Promiscuity

is so widely known it is almost a cliché, despite continually being misunderstood. His concept of sexual selection is less well known but no less important. Darwin developed the idea of sexual selection to account for the dramatic differences that often exist in the appearance and behavior of the sexes. The reason for these differences, he said, was competition for, or choice of, sexual partners. Typically, males compete among themselves for females, hence their larger body size and their weapons, such as antlers and spurs. Females, on the other hand, typically choose among males on the basis of the males’ elaborate coloration, extravagant ornaments, or remarkable vocal repertoires. One integral aspect of Darwin’s concept of sexual selection was male promiscuity–the fact that, in many animals, males achieve high reproductive success by copulating with several different females. At the same time as he accepted male promiscuity as the norm and as an important component of sexual selection, Darwin regarded females as sexually monogamous and faithful to a partner for at least a single breeding attempt. By doing so he automatically assumed that sexual selection ceased once an individual of either sex had acquired a mating partner. But Darwin knew it wasn’t true that females were sexually monogamous, for in his various writings he referred to instances in which females had received sperm from more than one male. For example, in The Descent of Man, and Selection in Relation to Sex (1871), Darwin refers to a case his cousin William Darwin Fox recounted to him, of a female domestic goose that copulated with both a male domestic goose and a Chinese goose and hatched a brood of very obvious mixed paternity. Despite such clear evidence to the contrary, though, Charles Darwin stuck 1⁄2rmly to the story of female monogamy. There are several reasons for this. First, although it was perfectly respectable to discuss sexuality, fertilization, and promiscuity among plants, it was