Re: AAT Theory
David L Burkhead (r3dlb1@dax.cc.uakron.edu)
9 Oct 1995 03:03:17 GMT
In article <hubey.813039992@pegasus.montclair.edu> hubey@pegasus.montclair.edu (H. M. Hubey) writes:
>r3dlb1@dax.cc.uakron.edu (David L Burkhead ) writes:
>
>
>
>>posters in this thread keeps pushing the aquatic phase back whenever
>>anyone points out that the trait he's postulating as an "aquatic
>>adaptation" predates the postulated "aquatic phase." And he
>>conveniently ignores or conveniently misinterprets having that those
>>traits _postdate_ any "aquatic phase."
>
>I also think that mammals probably developed in an aquatic
>environment. (I don't know if I read it someplace). The
>water would provide the necessary constancy which could
>account for the almost constant body temperatures of mammals
>(and almost birds and marsupials). Most animals probably lived
>near water (they have to drink) anyway, and it would have been
>easy.
So now you've pushed it back to the Jurassic, or even earlier.
Unfortunately, mammals developed from proto-mammals such as
dimetrodon, which developed early forms of temperature regulation in
anything but an aquatic environment. And themperature regulation has
advantages that any zoologist could list for you, advantages that
don't require an aquatic environment to become apparent.
For that matter, your postulated "constancy" would argue
_against_ developing temperature regulating systems. Temperature
regulation (the key factor of warm-bloodedness) works to keep
temperature constant against _changes_ in the external environment.
No changes, no need for temperature regulation, no force to weed out
those that don't have it.
>Is it impossible for some place where forest and sea merge?
>There the apes would have had the perfect chance to go into
>water and even escape into the trees. The tree escape would
>have been easy in the beginning. In fact, this would be useful
>even for modern humans who were threatened with big cats. They
>can always climb trees, even now.
This is an almost worthless excercise. Pile enough assumptions
on your "theory" and you can make just about anything possible. (How
about those gene labs on 47 Ophiuchi III?). Ignore data that
contradicts your theory and you can "prove" just about anything.
BTW, there _are_ places where forest and sea merge--mangroves.
These are generally considered _extremely_ unhealthy places to be.
There are lots of concealed predators that just _love_ to lie in wait
for unwary primates that think this is a good place to escape from
other predators.
>PS. How about an explanation of the loss of body fur. In order
>for the heat loss calculations to work out, we'd need to be
>as large as elephants or rhinos, and even then it doesn't
>give any cause-effect.
"Heat loss calculations"? GIGO. Your "calculations" are no
better than the assumptions that go into them. Humans have
demonstrated one of the more impressive temperature regulating systems
on this planet. A human in high temperature conditions can literally
walk an ungulate to death (well, coup de grace is usually provided by
pointy stick or the equivalent). The combination of a well developed
sweat system and furless skin allow us to shed heat quickly (the usual
problem in savannah conditions--rather than the _reverse_ in aquatic
conditions). Upright posture helps for several reasons. Air near the
surface is usually noticably hotter than air a few feet up. During
the hottest part of the day, a human standing upright exposes less
surface to the sun than would a similar sized quadruped. Thus, humans
can be out and active when other animals are holed up against the
heat.
Loss of heavy fur is an important part of this. Those that had
"thinner" fur could function in hotter parts of the day than those
with heavier fur, leading them to be less culled by predation. The
result would be a bias toward less fur.
David L. Burkhead
r3dlb1@dax.cc.uakron.edu
d.l.burk@ix.netcom.com
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