From: Rafal Smigrodzki (rms2g@virginia.edu)
Date: Tue Oct 01 2002 - 08:20:18 MDT
spike wrote:
>
> Do we need any other explanation beyond this one?
> Could inbreeding play a role? Would that in general
> reduce the *average* IQ of an isolated community? spike
### Yes, inbreeding is associated with a significant drop in IQ. Additional
factors in isolated communities might be lack of adequate nutrition, lack of
intellectual stimulation (which results in the inability to intellectually
stimulate others, which results in the inability...yes, the vicious circle).
In fact, the interplay between minor genetic differences and minor initial
environmental differences can magnify differences between groups quite
significantly. Slightly less smart persons produce or seek environments
which are less conducive to their intellectual development. This observation
is the basis of Dr.Flynn's recent explanation of the Flynn's effect, at:
Dickens WT. Flynn JR.,Heritability estimates versus large environmental
effects: the IQ paradox resolved.,Psychological Review. 108(2):346-69, 2001
Apr.
Abstract
Some argue that the high heritability of IQ renders purely environmental
explanations for large IQ differences between groups implausible. Yet, large
environmentally induced IQ gains between generations suggest an important
role for environment in shaping IQ. The authors present a formal model of
the process determining IQ in which people's IQs are affected by both
environment and genes, but in which their environments are matched to their
IQs. The authors show how such a model allows very large effects for
environment, even incorporating the highest estimates of heritability.
Besides resolving the paradox, the authors show that the model can account
for a number of other phenomena, some of which are anomalous when viewed
from the standard perspective. [References: 65]
Rafal
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