Agence France-Presse

PARIS — Men significantly outnumbered women in the “out-of-Africa” migration some 60,000 years ago that eventually populated the rest of the world, according to a new study.

Africa is known to be the cradle of human evolution, and recent studies show that the people inhabiting other continents originate from a relatively small band of Homo sapiens who moved through the Near East, into Europe and beyond some 50,000 and 70,000 years ago.

But until now no one had figured out a way to determine what the sex-ratio of this so-called founding population might have been.

A quartet of researchers led by Alon Keinan at the Harvard Medical School thought that the secret might be locked inside differences in genetic code across distinct geographic regions.

They knew that the percentage of X chromosomes in a given population varies depending on the proportion of men.

The “X” and “Y” chromosomes determine sex — men have one of each, while women have two X chromosomes. The other 22 chromosome pairings in the human genome are all the same.

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