Re: AAT Questions...

pete (VINCENT@REG.TRIUMF.CA)
20 Jul 1995 20:20:42 GMT

Ralph L Holloway (rlh2@columbia.edu) sez:
`On 20 Jul 1995, pete wrote:

`> Thus, my conclusion is, the more modern the structure
`> of the Ramidus skeleton, the less the aquatic hypothesis
`> is discounted.
`Should we take this to mean that only limb lengths are going to tell us
`whether the structures are for aqautic or bipedal or arboreal locomotor
`adaptations? "More modern" does mean closer to human, doesn't it? I'm
`afraid I didn't understand your post, and I sure don't understand this
`conclusion. Can you try again? Ralph Holloway.

OK, lets see if I can tidy up my thoughts a little: by more modern,
I mean the ratio of fore to hind limbs closer to modern humans, and
feet as a platform, rather than another pair of grasping hands.

If the aquatic theory suggests that our limb structure results from
an aquatic period, then there is not going to be some other limb
structure that it postulates for that period. Therefore the only
thing we can say about creatures towards the end of that period is
that the aquatic creatures must necessarily have already abandoned
all the arboreal traits we find missing from later hominids, but a
simply post-arboreal creature is under no such constraint. How far
along its bipedalism is will depend on how long it's been out of
the trees. Thus I would say that significant amounts of retained
arborealism would count against the aquatic theory, but if they
aren't present, it won't really tell us anything one way or the
other.

Again, I want to point out that I have no expertise in this area,
I was just trying to initiate speculation, my point being that
you don't have to support the aquatic theory to consider what it
might imply. There may, for example, be all sorts of small adjustments
which need to be made to various parts of the anatomy to make
an arboreal ape `seaworthy', of which I have no knowledge, but
which others more familiar with primate anatomy might be able
to pinpoint. I can only consider things obvious to the layman,
and to me, the gross movements used in brachiation would differ
little from those in swimming, except for those instances which
I have noted.

I do not agree, however, with Jim Moore, who says that if there
are no predictions about skeletal anatomy which can be made,
the theory is `intellectually empty'. If there is a chance that
this is really an episode in hominid evolution, then it is not
an empty speculation. It just awaits more subtle and clever methods
of revealing the past.

--

==========================================================================

    vincent@triumf.ca   <== faster       %    Pete Vincent

    vincent@freenet.vancouver.bc.ca      % Disclaimer: all I know I

                                         % learned from reading Usenet.