Cads and dads

RECEIVED wisdom and biological theory both have it that males are (or, at least, would like to be) more promiscuous than females. That does not stop a lot of men settling down happily as faithful husbands. Conversely, wisdom and theory also suggest that once a woman has kissed the frog who turns into a prince, she will stick with him till death do them part. But that is belied by the number of females who wander from man to man, or simply do without a helpmeet altogether.

As with many biological phenomena—height, for example—propensity for promiscuity in either sex might be expected to be normally distributed; that is, to follow what are known colloquially as “bell curves”. The peaks of these curves would have different values between the sexes, just as they do in the case of height. But the curves’ shapes would be similar.

Rafael Wlodarski of Oxford University wondered whether things are a little more complicated than that. Perhaps, he and his colleagues posit in a study just published in Biology Letters, rather than cads, dads and their female equivalents simply being at the extremes of a continuous distribution, individual people are specialised for these roles. If so, the curve for each sex would look less like the cross-section of a bell, and more like that of a Bactrian camel, with two humps instead of one.