The Ape That Thought It Was a Peacock: Does Evolutionary Psychology Exaggerate Human Sex Differences?
Steve Stewart-Williams and Andrew G. Thomas
This article looks at the evolution of sex differences in sexuality in human beings and asks whether evolutionary psychology sometimes exaggerates these differences. According to a common understanding of sexual selection theory, females in most species invest more than males in their offspring, and as a result, males compete for as many mates as possible, whereas females choose from among the competing males. The males-compete/females-choose (MCFC) model applies to many species but is misleading when applied to human beings. This is because males in our species commonly contribute to the rearing of the young, which reduces the sex difference in parental investment. Consequently, sex differences in our species are relatively modest. Rather than males competing and females choosing, humans have a system of mutual courtship: Both sexes are choosy about long-term mates, and both sexes compete for desirable mates. We call this the mutual mate choice (MMC) model. Although much of the evolutionary psychology literature is consistent with the MMC model, the traditional MCFC model exerts a strong influence on the field, distorting the emerging picture of the evolved sexual psychology of Homo sapiens. Specifically, it has led to the exaggeration of the magnitude of human sex differences, an overemphasis on men’s short-term mating inclinations, and a relative neglect of male mate choice and female mate competition. We advocate a stronger focus on the MMC model.