Race-Related IQ

Guy F. Barbato gfb1 at psu.edu
Fri Dec 2 11:29:43 EST 1994

In article <3blfnv$ind at nntp1.u.washington.edu> toby at u.washington.edu (Toby Bradshaw) writes:
>Path: news.cac.psu.edu!news.pop.psu.edu!psuvax1!rutgers!gatech!howland.reston.ans.net!vixen.cso.uiuc.edu!news.uoregon.edu!netnews.nwnet.net!news.u.washington.edu!toby
>From: toby at u.washington.edu (Toby Bradshaw)
>Newsgroups: bionet.general
>Subject: Re: Race-Related IQ
>Date: 1 Dec 1994 21:38:07 GMT
>Organization: University of Washington, Seattle
>Lines: 33
>Message-ID: <3blfnv$ind at nntp1.u.washington.edu>
>References: <3bavji$pke at news.iastate.edu> <mwspitze-301194133515 at phar2.medsurge.hsis.uci.edu> <3bksns$bje at nntp1.u.washington.edu> <mwspitze-011294091932 at phar2.medsurge.hsis.uci.edu>
>NNTP-Posting-Host: stein1.u.washington.edu

>In article <mwspitze-011294091932 at phar2.medsurge.hsis.uci.edu>,
>matt spitzer <mwspitze at uci.edu> wrote:

>>I think we're in agreement about the definition being the big problem.  But
>>my question is this:  Suppose that general intelligence does not exist, and
>>that IQ simply represents an average of performance on a number of
>>independent cognitive tasks.  Then what do we gain by using the composite
>>score, as opposed to the list of individual test scores? It seems to me
>>that the profile of individual test scores would provide much more

>I've never mentioned IQ tests specifically because I have no idea
>what component of "general intelligence" they might measure.  My major
>points are that:

>1) the heritability of components of human intelligence is, in principle,
>        estimable

>2) such heritability estimates have intrinsic scientific merit as objects
>        of research

>3) the genetics of "intelligence" are as amenable to study as other
>        quantitative traits that have complications of phenotype definition
>        and likely genetic heterogeneity

>I reject the notions that research into the genetics of human intelligence
>is *inherently* flawed or racist, that no component of "intelligence"
>is quantifiable, and that estimates of heritability are useless for
>any purpose but selective breeding.

>-Toby Bradshaw
>toby at u.washington.edu

Sorry, but you can reject the notion of 'heritability as being useless for any 
purpose but selective breeding' all you want...it is nonetheless true.

the concept of heritability is used to define the proportion of additive 
genetic variance in a *population* for the sole purpose of defining *breeding 
value*.  to suggest that heritability is intrinsic or even relevant to 
educational strategy is also fallacious.  each child enters school with 
certain attitudes and abilities determined by his family and environment, 
and to some undetermined (and undeterminable) degree due to genetics. 
however the school tries to optimize the individual childs' content of 
instruction to accomodate individual differences for some expected outcome.

if you still want to calculate heritabilities, great.  BUT remember that 
heritability estimates are unreliable when environmental factors are 
nonrandom across families, which presupposes genotype-environment 
correlations and underestimates the environmental contribution to group 

in fact, if one wants to pursue the concept of the inheritance or the genetic 
nature of intelligence (IQ test-determined, or some other concept), it seems 
to me that by focussing on heritability one completely ignores non-additive 
gene action (i.e., dominance and epistasis).  I could create a lovely just-so 
story, revolving around the fitness value of intelligence, and therefore, most 
of the genetic variation *should* be non-additive!!  Interestingly, twin 
models used to calculate heritability of IQ specifically overestimate 
dominance and epistasis.....Curiouser and curiouser.

ANYWAY, the genetics of individual differences (in humans) is an interesting 
academic problem which is probable insolube without the randomization of 
environments....or maybe a selection experiment   <ok...it was a bad joke>

cheers ------------ GFB
        G. F. Barbato                         Phone: (814)-865-4481
        Dept. Poultry Science                 FAX:  (814)-865-5691
        Penn State                            Lab:  (814)865-5691
        University Park, PA                   Email:  gfb1 at psu.edu
   ////  On induction, or 'Why do you believe the sun will rise tomorrow?"
  < * )         The farmer who has fed the chicken every day throughout
    \  \___///  its life at last wrings its neck instead, showing that the
    (  ---  )    more refined views as to the uniformity of nature would
      \/ \/     have been useful to the chicken.  ----- Bertrand Russell

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