Re: Alex's gibbon-like CA
Paul Crowley (Paul@crowleyp.demon.co.uk)
Mon, 06 Nov 95 01:58:01 GMT
In article <46kapq$2sl@geraldo.cc.utexas.edu>
aduncan@mail.utexas.edu "Alex Duncan" writes:
> In article <814581738snz@crowleyp.demon.co.uk> Paul Crowley,
> Paul@crowleyp.demon.co.uk writes:
> I personally don't have any problem w/ the idea of gibbon-like
> protohominids traversing 50 - 100 m of open space to get from one patch
> of trees to the next.
I don't have any problem with this either. But think about how much
time the protohominid spends "bipedaling" as a proportion of its
normal life - a very small percent; and, as far as it's concerned,
the smaller the better. It will do all it can to minimize time on
the ground. This is what is fundamentally wrong with your gibbon-
like CA. New adaptions are not acquired "reluctantly". Change is
hard enough to introduce at the best of times. If a species is going
to do something new, it's got to be something that it enjoys. It's
got to be an opportunity that it grabs with vigor and aggression.
To get at this more scientifically; Can you give any example of any
species adopting a form of behaviour for which it was apparently
quite ill-adapted? A solid example, please - not a "maybe".
> A protohominid faced with thinning forest may have had to change its
> dietary emphasis, but it's unlikely that it would have had to discover
> entirely new kinds of food.
I'm sure this is the "evolution forces" error. A species faced with
a shrinking habitat does not change its diet. It declines or dies.
We could look at squirrels as an analogy. They are nearly everywhere.
They spend a lot of time on the ground and must sometimes, reluctantly,
travel some distances. But nothing could ever "force" them to forget
their life in the trees. If all trees became 200 metres apart, they
would not lose their bushy tails, diurnal habits and climbing
adaptions. They'd just go extinct.
Thanks for the rest of your detailed response. I think that we've set
out our respective positions adequately so I won't reply to your other
points unless you ask.
Paul.
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