Re: AAT Theory
H. M. Hubey (email@example.com)
26 Sep 1995 02:28:27 -0400
firstname.lastname@example.org (David L Burkhead ) writes:
> Also, "streamlining" depends greatly on position. For the wading
>ape that Morgan postulates it is almost entirely irrelevant. An
>essentially upright posture has so much form drag (mostly caused by
>flow separation) that short of taking a more horizontal posture (which
>lets the wind out of much of AAT's supposed "evidence's" sails)
>there's not much that can be done about it.
We have exactly the same problem with the savannah theory
assuming that it still exists :-)..
Today's humans have long legs and can run reasonably fast but
it seems they would have been faster on all fours. Besides, if the
knee joint had to go through the change from the quadripeds to
the humans, somewhere in the middle when the twisting and turning
was supposed to be happening (I guess at the hips too) the animal
would have practically been lame. Where could it have survived?
The theorizing in this field is like thermodynamics-- they
concentrate on states not the dynamic paths. If it were not
so how does anyone explain how some animals suddenly(!)
stopped laying eggs and decided to carry their babies inside
We see that they exist and try to go backwards even if
unsuccessful. We have streamlined humans without body
hair and with things like the diving reflex. The rest
is story making like all the rest.
> So, were our ancestors, who were the direct decendents of those
>aquatic apes, "streamlined"? It would not appear so.
It doesn't matter much to me. I'm convinced given the evidence
that the aquatic phase seems to hold promise. Maybe the aquatic
phase goes back even further and the apes of today came out of
the water and went into the trees and humanoid ancestors spent
more time in the water.
> Sigh. Go back and read what I said. Traits that we developed
>_after_, long after, any purported aquatic lifestyle was _over_ cannot
>be used as evidence for that lifestyle. Your citing grasping thumb
>and fingers is a total non-sequitor. If we developed those traits in
>an arboreal lifestyle then we had them then. It did not take several
>million years _after_ we climbed down from the trees before those
>hands showed up. _All_ of our ancestor species, right back to the
>earliest known hominids, had them.
I'm still not clear why it can't be so. Streamlining was a small
part of what I wrote about. If the changes had taken place in
response to water, then if the change was useful it would have
stayed, just like being able to grasp didn't go away when our
ancestors came out of the trees because it was useful.
Besides, as I wrote in another posting, maybe the whole
hand and foot changes in proto-humanoids did develop in water.
For example long digits would make webbing useful but certainly
not something like a dog's paws. A wide foot with webbing would
make swimming easier. And it didn't have to mean that the hair
was lost by that time, since neither polar bears nor sea otters
have lost their hair. Some of the could have gone onto the
trees and others stayed in the water longer.
>lifestyle, then the trait would have to have developed _while we were
>still in the water_. Since A. Afarensis does not have such
>streamlining, the aquatic phase would have had to have been _after_
Everything is relative. If it doesn't look just like a monkey
and is even slightly more bipedal it is more "streamlined" and
we don't know if it had webbing to make up for its lack of more
streamlining and I guess we don't know if it had hair either.
>i.e. that humans have a lower Cd when swimming or wading (mostly
>wading since that's what the theory is based on) than would chimps or
>gorillas, or whatever ape most closely approximates the common ancestor.
Wading, swimming, diving, dunking, what is the big deal?
Wading is just a word; I assume it was meant to explain how
they got started.