Re: AAT Theory

H. M. Hubey (
17 Sep 1995 12:23:05 -0400 (Phillip Bigelow) writes:

> (J. Moore) writes:

>>bear. But you're right when you say that the case of the polar
>>bear is indeed a grave challenge to the AAT. The challenge, of
>>course, results from the fact that the polar bear seems not to have

>It should also be noted that, from a "comparative anatomy" view, there is
>nothing in the polar bear's anatomy (skeletal or soft tissue) that supports
>an "aquatic" or "semi-aquatic" adaptation. Now.. since Ms. Morgan stresses
>comparative anatomy as her "evidence" for an aquatic past for hominids, the
>polar bear analogy shows that "comparative anatomy-as-evidence" has severe
>limitations, particularly when it is used to suggest behavioral adaptations.

There's no question that

1) it is a challenge
2) it has limitations

but it's not a killer of AAT. First let us note that among the
aquatic animals such as whales, porpoises, manitees etc one thing
that has happened is that they have certainly become more
"streamlined" in the sense of the drag being taken out of the
rear appendages so that the whole body presents a shape more
like a pole rather than a tree with trunks (like four legged
animals). So in the extreme cases the streamlining effect on
the general skeletal shape is there. Even the otter when seen
swimming in water doesn't look like say a dog thrown in water;
its swimming shape is exactly like what we expect.

The problem in determining the effect of the aquatic environment
on the physical shape has to take into account two factors

1) the time that the animal went aquatic
2) the time that the animal stayed in the environment

I don't see any reason to assume that an animal that went
into the water at a very late period in its development and
stayed there much less than some other animal has to have
the same shape. This much seems obvious.


Regards, Mark