In an astonishing study recently undertaken in western Europe, the following facts emerged : married females choose to have affairs with males who are dominant, older, more physically attractive, more symmetrical in appearance and married; females are much more likely to have an affair if their mates are subordinate, younger, physically unattractive or have asymmetrical features; cosmetic surgery to improve male's looks doubles his chance of having an adulterous affair; the more attractive a male is the less attentive he is as a father; roughly one in three of the babies born in western Europe is the product of an adulterous affair. If you find these facts disturbing or hard to believe, worry not. The study was not done on human beings at all. It refers entirely to swallows, the innocent, twittering, fork-tailed birds that pirouette prettily around barns and fields in the summer months. Human beings are entirely different from swallows. Or are they?
-- Matt Ridley