On Tue, 9 Dec 2003 03:50:58 +0000 (UTC), tomhendricks474{at}cs.com
(TomHendricks474) wrote:

> Or is it the case that in the wild a creature will only
get enough food to
>> be able to survive, so must be the best it can be at it's job?
>> 
>> [moderator's note: I have thought about this myself: the adaptationist
>> ideal is that mere adequacy must be optimized -- that is, one must be
>> optimal just to persist. Is this true? -  >>
>
>I don't think so in every case. This was an assumption by Darwin that I think
>was false or at best unproven. He suggests that the food supply is not enough
>in every case, so selection follows. Yet that is a broad statement to make. 
>For instance herbivore insects in the rain forest will NOT run out of trees and
>leaves to eat. So in there case selection is not on the scarcity of food IMO.
>

There is an old joke about being chased by a bear.  You don't have to
be fast enough to outrun the bear, only fast enough to outrun your
companions!  "Optimal" in selection only means being better than the
competition.

Natural selection works by comparing two sets of organisms.  One group
may well out-reproduce the other because of some inherited set of
characteristics.  If there are limited resources so that only so many
total can survive, the less fit group will become extinct. This
general paradigm works so much of the time that it explains the major
patterns of evolution.  It does not operate in every case, though.  An
individual may survive and reproduce or die by simple dumb luck -- the
bear was facing the other way.  The resources may be ample and there
may be so few competitors that just about everyone does well -- as in
a founding population in a new habitat. You may not be all that good,
but nobody has yet figured out a better way -- as in the marsupials in
the Southern Hemisphere before the introduction of placentals.

In the long run, this tends towards optimization.  But we may be far
from equilibrium in particular cases.
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