From The Economist print edition, Sep 23rd 2004, p. 95

New Evidence that people have been promiscuous for a long time.

LOTHARIOS everywhere will be pleased to hear that monogamy does not appear to be a natural human state. That, at least, is the conclusion of a study conducted by Michael Hammer at the University of Arizona in Tucson, and just published in Nature Genetics. By examining the DNA of living people, Dr Hammer and his colleagues have found that far fewer men than women pass their genes on to subsequent generations. In short, a small number of men have been putting it about a lot, thus outcompeting their lesser rivals.

The researchers draw their conclusion from differences between the variability of mitochondrial DNA (a type of DNA which follows the female line) and Y-chromosome DNA (which follows the male line). They examined the mitochondrial and Y-chromosome DNA of three widely separated populations