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From: eric@snark.UUCP
Newsgroups: sci.philosophy.tech,sci.bio
Subject: Re: Knowledge and the Academics
Message-ID: <123@snark.UUCP>
Date: Sat, 13-Jun-87 01:20:19 EDT
Article-I.D.: snark.123
Posted: Sat Jun 13 01:20:19 1987
Date-Received: Sun, 14-Jun-87 01:52:43 EDT
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Xref: utgpu sci.philosophy.tech:169 sci.bio:367
Summary: intelligence is *extremely* heritable

In article <2172@mmintl.UUCP>, franka@mmintl.UUCP (Frank Adams) writes:
> I am curious about why "is intelligence heritable?" was included in this
> list.  This seems to me to be very much a scientific question, albeit one we
> can't really answer yet.

Intelligence is *extremely* heritable. The results that show this are solid
but not as well known as they might be due to the fact that hereditarianism
in general is out of fashion and 'politically incorrect'.

Empirical evidence: the I.Q. and aptitudes of identical twins raised apart are
quite strongly correlated -- sorry, I don't have numerical statistics handy.

'Intelligence' is a multidimensional composite of aptitudes in several
distinct areas. However, factor analysis on the results suggest that about
half the variance is due to a single 'hidden variable' which some
psychometricians call xxxx's q, where xxxx is a psychometrician's name
that I can't recall right now -- something like Jensen or Ivorsen. This
q factor is about 80% heritable.

Certain specific talents generally thought of as forms of intelligence -- such
as mathematical and musical ability -- have long been known to be that
heritable.

All of this data is discussed, from a strongly environmentarian viewpoint,
in Stephen Jay Gould's _The_Mismeasure_of_Man_ -- a book I recommend for
facts and style while disagreeing almost totally with its analysis and
conclusions. Gould is a fine and lucid writer when his Marxist sympathies
are dormant.

What seems to be true is that heredity sets a fairly hard upper limit on
the capability of the brain to do particular kinds of information
processing (things like, say, spatial visualization). Whether that
limit is ever pushed depends on the individual's environment. Nearly
all psychometricians agree on this much. Go any further and you get
into controversies with such heavy political overtones that it's hard
to see light through the smoke.

Environmentarians believe the inherited limits are generally well above
the performance level of typical individuals, so that there's plenty
of room for improving the masses by improving things like richness of
early environment, education, etc. This tends to correlate a more
general beief in human perfectibility and with politics that are
statist-liberal, socialist or Marxist.

Hereditarians believe that individuals routinely push their inherited
limits; you can and should train an individual up to maximum, but unless that
person has been lucky in the genetic draw that maximum will be at or below
average for the population. This tends to correlate with conservative,
religious-fundamentalist, reactionary and fascist politics.

Historically, psychometrics has swung like a pendulum between hereditarian
and environmentarian extremes, often in a way correlated with the political
ideology of the period's dominant culture. The late 1800s saw an extreme of
hereditarian dogma (the Nazi master-race bulls**t was a sort of degraded pop
version of stuff that was mainstream scholarly anthropology in 1850-1900).
The 1960s saw an extreme of environmentarian dogma, more recently corrected
by the influence of Wilson and the sociobiological school.

My personal opinion: the hereditarian claim is unpleasant, but fits the 
observed statistical facts better than most versions of the environmentarian
thesis. Attempts by Gould and others to dismiss the q-factor as an artifact
aren't convincing, particularly since they tend to fall back on ad-hominem
attacks on infamous hereditarians of the past when reasoned argument fails.

(My politics, you ask? A fair question. Libertarian -- I loathe the left
and right with equal intensity...:-))


-- 
      Eric S. Raymond
      UUCP:  {{seismo,ihnp4,rutgers}!cbmvax,sdcrdcf!burdvax}!snark!eric
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      Phone: (215)-296-5718