Re: Brain size, IQ

Len Piotrowski (
Mon, 26 Aug 1996 18:00:06 GMT

In article <4vqusf$> (Bryant) writes:


>As Dawkins points out in his _Extended Phenotype_, the association of
>larger cranial capacity and apparently increased intelligence in the Homo
>lineage suggests (demands) heritability for brain size in past human and
>proto-human populations. This is, hopefully, not controversial.

I am not familiar with Dawkin's hypothesis, but you would be mistaken about
the uncontroversialness of your statement. I'm surprised you haven't heard
about Gould's developmental hypothesis and it's (non-functional,
non-adaptionist) effects upon head/body ratios.

>But considerable controversy has surrounded the suggestion that this is
>still true--that human IQ is still heritable, and that it is related to
>gross brain size. One problem for those who would propose a simplistic
>brain size/IQ (causal) relationship is that white women's smaller brains
>score higher, on average, than black men's larger brains during IQ tests.

The evolutionary significance of altered developmental ratios for humans,
seems to affect the sexes differently. Females appear to experience prolonged
developmental growth with respect to males, thus apparently increasing the
time and development of the neural net. A byproduct of this developmental
retardation may just be something measurable by the human IQ test. Who knows?

>[snipped - sociobiological IQ argument?]

... if so, so what?