grasping feet

Alex Duncan (
13 Oct 1995 12:48:29 GMT

In article <45jk3s$> James C. Ohman, writes:

>>>Since fossil foot bones >3.5 mya are extremely rare, and of most
>>>uncertain interpretation, this is pious hope. It's not science.
>>ALL of the fossil foot bones from 3.5 Myr are consistent w/ the view that
>>early hominids retained pedal grasping abilities. What is unscientific
>>about assuming hominids w/ grasping feet used those feet for grasping?
>Patently false. Please refer to Latimer and Lovejoy (1990, AJPA
>82:125-134). This work has never been refuted. And your unpublished
>work that you mentioned in an earlier post does not count since it has
>never been peer-reviewed. Therefore Australopithecus afarensis must be
>viewed as NOT possessing a grasping foot.

To which unpublished work are you referring?

I'm sure you are aware of the different perspectives on the grasping
capabilities of the A. afarensis foot. There are several important
aspects to the anatomy that indicate substantial grasping capacity.

1) Relatively long pedal phalanges. Latimer & Lovejoy question the
conclusions of Stern & Susman on this point, but Latimer & Lovejoy's own
data indicate pedal phalangeal length intermediate between African apes
and humans.

2) Strongly curved pedal phalanges. The work of Stern & Susman and
Susman et al. on this issue has never been refuted.

3) Enhanced capacity for plantarflexion (compared to humans) at the
metatarsophalangeal joint. Latimer & Lovejoy's interpretation of this
aspect of australopithecine anatomy WAS REFUTED.

4) Frankly, I simply don't buy Latimer & Lovejoy's take on the
entocuneiform. The initial impression of it was that the distal
articular surface was "markedly convex" (from the 1982 AJPA devoted to A.
afarensis). I don't want to discuss potential problems w/ Latimer &
Lovejoy's later work in this newsgroup. I do have casts of the AL 333
pedal skeleton, and it is obvious from the casts that the distal
articular surface is convex. It simply does not resemble the same bone
in humans. The proximal articular surface of the metatarsal is concave.
To me, that says "grasping hallux." I also would point out that simply
because Latimer & Lovejoy's work on the hallucal tarsometatarsal joint
has not YET been refuted does not mean that it won't be.

>Clarke and Tobias (1995, Science 269:529-541) claim "grasping" ability
>for the hallux in Stw 573. The did NOT, however, directly compare these
>specimens to either the work of Latimer and Lovejoy, nor even the
>specimens from Hadar. The have also not yet made Stw 573, nor even casts
>of Stw 573, available for comparison. Therefore, the jury remains out on
>Stw 573. However, the the small amount of divergence pictured in Clarke
>and Tobias' figure is clearly NOT ape-like, and they conveniently did NOT
>illustrate an ape in this figure.

I agree that we all need to see casts, etc. My initial impression from
the pictures is that it sure looks like a abductable hallux. I guess we
all have our biases.

Alex Duncan
Dept. of Anthropology
University of Texas at Austin
Austin, TX 78712-1086