Re: bipedalism and AAH

loopy (
6 May 1995 20:34:40 GMT

In article <3o6ocr$>, (HARRY R.
ERWIN) wrote:

> I just went through the paper in Ancestors about the elbow and knee
> adaptations of hominids. Bipedalism apparently requires at least a
> moderately rigid knee and can tolerate a lax elbow. Afarensis apparently
> had the rigid knee, plus enough rigidity in the elbow to prevent
> dislocation when climbing. Pan has rigid elbows and lax knees. Has anyone
> studied joint rigidity in semiaquatic animals? Does that provide insight
> into the 'aquatic ape'?

Well, you first need to define "semiaquatic"; which no one seems willing
(or able) to do. Truly "aquatic" mammals have greatly reduced or
nonexistent hindlimbs. But even if you do check knee rigidity in
semiaquatic animals (whatever they are) vs humans, you will probably not
find any useful information. Joint rigidity is easy to achieve and has
happened countless times in the vertebrate lineage. It can't be used as a
diagnostic tool to determine past behavior, especially when present
behavior _necessitates_ that a particular joint be rigid. Rigid knees fit
in just fine with the savannah-ape or forest-ape scenario, and so cannot
support the aquatic ape hypothesis.

Lucie Melahn "You may achieve inner tranquility, but you
Cornell University can't escape surface tension." -V.Louise Roth