Re: Braindance
J. Moore (j#d#.moore@canrem.com)
Wed, 17 May 95 13:36:00 -0500
Ka> I've just read Dean Falk's Braindance and I'd like to hear other
Ka> people's opinions about what she said. She seems to bring up a lot of
Ka> good points and theories (using blood flow to cool of the brain is one),
Ka> but she seems to cover some areas very slightly and skip some things
Ka> entirely.
Ka> I don't entirely buy her theory for the origins of bipedalism
Ka> itself. If Australopithecines lived in a cooler environment, why would
Ka> they need to become bipedal?
I've found it helpful to pretty much wipe the words "why would they
need to" or "why wouldn't they" right out of the vocabulary when
talking about evolution.
They didn't "need to" become bipedal; they could've done something else
and become something else. (Like become quadrupedal and be a chimp.)
It just turned out that some populations of the common ancestor used
bipedalism habitually, and completely coincidentally, it turned out to
be more useful in a variety of habitats than that quadrupedalism stuff.
Ka> If Aust. lived in
Ka> cooler environments than Homo, they should have had bigger brains than
Ka> the earliest Homos becuase their brain size was not held in check as
Ka> much by high temperatures-- does the fossil evidence show this?
Increased brain size isn't necessarily useful. If your species finds it
can get by just dandy without bigger brains, they won't produce them
just because they *could*.
Ka> most of the theories that I have heard for the extinction of Aust. is
Ka> that their habitat dissapeared with the increasing aridity of the time.
Ka> Should not Aust. have made an attempt to expand into other niches?
Ka> Perhaps the same savanah niche being exploited by Homo? Was perhaps
Ka> Homo's dominance of the savanah niche too strong to allow Aust. any room
It would seem that *Homo erectus* was a pretty effective animal in an
even wider variety of habitats than were australopithecines. There were
no niches available to the remaining australopithecines that weren't
available to erectus. They were much longer legged and bigger brained,
and that gave them important advantages in food-getting, and probably
food-preparation (wider range of food available) and social skills.
Although australopithecines hung around for a goodly while contemporary
with erectus in Africa (a few hundred thousand years), all it would take
were some bad times and the more effective skills of erectus as opposed
to australopithecines could make the difference between life and death.
Ka> If Homo was so dominant, why are their fossils so rare?
Well, most all hominid fossils are rare compared to pigs. But hominid
fossils are incredibly abundant compared to apes of the same period.
A lot depends on whether or not you die in a place that promotes
fossilization. (Habitual living in heavily forested areas, especially
wet forest, would tend to lessen the likelihood of fossilization;
hanging around wallows or habitually living on the shores of lakes and
streams would tend to create an extremely rich fossil record. The
fossil record of hominids suggests that, although they could have
sometimes lived in forested areas [we'd tend to not find those fossils
if they did], they probably did not hang out on the shores [or we'd find
a lot more of them].)
Jim Moore (j#d#.moore@canrem.com)
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