Re: escaping preds in H2O

Alex Duncan (
28 Sep 1995 02:28:34 GMT

In article <449ar3$> ,

>2. The argument that hominid hindlimbs "were about the same length
>relative to body a size as is the case in modern chimps" is outdated. It
>is largely based on the earlier work of Jungers. Many have disagreed
>over the years (e.g. Wolpoff). Nonetheless, even Jungers can no longer
>support this view. Jungers has changed his views and now argues that the
>forelimb is isometric among humans and African apes - as well as Lucy
>(Nature 369:194; AJPA Supplement 20:193). Therefore, because the
>humeral/femoral ratio of LUCY is about 84, the length of her femur must
>be relatively longer than that of a chimp. In other words, if humans,
>chimps and Lucy all have the same length humerus (relative to body size)
>AND the humeral/femoral ratios differ between these groups, THEN femoral
>lengths, relative to body size, MUST differ between these groups.
>Relative to chimps, Lucy's femur is long.

You got me. I should have thought this through a little more before I
posted. However, I don't think the basic point changes. Yes, Lucy's
femur was relatively long compared to that of a chimp. But it was
relatively short compared to that of a human. We all know the kinds of
problems that are apparent in trying to reconstruct these things. For
example: what if Lucy only weighed 25 kg? -- then she has quite long
femora relative to body size. But what if she weighed 32 kg? --
obviously her femora will then be a little shorter relative to body size.
The same arguments will have an impact on the interpretation of her
relative humeral length as well.

The basic point doesn't change, however. That is: early hominid femora
were short relative to body size (compared to modern humans), and
remained that way for about 2 Myr, if not longer (see, for example, OH
62). This is hardly the kind of thing you'd expect if there was constant
selection for longer length to facilitate more effective WADING.

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