Re: Lucy's pelvis
Alex Duncan (aduncan@mail.utexas.edu)
1 Nov 1995 13:43:54 GMT
In article <4733j3$cgv@news.jhu.edu> James C. Ohman,
johman@welchlink.welch.jhu.edu writes:
>>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.
We've already had this discussion. Yes, lucy had a relatively long femur
relative to apes. It was relatively short compared to humans.
>>She (well,
>>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
>short.
Latimer & Lovejoy demonstrate overlap in proximal pedal phalanx length in
A. afarensis and African hominoids (some phalanges, and some hominoids --
I'll have to dig up the paper to be sure).
>>The manual
>>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.
Pronounced relative to humans. No, I don't think it means Lucy
knuckle-walked. What it probably means is that A. afarensis had a very
powerful phalangeal flexor mechanism. Obviously, we can debate all day
about what that means. I think it means A. afarensis hands were used to
grasp branches in arboreal positional behaviors.
>>The scapular
>>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)
I was unaware. I'll check it out. (Is it in AJPA?)
>>Thoracic
>>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
>Hunt).
I wasn't trying to point out any connection to locomotor behavior. The
original poster apparently had some difficulty seeing difference between
the postcranial skeletons of Lucy and WT 15000. I was pointing one out
for him.
What problems do you see w/ Hunt's analysis? (Please respond by e-mail
if you don't want it on the net.)
>>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
>differences)
I am not basing this entirely on Stern et al.'s drawing. I have casts of
the relevant pelvic remains. I also have casts (right and left sides) of
Sts 14, and I see the same thing there. Obviously, on a gross anatomical
level, australopithecine coxae resemble those of humans. However, in
some of the details they retain chimp-like features. Frankly, even in
Tague & Lovejoy's reconstruction, it appears to me that the gluteal
surface faces largely dorsally.
BTW -- I don't have any real stake in the matter, but what's faulty about
Schmid's reconstruction?
Alex Duncan
Dept. of Anthropology
University of Texas at Austin
Austin, TX 78712-1086
512-471-4206
aduncan@mail.utexas.edu
|