Rape of women by men might be generated either by a specialized rape adaptation or as a by-product of other psychological adaptations. Although increasing number of sexual partners is a proposed benefit of rape according to the “rape as an adaptation” and the “rape as a by-product” hypotheses, neither hypothesis addresses directly why some men rape their long-term partners, to whom they already have sexual access. In two studies we tested specific hypotheses derived from the general hypothesis that sexual coercion (...) in the context of an intimate relationship may function as a sperm competition tactic. We hypothesized that men’s sexual coercion in the context of an intimate relationship is related positively to his partner’s perceived infidelities and that men’s sexual coercion is related positively to their mate retention behaviors (behaviors designed to prevent a partner’s infidelity). The results from Study 1 (self-reports from 246 men) and Study 2 (partner-reports from 276 women) supported the hypotheses. The Discussion section addresses limitations of this research and highlights future directions for research on sexual coercion in intimate relationships. (shrink)

Conspecific violence has been pervasive throughout evolutionary history. The current research tested the hypotheses that individuals implicitly categorize combative contexts (i.e., play fighting, status contests, warfare, and anti-exploitative violence) and use the associated contextual information to guide expectations of combative tactics. Using U.S. and non-U.S. samples, Study 1 demonstrated consistent classification of combative contexts from scenarios for which little information was given and predictable shifts in the acceptability of combative tactics across contexts. Whereas severe tactics (e.g., eye-gouging) were acceptable in (...) warfare and anti-exploitative violence, they were unacceptable in status contests and play fights. These results suggest the existence of implicit rules governing the contexts of combat. In Study 2, we explored the reputational consequences of violating these implicit rules. Results suggest that rule violators (e.g., those who use severe tactics in a status contest) are given less respect. These are the first studies to implicate specialized mechanisms for aggression that use contextual cues of violence to guide expectations and behavior. (shrink)

Cuckoldry is an adaptive problem faced by parentally investing males of socially monogamous species (e.g., humans and many avian species). Mate guarding and frequent in-pair copulation (IPC) may have evolved as anti-cuckoldry tactics in avian species and in humans. In some avian species, the tactics are used concurrently, with the result that mate guarding behaviors and IPC frequency are correlated positively. In other avian species, the tactics are compensatory, with the result that mate guarding behaviors and IPC frequency are correlated (...) negatively. The relationship between mate guarding and IPC frequency in humans is unknown. Avian males that use these tactics concurrently share with human males an inability to guard a female partner continuously during her peak fertile period. We hypothesized, therefore, that men’s mate guarding and IPC frequency function as concurrent anti-cuckoldry tactics, resulting in a positive correlation between them. Study 1 (n=305) secured men’s self-reports of mate guarding and IPC frequency. Study 2 (n+367) secured women’s reports of their partners’ mate guarding and IPC frequency. The concurrent tactics hypothesis was supported in both studies: Men’s mate guarding and IPC frequency are correlated positively, and this association is not attributable to male age, female age, relationship satisfaction, relationship length, or time that the couple spends together. The Discussion section addresses potential limitations of this research and future research directions. (shrink)

Schmitt recognized that research is needed to identify other factors associated with sex ratio and with sociosexuality that may explain cross-cultural variation in sexual behavior. One such factor may be the risk of sperm competition. Sperm competition theory may lead us to a more complete explanation of cultural variation in sexual behavior.