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December 09, 2002

Another one joining the legions of darkness?

I'm taking a small break from my development project, so I was kicking back with the book A Brain For All Seasons: Human Evolution & Abrupt Climate Change by William Calvin. I've read many of his other books and didn't find him to be particularly controversial. But I stumbled upon this on page 41:

...There is far more variation within modern African Homo Sapiens than there is within the Out of Africa groups. Modern Africans really need the variation in reserve, just to work around the challenges from their parasite load and their fickle climate. The Asians and Europeans, besides being less rich in genetic variations that they can tap, seem to have specialized somewhat toward one end of the parental-care spectrum, concentrating on relatively fewer offspring (their biology results in having fewer fraternal twins) who grow up more slowly (somewhat slower growth rates, later puberty, and so forth).

More on page 61:

You see a lot of assumptions about bigger brains having been important for colonizing Eurasia with its wintertime challenges, but that's simplistic. I certainly suspect that the different environments of Eurasia caused some variants among the African immigrants to thrive better than others (and planning ability is often needed to get through the winter), and I'm quite willing to assume that the somewhat bigger brains came along with a package, but I'd really like to know what that package is.

Posted by razib at 12:26 PM