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From: gallagher@husc4.HARVARD.EDU (paul gallagher)
Newsgroups: sci.bio
Subject: Re: Why are Humans as Smart as They Are
Message-ID: <2737@husc6.UUCP>
Date: Sun, 23-Aug-87 18:44:49 EDT
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Posted: Sun Aug 23 18:44:49 1987
Date-Received: Mon, 24-Aug-87 00:39:08 EDT
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Reply-To: gallagher@husc4.UUCP (paul gallagher)
Organization: Harvard Univ. Science Center
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A book, perhaps a little out of date, on this subject is R. Lande's
Evolution of the Brain and Intelligence (1973).  But before one starts
making up adaptive stories to explain the origin of any biological feature, it
is important to know precisely what are the traits that you are examining and
to consider the possibility that a given trait is merely the correlated 
consequence of selection directed elsewhere.  For example, it might be a
mistake to regard the human chin as a unitary trait requiring adaptive
explanation; it could be regarded instead as a byproduct of the interaction of
the alveolar and mandibular growth fields, which would lead to a very different
interpretation of its origins (see Stephen J. Gould's Ontogeny and Phylogeny,
pp. 381-382).

Also, it is important not to confuse cultural adaptation (with heritability
imposed by learning) and physiological adaptation (the phenotypic
plasticity that permits organisms to change during the course of their
development) with the sort of adaptation that arises from the action of
selection upon genetic variation.  It is also important not to confuse
the current utility of a trait with the reasons for its origin.  And it
is important to remember that even if an adaptive scenario is plausible,
it should not be accepted as true without *evidence*. 

One elegant interpretation of the origin of human intelligence involves
neoteny: we are permanently juvenile apes.  See Stephen J. Gould's Allometry
in primates, with emphasis on scaling and the evolution of the brain.  In
Approaches to primate paleobiology.  Contrib. Primatol. 5, 244-292.  Also,
see Gould's Ontogeny and Phylogeny. 

PG