Race-Related IQ

Guy F. Barbato gfb1 at psu.edu
Mon Dec 5 10:03:34 EST 1994


this was meant to be a post from Dec 4, 1994, to which i accidently "replied" 
via email....oops.....sorry, toby, i'm still pretty new to this concept!! : )  
i'm going to try to figure out how to post toby's reply
 guy

To: toby at u.washington.edu (Toby Bradshaw)
From: gfb1 at psu.edu (Guy F. Barbato)
Subject: Re: Race-Related IQ
Date: Sun, 4 Dec 1994 17:17:18 GMT
Message-ID: <gfb1.28.2EE1F99E at psu.edu>
X-status: N

In article <3bnria$bem at nntp1.u.washington.edu> toby at u.washington.edu (Toby Bradshaw) writes:
>Path: news.cac.psu.edu!news.pop.psu.edu!psuvax1!gvls1!udel!gatech!howland.reston.ans.net!vixen.cso.uiuc.edu!news.uoregon.edu!netnews.nwnet.net!news.u.washington.edu!toby
>From: toby at u.washington.edu (Toby Bradshaw)
>Newsgroups: bionet.general
>Subject: Re: Race-Related IQ
>Date: 2 Dec 1994 19:12:10 GMT
>Organization: University of Washington, Seattle
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>Message-ID: <3bnria$bem at nntp1.u.washington.edu>
>References: <3bavji$pke at news.iastate.edu> <mwspitze-011294091932 at phar2.medsurge.hsis.uci.edu> <3blfnv$ind at nntp1.u.washington.edu> <gfb1.27.2EDF4B76 at psu.edu>
>NNTP-Posting-Host: stein1.u.washington.edu


>In article <gfb1.27.2EDF4B76 at psu.edu>, Guy F. Barbato <gfb1 at psu.edu> wrote:

>>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.

>Assertion does not constitute proof.  Perhaps you have more to offer.

true. assertion does not constitute proof, although there is a point where a 
good course in quantitative genetics is recommended...please see textbooks: 
Falconer (any edition), Pirchner, 1983, Mather and Jinks, 1972, Jacquard, 
1970(english translation --great text, BTW)..this is just a short list of my 
'favorites', please feel free to check yourself

>>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*.

>Perhaps you can point to a post where I, or anyone, mentioned narrow-sense
>heritability.  For broad-sense heritability, additive variance is
>irrelevant.

perhaps you didn't specifically mention narrow or broad sense at all.  Using 
vaque terminology in posts, then pleading innocence for not being more 
specific later smacks of the "oversimplification", if not "special pleading"  
   : )

however, additive variance is *not* irrelevant to broad sense heritability, it 
is a portion of the total genetic variance.

>>to suggest that heritability is intrinsic or even relevant to
 >>educational strategy is also fallacious.

>Strawman.  Perhaps you can point to a post where I claimed it did.

so it goes

>>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. 
>                               ^^^^^^^^^^^^^^
>Why is this so?

except for special circumstances (e.g., single gene traits or chromosomal 
abnormalities) one cannot characterize the genetic contribution to an 
*individual* phenotype

>>however the school tries to optimize the individual childs' content of 
>>instruction to accomodate individual differences for some expected outcome.

>That is the rosiest scenario I can imagine, and quite at variance
>with my own experience with schools, but fantasy can be healthy :)

this is the difference between an optimist and pessimist. 
IMHO this is what the public school system was originally designed to 
accomplish.  not fantasy, but a lifetime goal

>>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 
>>differences

>Part of any good experimental design is to assure that as many of
>the assumptions of the chosen analysis are met as well as possible.
>Has this been done for heritability of human intelligence or IQ?
>I have no idea.  Perhaps you can show, rather than assert, that
>such an experiment is impossible.

actually, a simple place to look is in the literature.
a good starting place would be in ehrman omenn and casparis 1972 book entitled 
Genetics environment and behavior: Implications for educational policy
(nice book, often overlooked in these issues, but the commentary on invited 
papers is fascinating)....more current research by Plomin and associates 
points out the value of the genetic model in determining environmental 
influences....[ps - most of us at Penn State mourn his decision to move to 
cambridge, but are also happy he's happy!]

>>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).

>If I were discussing narrow-sense hertiability, you might have a point.
>You might want to re-read the earliest posts of mine in this thread.

>>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.

>Are you claiming that the twin models overestimate heritability due to
>non-additivity, or that only the *proportion* of nonadditive genetic
>variance is biased upward relative to the total genetic variance?  Unless
>you're interested in breeding, the partitioning of *genetic* variance
>components isn't necessary to determine the degree of genetic control
>of a trait.

hmmm....yes, no, yes (but not people), not.
heritability determined from twin studies overestimates heritability due to 
non-additivity (see Falconer or Ehrmann)....this has been known by dairy 
breeders since the late '40s early '50s.
further, the relative proportion of the types of genetic variation that are 
exhibited by a trait provide information for interpretation of the 
evolutionary history of the trait (see lewontin's work).  perhaps more 
importantly, the type of genetic variation defines the experimental 
methodology necessary to elucidate the nature of the genetic variation (both 
in a quantitative sense re:mather and jinks and in a biochemical sense 
re:lander and botstein) the wrong experimental design combined with and 
incorrect model applied to the wrong trait = disaster.

>>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>

>You might want to check into the trisomy 21 literature, which seems
>to explain individual differences in human intelligence
>in a very limited sense, and for which negative selection is performed
>routinely.

i agree, very limited. and not relevant to the population at large.

I don't know your background or training (obviously, or, perhaps, not-so-
obviously) i am a quantitative geneticist ... i used to say behavioural 
geneticist, but they can't get real jobs.  : )  ...

it is always curious to me the manner in which one field of study uses/adopts 
methodologies from other fields, many times it is the technical definition of 
common terminology that has intrinsically different meanings (and basic 
assumptions) in each field.  at least in this case (i.e., genes and 
intelligence) i defer to the commentary by Jerry Hirsch on potential 
pitfalls and pratfalls in this line of inquiry...see: To unfrock the 
charlatans in SAGE: race relation abstracts 1981...jerry was a bit criticized 
by the traditional animal behavior geneticists for getting into this argument, 
but his point of view reflects mine as well.


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

now i've got *real* work to do  : (
--- 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
  XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX


  =========================================================================
        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
  XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX




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