Cultural assumptions are a powerful thing. In the Descent of Man, Charles Darwin, reflecting on the colorful and oversized tails of male peacocks, suggested that males gain evolutionary advantage by mating frequently and indiscriminately, while choosy females do not. To test this hypothesis, Angus Bateman, an English geneticist, ran a series of experiments on the mating behavior of fruit flies. His landmark study, published in 1948, found the hypothesized asymmetry. Extrapolating to all sexually reproducing animals, Bateman concluded that whereas female reproductive success (that is, number of viable offspring) peaks with a single male, male success increases with competition and sexual profligacy.