McKibbin, W. F., Starratt, V. G., Shackelford, T. K., & Goetz, A. T. (2011). Perceived risk of female infidelity moderates the relationship between objective risk of female infidelity and sexual coercion in Humans (Homo sapiens). Journal of Comparative Psychology, 125, 370-373.

Perceived Risk of Female Infidelity Moderates the Relationship Between Objective Risk of Female Infidelity and Sexual Coercion in Humans (Homo sapiens)

William F. McKibbin, Valerie G. Starratt, Todd K. Shackelford, and Aaron T. Goetz

 

Female extrapair copulation (EPC) can be costly to a woman’s long-term romantic partner. If a woman has copulated recently with a man other than her long-term partner, her reproductive tract may contain the sperm of both men, initiating sperm competition (whereby sperm from multiple males compete to fertilize an egg). Should the woman become pregnant, her long-term partner is at risk of cuckoldry—investing unwittingly in offspring to whom he is not genetically related. Previous research in humans (Homo sapiens) and in nonhuman animals suggests that males have evolved tactics such as partner-directed sexual coercion that reduce the risk of cuckoldry. The current research provides preliminary evidence that mated men (n  223) at greater risk of partner EPC, measured as having spent a greater proportion of time apart from their partner since the couple’s last in-pair copulation, more frequently perform partner-directed sexually coercive behaviors. This relationship is moderated, however, by men’s perceived risk of partner EPC, such that the correlation between the proportion of time spent apart since last in-pair copulation and sexually coercive behaviors remains significant only for those men who perceive themselves to be at some risk of partner EPC. Discussion addresses limitations of this research and highlights directions for future research investigating the relationship between female EPC and men’s partner-directed sexual coercion.

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McKibbin, W.F., Bates, V.M., Shackelford, T.K., Hafen, C.A., & LaMunyon, C.W. (2010). Risk of sperm competition moderates the relationship between men’s satisfaction with their partner and men’s interest in their partner’s copulatory orgasm. Personality and Individual Differences, 49, 961-966

Risk of sperm competition moderates the relationship between men’s satisfaction with their partner and men’s interest in their partner’s copulatory orgasm

William F. McKibbin, Vincent M. Bates, Todd K. Shackelford,
Christopher A. Hafen, and Craig W. LaMunyon

 

Sperm competition occurs when the sperm of multiple males concurrently occupy a female’s reproductive
tract and compete for fertilization. Sperm competition may have been a recurrent adaptive problem over human evolutionary history (Shackelford & Pound, 2006). Women’s orgasm may facilitate selective uptake and retention of a particular man’s sperm (Thornhill & Gangestad, 2008). Men who are more satisfied with and invested in their relationship may experience greater costs in the event of sperm competition and potential cuckoldry. Therefore, these men may be especially interested in ensuring their partner’s copulatory orgasm. We hypothesized that men’s relationship satisfaction and investment would predict interest in their partner’s copulatory orgasm, and that sperm competition risk would moderate the association between relationship satisfaction and interest in partner’s copulatory orgasm. Using structural equation modeling on self-report data secured from 229 men in a committed heterosexual relationship, we tested and found support for these hypotheses.

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Goetz, A. T., Shackelford, T. K., Platek, S. M., Starratt, V. G., & McKibbin, W. F., (2007). Sperm competition in humans: Implications for male sexual psychology, physiology, anatomy, and behavior. Annual Review of Sex Research, 18, 1-22.

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

Aaron T. Goetz, California State University – Fullerton
Todd K. Shackelford, Florida Atlantic University
Steven M. Platek, University of Liverpool, UK
Valerie G. Starratt, Florida Atlantic University
William F. McKibbin, Florida Atlantic University

 

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.

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Shackelford, T. K., Goetz, A. T., McKibbin, W. F., & Starratt, V. G. (2007). Absence makes the adaptations grow fonder: Proportion of time apart from partner, male sexual psychology, and sperm competition in humans. Journal of Comparative Psychology, 121, 214-220.

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

Todd K. Shackelford, Aaron T. Goetz, William F. McKibbin, and Valerie G. Starratt

Florida Atlantic University

 

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 couple’s last copulation reported (a) greater sexual interest in his partner, (b) greater
distress in response to his partner’s sexual rejection, and (c) greater sexual persistence in response to his
partner’s sexual rejection. All effects were independent of total time since the couple’s last copulation
and the man’s relationship satisfaction. Discussion addresses limitations of the current research and
situates the current results within the broader comparative literature on adaptation to sperm competition.

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Starratt, V. G., Shackelford, T. K., Goetz, A. T., & McKibbin, W. F., (2007). Male mate retention behaviors vary with risk of sperm competition. Acta Psychologica Sinica, 39, 523-527

Male mate retention behaviors vary with risk of sperm competition.

Valerie G. Starratt, Todd K. Shackelford, Aaron T. Goetz, and William F. McKibbin

Florida Atlantic University

 

Sperm competition occurs when the sperm of two or more males concurrently occupy the reproductive tract of a single female and compete to fertilize an egg. This can be costly if the woman’s social partner loses the competition and, as a consequence, invests in offspring that are not genetically his own, a situation known as cuckoldry. Previous research suggests that men may have evolved tactics such as mate retention behaviors that reduce the risk of sperm competition and cuckoldry. The current research provides new evidence that men at greater risk of partner infidelity and sperm competition, measured as having spent a greater proportion of time apart from their partner since the couple’s last in-pair copulation, more frequently perform a variety of mate retention behaviors, such as calling unexpectedly to check up on their partners, monopolizing their partners’ time when around other men, and threatening other men who show an interest in their partners

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