Re: Bipedalism
J. Moore (j#d#.moore@canrem.com)
Thu, 8 Jun 95 10:52:00 -0500
Rl> Harry sure does remind me of my graduate days at berkeley in the '60's.
Rl> Gorillas coming down to the ground to escape predators.
(That would be "students coming down to the ground to escape Guardsmen",
Ralph. ;-)
Rl> Just how many
Rl> instances have you seen of this action? How much do gorillas weigh? Why
Rl> would they be so stupid as to brachiate away in fear through the trees
Rl> when they can place their 600 pounds on the ground and intimidate just
Rl> about any other animal besides ourselves.
It would be odd if they did, since the only members of the troup who'd
be light enough to count on being able move tree-to-tree are the kids.
And Harry's "heavy ape=knuckle-walker" "light ape=bipedal" seems to
leave us with no chimpanzees, suggesting [he said dryly] that it's not a
correct dichotomy.
Rl> As for Oxnard, whom I deeply
Rl> respect, his analysis is probably based on some multiple discriminant or
Rl> componet analysis, which isn't really evidence but is a technique (or
Rl> set of them ) used to shore up an hypothesis or an interpretation.
Rl> SAgain, the question is Harry's attribution of a set of terrestrial
Rl> adaptations more evolved than in Australos (graciles too) and Homo
Rl> habilis. Knuckle walking is surely one adaptation to a terrestrial
Rl> habitat, but so is bipedalism, and it stretches the meaning of either of
Rl> these different adaptations to call one more terrestrial than the other.
Or for that matter, to say one or the other is more specialized. If
science was conducted as formal debate (which it all to often [and
unfortunately so] is) I'd say you could argue either of those propositions
equally well (either more or less terrestrial; or either more or less
specialized), which is not to say that either is valid.
Rl> And for OH62, it would be neat if we had some decent cranial
Rl> evidence with it. Limb proportions from fragmented postcranials are not
Rl> the soundest evidence, given that we lack any real knowledge of such
Rl> variation 1.8 million years ago.
Other than knowing that what we do see of the habiline skulls shows an
awful lot of variation there; why wouldn't we expect to see extremely
varied creatures underneath all those variable heads? Makes that a
particularly unfortunate period to not have more post-cranial stuff.
Rl> An can all of the stress analyses done
Rl> only come up with climbing as the what is being adapted to? Would
Rl> dragging carcasses around provide the same stress patterns?
It's an example of getting a bit too adaptionist, or perhaps getting too
far into the bones and biomechanics to look around at the many different
things that living primates do with their bodies. Dragging carcasses
(or parts thereof) might, and you could make a nearly endless list of
possibilities, starting with such likely activities as digging or
pulling up plants. It seems far more likely in a primate with a
generalized diet which has grown more generalized over time to have a
suite of behaviors affecting its adaption-selection, rather than just
the one, overriding behavior. Perhaps a more correct conclusion to such
a stress-analysis study could be "it shows that the adaptations seen
wouldn't hinder climbing, which might have still been a common behavior".
Rl> What else was around to make those footprints at Laetoli? Sasquatch?
Interesting that people who cite the lack of "Aquatic Ape" fossils as
a negative for that hypothesis can suggest that for a period where we
*do* have fossils, we just don't have any of the ones that made these
prints. Leaves a big hole for counter-attacks (anyone listening, Phil?:)
Rl> Finally, all
Rl> of observations of chimps and gorillas are on animals living in (now)
Rl> protected enclaves, and it is likely that their distribution over the
Rl> past few millions of years has been far more extensive and within an
Rl> arborial ecological niche far less broken than now (IMHO).
They may well have also ranged more widely in more open territory than we
now see them, and I believe we have reports of this for gorillas before
the introduction of guns. Just as with elk and big horn sheep in the
North American west, they may have taken to more and more remote areas,
as opposed to the flat lands they also used to use, under pressure from
weapons that are far more effective in open areas than what they faced
only a couple of centuries ago.
Rl> Nevertheless, that we debate these points is excellent, and shows
Rl> just how weak the fossil evidence, as well as much of our
Rl> functional analyses. Lets keep it up.
Rl> Ralp Holloway.
Good conclusions about the fossil record require a lot more
"intra-anthropological cross-pollination" than some of researchers want
to do. You see it in both "stones and bones" people and in "molecular"
people; others usually don't make quite the same sweeping conclusions,
so they often avoid tripping up in spite of themselves. (It might not be
such a problem, if it weren't for some of them having arrogant attitudes
and the whole field seemingly inspiring animosity.) Given the amount of
relevant material, it is probably impossible to trip over your own
tongue ocassionally (how do *I* know this? ;-) Actually, this
newsgroup has been pretty good, as on-line forums go; hope I didn't jinx
it by saying that.
(BTW, my favorite parody of adaptionist theory was Boule's Cornelius,
the chimp scientist in Planet of the Apes, who explained to the hapless
human that apes had become more intelligent than humans because they had
four hands, which rather obviously required more intelligence to
coordinate, since this allowed them to manipulate objects in more complex
ways than the poor two-handed humans. Makes perfect sense.)
Jim Moore (j#d#.moore@canrem.com)
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