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From: aweinste@Diamond.BBN.COM (Anders Weinstein)
Newsgroups: sci.bio,sci.misc
Subject: Re: Knowledge and the Academics (really heritability & IQ)
Message-ID: <6566@diamond.BBN.COM>
Date: Mon, 15-Jun-87 12:43:10 EDT
Article-I.D.: diamond.6566
Posted: Mon Jun 15 12:43:10 1987
Date-Received: Sun, 21-Jun-87 01:56:05 EDT
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Reply-To: aweinste@Diamond.BBN.COM (Anders Weinstein)
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Xref: mnetor sci.bio:446 sci.misc:353

As I understand it, "heritability" is a rather bogus statistic from which to
draw political or sociological conclusions. Heritability indicates the extent
to which genes account for variance *within a population*. By itself, it
doesn't license any meaningful conclusions about the causes of differences
*between* populations (which is what is usually at issue in IQ debates).

Example: Take two identical samples, A and B, of genetically diverse corn,
and grow each in a controlled environment. Deprive one group, B, of some
essential nutrient. Both populations will exhibit variation in height. In each
group this is due entirely to genetics, so height is highly heritable in
each. But the fact that the average height in B is much lower than that of A
is *not* due to genetics; it is entirely environmentally caused.