Re: AAH
Pat Dooley (patdooley@aol.com)
5 Dec 1994 23:55:15 -0500
In article <CzAD0q.21t@microsoft.com>, russpj@microsoft.com (Russ
>Paul-Jones) writes:
>
>1. It is hard to know what kinds of characteristics to look for,
> since I don't know what the AA looked like, and I don't know
> what mechanisms preserved the aquatic adaptations during
> millions of years of evolution in a non-aquatic environment.
> This objection is pretty much keeping the hypothesis, well,
> hypothetical in my mind. I want a model for the AA critter
> and some predictions for the chain of critters between us.
>
The starting point has to be creature that was the common ancestor of
gorillas,
chimpanzees and humans. Given that starting point, and I suspect it wasn't
that much different from a modern ape (homo sapiens excepted!), one needs
to look at what adaptations could be made if such a creature was to become
partially adapted to aquatic life. The probiscus monkey provides some
clues
as do Japanese Macaques.
The other starting point is to look at the characteristics of other
mammals that
have made to the transition to aquatic life.
If we ignore the AAT at this point, and pose the hypothetical question of
what evolutionary
changes would we expect if we forced a forest ape to adapt to an aquatic
life, we might
get a few hints. How could we force the ape to adapt? Place it on an
island and slowly dry
out the forest cover.
Would it be hairless?
Above a certain mass, aquatic and wallowing mammals are hairless.
Would it have subcutaneous fat?
Since this contributes to thermal insulation, bouyancy and streamlining,
and is
universal amongst aquatic mammals, you would have to suppose our ape
would be fat.
Would it be bipedal?
If its ancestor was a arboreal and/or a knuckle-walker, then bipedal makes
sense.
Probiscus monkeys have been filmed walking bipedally. Macaques wade into
water. Wading on two legs makes more sense for an ape than reverting to
four
legs, like a herbivore.
One could go on, but you get the general idea.
>2. This is why I think that my first objection will be so hard to
> satisfy. It will be hard to design a mechanism for maintaining
> those aquatic adaptions modern humans have that doesn't also
> work as a reason to evolve them in a non-aquatic environment.
> If subcutaneous fat is advantageous in a savannah environment,
> then we don't need the AAH to explain it's existence in modern
> humans. If it is not, then the AAH has quite a bit of
> explaining to do to show why it survived until modern times.
>
If subcutaneous fat was an advantage in a savannah environment, then it
would
be as universal amongst savannah animals as fur. Nobody that I have read
has been
able to make such a case.
Pat D responding once more.
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