Wednesday, October 27, 2010

How/why did selection for lactase persistence occur and spread?

Interesting, albeit speculative, hypothesis for the origins of the selective advantage associated with lactase persistence. Basically, looks like there is evidence for increased reliance on milk products and dairy animals at the same time as a sudden cold and dry spell - about 8,000 years ago.
Link to new story in Science

...on a related note, see a post by Razib pointing to a story about "How Middle Eastern Milk Drinkers Conquered Europe".


Maju said...

I think that there's a fundamental error in the molecular clock hunching methods and that the alleles are older and spread randomly (founder effect) not by any selective reason. Maybe after that it was mildly selected in some areas where pastoralism was more intense but the pattern of distribution does not seems to correlate strongly with Neolithic or anything that makes sense.

Unless Magdalenian people were already milking horses... who knows?

Henry Harpending said...

It seems pretty obvious why it spread when one computes the Calorics. A liter of cow milk has 720 calories, 270 of which are lactose. So a kid gets 450 Calories from that liter if he is not LP, 720 Calories if he is.

This would make a big big difference if there were hunger.

Henry Harpending

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