September 27th, 2008

breaking bad

A recent study in genetic variance

andyduckerlinks links to this new scientist study. I read about this research somewhere else over the summer (wish I could remember where) and I was thinking about it a lot while I was in Brittany. The basic research as I understand it shows that there is twice as much variance in the DNA we have inherited from female ancestors as from male (this x2 figure isn't given in the linked article, sorry I can't find the reference). But in any case, roughly, we have twice as many female ancestors as male ancestors.

The way the male scientists report this is 'Some men mated with lots of women', which is one way of putting it. Another way of putting it is that for an extended period in prehistory men were twice as likely as women to die without reproducing themselves. And when you consider how dangerous it must have been for women to give birth in a cave, this means that men must have been dying at a rate we don't see in any population these days: more than 50% of men must have died without any offspring at all. If you think that more that two thirds of the men and women alive in the Middle Ages have offspring alive today (despite the black death etc.) then you can see that there must have been a male-skewed die-off quite unlike anything in recorded history.
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