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From:
Subject: Re: [DNA] Brown eyes
Date: Tue, 9 May 2006 00:03:59 EDT


In a message dated 05/08/06 1:45:25 PM Pacific Daylight Time,
writes:

> I am not interested in prolonging these word games; there would be a
> practical application I am interested in in population studies (and
> potentially rate of selection against the brown gene) if the data of brown
> eye percentages by regional populations (much like the existing blood group
> data) exists, but so far that has eluded searches and perhaps does not
> exist.

If you're interested in natural (or sexual) selection, which acts on the
phenotype, not the genotype, why does it matter so much to you that there be just
one allele for one gene that results in brown eye color? Selection acts on
many multi-factorial traits.

Anyway, I checked Cavalli-Sforza's "History and Geography of Human Genes." He
covers eye color briefly, but he does include a map taken from Carleton
Stevens Coon "The Races of Europe" for hair / eye color combined (in quintiles of
light to dark). The general impression is clines with a few localized "islands"
that darker or lighter than their surrounding neighbors. I have the big
hard-cover edition, but I think the paperback version would have the same text and
pictures (pp 266-267 if someone wants to check for Ken).

The bibliography says Coon's book was published in 1954; however, when I
check various used book sites and the Library of Congress, the only dates I see
are for the first edition (1939) and a reprint (1972). It's possible that Coon's
book has more raw data -- it's over 700 pages -- but the title of his book
may hint at the reason the raw data is hard to find.

Cavalli-Sforza explains why he bypassed eye color in his monumental study:
"Unfortunately, the contribution of sexual selection is difficult to test,
preferences are characteristically unstable, and very sensitive to frequency of
types in the populations."

Ann Turner

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