Re: Moorad's comment is sound

On 6/30/05, Don Winterstein <dfwinterstein@msn.com> wrote:
> 
>
> Rich Faussette wrote:
>
> "If the mean IQ of the population is two standard deviations above that of surrounding populations, a regression to the mean from generation to generation would still result in higher IQs relative to outgroups...."
>
> OK, but you didn't answer my question. Granted, if AJ start out with a genetic advantage, the advantage is likely to continue if they don't breed outside their own group. But aren't you assuming that they didn't start out with the advantage, but that it accrued as a result of self-selection? So the unanswered question is, if they started in the same place as everyone else, how did they make their gains? I don't see how this was possible unless they somehow kept their low-IQ members from breeding. In every society smart people tend to marry smart people; but you don't get a shift in the peak of the IQ distribution, because dumb people keep marrying dumb people.
>
> If IQ were highly heritable, you'd soon get the highs diverging tremendously from the lows. This doesn't seem to happen. Brilliant people regularly emerge from the lowest strata. So maybe the absence of this predicted effect constitutes evidence that IQ is very weakly heritable--and hence not a good target trait for eugenics programs.
>
> Don
>

IQ itself is probably not highly hertiable but frontal cortex brain
size appears to be. Note the following from Nature Neuroscience 4,
1253 - 1258 (2001):

----
Cognitive linkages
To make a preliminary assessment of whether gray matter differences
between subjects were significantly linked with differences in
cognitive function, a cognitive measure termed 'Spearman's g' was
assessed for all 40 twins. Like IQ, this widely used measure isolates
a component of intellectual function common to multiple cognitive
tests, and has been shown to be highly heritable across many studies,
even more so than specific cognitive abilities (h2 = 0.62 (ref. 4,
compare with ref. 24); h2 = 0.48 (ref. 33); h2 = 0.6−0.8 (ref. 34,
compare with refs. 35, 36, 37, 38)). **We found that differences in
frontal gray matter were significantly linked with differences in
intellectual function** (Table 1; p < 0.0044; p < 0.0176 after
correction for multiple tests) as quantified by g, which was itself
also highly heritable (h2 = 0.70  0.17 in this study). Although these
preliminary correlations should be evaluated in a larger sample, a
recent abstract also observed that differences in regional gray matter
volume were significantly correlated with differences in IQ, in a
sample of 28 pediatric MZ twin pairs (mean age, 12.1 years) studied
volumetrically (E.Molloyet al., 7th Annual Meeting of the Organization
for Human Brain Mapping,  447, Brighton, England, 2001). [emphasis
mine]
----------
It should be noted is there is also plasticity in the brain. Heavy
intellectual activity also produces such a similar effect (Trends in
Neurosciences, 23, 475-483). One way to look at the genetic effect on
the brain is to look at autism. This is personal to me because I have
a son who is autistic. A pattern I saw when someone was autistic was
that the father was invariably an engineer.  Ultraorthodox Jews seem
to also have a prevalence of autism (Soc Sci Med. 2005 Jun 17).
Autistic toddlers have on average 12% more gray matter in their
cerebral cortex, according to a 2001 study by neuroscientist Eric
Courchesne of the University of California, San Diego, and his
colleagues. In unpublished postmortem studies, Courchesne's group has
found a large excess of a special class of pyramidal neurons in the
frontal cortex. Note the following from Science (Science, Vol 308,
Issue 5724, 948):
----
Mating for Autism?
If cases of autism are on the increase, as some believe, here's one
provocative explanation: Blame the rise on marriages between
like-minded people, whom psychologist Simon Baron-Cohen of Cambridge
University in the U.K. calls "systemizers."
Baron-Cohen argues that autism and related conditions like Asperger's
are manifestations of what he calls the "extreme male brain": one with
weak social skills and a strong tendency to "systemize," or think
according to rules and laws. In a study of 1000 U.K. families, he has
reported that the fathers as well as the grandfathers of children with
autism spectrum conditions are more likely to work in professions such
as engineering. And the mothers are also likely to be systemizers
"with male-typical interests," he says.
Baron-Cohen, whose theory is in press at the journal Progress in
Neuropsycho-pharmacology and Biological Psychiatry, says he and
colleagues are performing genetic studies, collecting subjects, and
conducting population surveys in systemizer-heavy areas, such as
Silicon Valley, to test the idea that techies marrying each other is
raising autism rates.
Some balk at the idea. Psychologist Elizabeth Spelke of Massachusetts
Institute of Technology says there's no good evidence for an "inborn,
male predisposition for systemizing." But psychiatrist Herbert
Schreier of Children's Hospital in Oakland, California, believes the
intermarriage of techies "probably does account for why you have
pockets of high autism around Stanford and MIT." Drawing on his own
practice, he adds that fathers of children with learning disabilities
have a disproportionate tendency to be engineers or computer
scientists.
---
So, yes, mating for large frontal cortex size may work. But, you can
also get a similar effect via higher intellectual activity. This is
also without the negative effects such as LSD and autism. We should
follow the ultraorthodox Jews by promoting greater scholarship in our
children but we need to eschew their inbreeding and eugenic practices
as fundamentally unhealthy.