🚀 go-pugleaf

[Note -- I have directed followups to sci.bio and sci.misc, since I
don't really feel that this is a sci.philosophy.tech subject.]

In article <123@snark.UUCP> eric@snark.UUCP (Eric S. Raymond) writes:
>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.

	Well now, the evidence is not nearly so strong as you claim.
The principle results on identical twins were those of Cyril Burt's,
which is where the conventional figure of 80% heritability comes from.
However Burt's data and results were forged.   (I don't know if this is
mentioned in Gould, but it is well established.)  The reason you don't
have the statistics at hand for identical twins is because it doesn't
exist, apart from Burt's forged data -- there is some data but it is very
sparse.

>'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

	I have a copy of Cattell's classic work on the subject.  On the
whole one has to be impressed, and I am inclined to believe that there
is such a thing as general intelligence, with a reasonably high heredit-
ability.  However I have a lot of caveats.  Firstly, factor analysis is
a linear analysis method which can break down if there are nonlinearities
in the underlying factors.  Secondly the correlation analysis is the
isolation of agreement between results on tests (lots of them).  The
tests themselves, however, are not culture free (if there is such a
thing as a culture free test.)  This is a notorious problem -- the early
workers in IQ testing, Terman, et. al. had no trouble believing that
immigrants from Eastern Europe all had abysmally low IQ's because that
is what their tests showed.  Psychometricians today have a much clearer
understanding of these difficulties.

	Again, the degree of cultural inhomogeneity affects the
determination of the heritability figure [which is not a simple
fixed number, by the way.]

>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.

	Marxist sympathies!!??  What an odd thing to say.  I will also
endorse the book, even though I also have reservations about some of
his analysis.

>
>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.
>

	True enough, that there "seem" to be hard limits set by heredity.
Since the nature and operation of the underlying factors are unknown
it is indeed hard to say much more than that legitimately.  The
politics arise because people extrapolate wildly from what is actually
known and use those extrapolations to buttress preconceived political
viewpoints.  It's all bad science.  We have nothing like a good physical
model of general intelligence -- we don't even have a good identification
of what is meant by the term.  

>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.

	A relevant point:  In Japan there is a 'caste' roughly equivalent
to the untouchables of India.  Now the segregation of this caste (whose
name I don't recall but it starts with an 'h') occurred only a few hundred
years ago and was occupationally based.  Accordingly there is no good
reason to believe that the caste is genetically any different from the
population of Japan as a whole.  Same gene pool, arbitrary splitting off
of an oppressed class.  This class, as a group, scores about 15 points
lower in IQ tests than the general population of Japan.  Oddly enough
this is about the same differential as that between whites and blacks
in this country.


>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.

Your observations on the political correlations are probably correct.
One's science in these areas tends to strongly affected by the political
views that one holds.  More importantly, holders of particular views tend
to select "scientific results" that support the views that they hold.

Intellectually honest scientists recognize that we don't know enough
to legitimately make any such claims.  The only correct anwer to
"Who are right, the hereditarians or the environmentalists?" is
"I don't know".

>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.
>
If one is inclined to be charitable, the best that can be said for Sociobiology
is that it is speculative.  In view of the recurrent tendency to set public
policy upon ill-founded speculation masquerading as science, I suppose there
is something to be said for having a balance of such materials available.
-- 

Richard Harter, SMDS Inc. [Disclaimers not permitted by company policy.]