Abstract
Growing interest in sexual conflict since the late 1980s reflects several developments within behavioral ecology. These include recognition of females as active participants in co-evolutionary interactions,1-3 demonstrations of high levels of extrapaternity in many “monogamous” species,4 remarkable evidence of life-threatening toxic compounds in the sperm of fruit flies,5 and experimental studies revealing deleterious consequences of arms races for both males and females.6 Many of the ideas in this new body of work were sparked by Parker's papers on how sexual conflict shapes physiological and behavioral traits. These ideas were brought to popular attention by Dawkins,7:140 who posed the question: “If there is conflict of interests between parents and children, who share 50% of each others' genes, how much more severe must be the conflict between mates, who are not related to each other?” Research into sexual conflict among nonhuman primates is flourishing,8 but has received less explicit attention in the study of humans, despite cogent arguments that women's strategies are often constrained by the forceful and manipulative behavior of men and their kin.3, 9 Here we explore new hypotheses for the extent and direction of sexual conflict among humans, both within and between populations, focusing on signaling mate quality, family size preferences, and the marital bond.