Evolution of large brains (was Online Paper)

From: Keith Henson (hkhenson@rogers.com)
Date: Wed 29 Oct 2003 - 14:27:26 GMT

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    At 09:11 AM 29/10/03 +0000, you wrote:
    > > This seems to be true for Y, but I don't think it
    > > can be shown to be the
    > > case for the rest of the genome.
    >
    >But it does seem to be true for at least those other
    >parts of the genome that have been sufficiently well
    >analysed, eg.
    >
    >http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8640220&dopt=Abstract
    >
    >Anyway, let's suppose that that there is some truth in
    >the regional continuity hypothesis and that modern
    >non-African populations do have some steppe erectus or
    >neanderthal genes in them. I still don't see how
    >evolutionary pressures on northern erectus populations
    >can have had much effect on modern human brains as a
    >whole. You could postulate that non-African brains
    >are in some way different to the brains of Africans,
    >but surely that is not what Calvin is arguing....?

    He is arguing just that. Namely that genes for large brains were selected by stresses and opportunities at the edge of the human range as the glaciers came and went many times.

    >The only other alternative would be that the changes
    >in erectus brains that happened on the Eurasian
    >steppes somehow, by gene flow or back-migration into
    >Africa, got incorporated in African brains too.

    Not an alternative, part of the same picture.

    >Of course, as I said, I haven't actually read the
    >book, so perhaps I have the wrong end of the stick entirely......

    It not a long book, reads fast, and it is all here

    http://williamcalvin.com/bk5/bk5.htm

    Keith Henson

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