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In a message dated 8/9/98 12:17:07 AM Eastern Daylight Time,
sarima@ix.netcom.com writes:

<< The earliest hominids (_Australopithicus afarensis_ and its predecessors),
 were within the smaller size range, being about the size of a bonobo.
 Thus, in hominids, bipedality probably *did* originate due to loss of
 arboreality. >>

I sent a post related to this topic last week from my other location, but it
never appeared.  Perhaps someday it will pop up.  I don't have the reference
materials with me, but if my original post ever shows up the references are in

That post mentioned an article in the current issue of the Journal of Human
Evolution (also summarized in the August National Geographic) which concludes
that Australopithicus afarensis (Lucy) was probably not on the direct line to
Homo habilis.  The problem arose when new material and a closer examination of
previously recovered material demonstrated that A. africanus and H. habilis
shared characters that were more primitive (relatively longer arms, shorter
legs) than their presumed ancestor, Lucy.  Rather than accept that Lucy's
descendants underwent an evolutionary reversal to a more arboreal existence,
the authors concluded that A. africanus, not Lucy, was on the direct line to
Homo habilis.  Since Lucy is older than A. africanus, but more derived with
respect to some bipedal characters, the authors also suggest that bipedalism
arose at least twice among the australopithecines.

It appears that we may have lived an arboreal life longer than previously
thought.  And it is interesting to see another branch of science wrestle with
issues such as evolutionary reversals, similar evolutionary innovations
popping up more than once in the fossil record and speculations about the role
of arboreality in the process.