapanded. However, when viewed cranially, the iliac blades are
>conspicuous in their dorsal orientation. In other words, the bone
>surface for attachment of the gluteal musculature faces dorsally, rather
>than laterally as is the case in humans. In this aspect particularly,
>Lucy's pelvis resembles that of a chimp. Since the gluteal muscles are
>among the primary muscles involved in extension and abduction at the hip,
>and these are among the most important locomotor movements that occur at
>the hip, it is not unreasonable to say that in biomechanical terms,
>Lucy's pelvis is still very chimp-like.
You are basing this entirely on Stern, et al.'s early drawing of the
unreconstructed pelvis, and probably also Schmid's faulty reconstruction.
Look at Tague and Lovejoy (1986). Or for pete's sake, look at a cast of
the thing next to ape and human pelvises. If you still believe this then
you are simply blind (no, worse, because you can easily palpate the
James C. Ohman, Ph.D.
The Johns Hopkins University School of Medicine.