William F. McKibbin

Why do men rape? An evolutionary psychological perspective.

Rape of women by men has occurred throughout recorded history and across cultures. In this article, we discuss rape from an evolutionary psychological perspective. Evolutionary psychology is a powerful heuristic tool that allows researchers to develop and test novel hypotheses about complex behaviors such as rape. Some researchers have argued that men have evolved psychological mechanisms that motivate them to rape in specific contexts. We discuss evidence consistent with this claim, and argue that a more nuanced view of mens rape behavior is necessary. We propose that it may be useful to characterize rapists as belonging to one of several types, distinguished by individual differences as well as by the circumstances in which they are predicted to commit rape. We discuss research evidence in support of each rapist type, as well as the need for future research. Finally, we discuss research concerning womens rape-avoidance psychology and behavior.

Absence Makes the Adaptations Grow Fonder: Proportion of Time Apart From Partner, Male Sexual Psychology, and Sperm Competition in Humans (Homo sapiens)

Sperm competition occurs when the sperm of multiple males concurrently occupy the reproductive tract of a female and compete to fertilize an egg. We used a questionnaire to investigate psychological responses to the risk of sperm competition for 237 men in committed, sexual relationships. As predicted, a man who spends a greater (relative to a man who spends a lesser) proportion of time apart from his partner since the couples last copulation reported (a) greater sexual interest in his partner, (b) greater distress in response to his partners sexual rejection, and (c) greater sexual persistence in response to his partners sexual rejection. All effects were independent of total time since the couples last copulation and the mans relationship satisfaction. Discussion addresses limitations of the current research and situates the current results within the broader comparative literature on adaptation to sperm competition.

Men’s Partner-Directed Insults and Sexual Coercion in Intimate Relationships

Women who have been sexually coerced by an intimate partner experience many negative health consequences. Recent research has focused on predicting this sexual coercion. In two studies, we investigated the relationship between men’s use of partner-directed insults and sexually coercive behaviors in the context of intimate relationships. Study 1 secured self-reports from 247 men on the Partner-Directed Insults Scale and the Sexual Coercion in Intimate Relationships Scale. Study 2 obtained partner-reports from 378 women on the same measures. Across both studies, results indicate that men’s use of sexually coercive behaviors can be statistically predicted by the frequency and content of the insults that men direct at their intimate partner. Insults derogating a partner’s value as a person and accusing a partner of sexual infidelity were most useful in predicting sexual coercion. The discussion notes limitations of the current research and highlights directions for future research.

Sperm Competition in Humans: Implications for Male Sexual Psychology, Physiology, Anatomy, and Behavior

Abstract With the recognition afforded by evolutionary science that female infidelity was a recurrent feature of our evolutionary past has come the development of a new area of study within human mating: sperm competition. A form of male-male postcopulatory competition, sperm competition occurs when the sperm of two or more males concurrently occupy the reproductive tract of a female and compete to fertilize her ova. Just as males must compete for mates, if two or more males have copulated with a female within a sufficiently short period of time, the sperm from different males will compete for fertilizations. In the 2 decades since Smith (1984) first argued that sperm competition occurs in humans, this theory has been enriched with new ideas and discoveries. We review the recent theoretical and empirical work on human sperm competition, identify limitations and challenges of the research, and highlight important directions for future research.