As female primates carry and nurse the fetus, it naturally falls on them to rear the o¤spring. On the assumption that males are at least equally adept at obtaining food, it follows that they generate a surplus which they might either share with females or consume themselves. This choice lies at the heart of an evolutionary battle of the sexes. If females suceed in obtaining a large share of the surplus, there is little scope for size dimorphism between males and females; otherwise males can use the surplus to sustain larger and stronger bodies, which are advantageous in sexual competition with other males. Besides competing with males, females may compete with each other. Moreover, dependency may coincide with sexiness and such dependency can persist. This paper examines these ideas in a game-theoretic setting