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Hayakawa S, Kaguyama A. Evolution of male-to-female oral sex as a detection tool of bacterial vaginosis and subsequent infertility. Med Hypotheses 2022. [DOI: 10.1016/j.mehy.2022.110985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Pham MN, Barbaro N, Holub AM, Holden CJ, Mogilski JK, Lopes GS, Nicolas SCA, Sela Y, Shackelford TK, Zeigler-Hill V, Welling LLM. Do Men Produce Higher Quality Ejaculates When Primed With Thoughts of Partner Infidelity? EVOLUTIONARY PSYCHOLOGY 2018; 16:1474704918757551. [PMID: 29478337 PMCID: PMC10367497 DOI: 10.1177/1474704918757551] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 01/14/2018] [Indexed: 11/16/2022] Open
Abstract
Sperm competition theory can be used to generate the hypothesis that men alter the quality of their ejaculates as a function of sperm competition risk. Using a repeated measures experimental design, we investigated whether men produce a higher quality ejaculate when primed with cues to sperm competition (i.e., imagined partner infidelity) relative to a control prime. Men ( n = 45) submitted two masturbatory ejaculates-one ejaculate sample for each condition (i.e., sperm competition and control conditions). Ejaculates were assessed on 17 clinical parameters. The results did not support the hypothesis: Men did not produce higher quality ejaculates in the sperm competition condition relative to the control condition. Despite the null results of the current research, there is evidence for psychological and physiological adaptations to sperm competition in humans. We discuss methodological limitations that may have produced the null results and present methodological suggestions for research on human sperm competition.
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Affiliation(s)
| | | | | | | | | | | | | | - Yael Sela
- Oakland University, Rochester, MI, USA
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DeLecce T, Barbaro N, Mohamedally D, Shackelford TK. Husband's Reaction to His Wife's Sexual Rejection Is Predicted by the Time She Spends With Her Male Friends but Not Her Male Coworkers. EVOLUTIONARY PSYCHOLOGY 2017; 15:1474704917705062. [PMID: 28420246 PMCID: PMC10480843 DOI: 10.1177/1474704917705062] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2017] [Accepted: 03/25/2017] [Indexed: 11/15/2022] Open
Abstract
Males among many species, including humans, evaluate cues of sperm competition risk and adjust accordingly their sperm competition tactics. The number of potential sexual rivals can serve as an index of sperm competition risk. Therefore, men may adjust their in-pair copulatory interest in accordance with the presence of sexual rivals. Using self-reports from 45 married men, we test the hypotheses that the time a man's wife spends with other men-either male friends or male coworkers-will positively predict a man's copulatory interest in his wife (Hypothesis 1) and his anger (Hypothesis 2), upset (Hypothesis 3), and frustration (Hypothesis 4) in response to his wife's sexual rejection. The results show that the time wives spend with male friends (but not male coworkers) predicts their husbands' anger, upset, and frustration in response to sexual rejection, providing support for Hypotheses 2-4. Discussion highlights novel contributions of the current research and provides a potential explanation for the discrepant findings regarding male friends versus male coworkers.
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Affiliation(s)
- Tara DeLecce
- College of Liberal Arts and Sciences, Wayne State University, Detroit, MI, USA
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Pham MN, DeLecce T, Shackelford TK. Sperm competition in marriage: Semen displacement, male rivals, and spousal discrepancy in sexual interest. PERSONALITY AND INDIVIDUAL DIFFERENCES 2017. [DOI: 10.1016/j.paid.2016.09.056] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Pham MN, Jeffery AJ, Sela Y, Lynn JT, Trevino S, Willockx Z, Tratner A, Itchue P, Shackelford TK, Fink B, McDonald MM. Duration of Cunnilingus Predicts Estimated Ejaculate Volume in Humans: a Content Analysis of Pornography. EVOLUTIONARY PSYCHOLOGICAL SCIENCE 2016. [DOI: 10.1007/s40806-016-0057-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Jeffery AJ, Pham MN, Shackelford TK, Fink B. Does human ejaculate quality relate to phenotypic traits? Am J Hum Biol 2015; 28:318-29. [PMID: 26626022 DOI: 10.1002/ajhb.22805] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 10/08/2015] [Accepted: 10/27/2015] [Indexed: 11/06/2022] Open
Abstract
A given man's phenotype embodies cues of his ancestral ability to effectively defend himself and his kin from harm, to survive adverse conditions, and to acquire status and mating opportunities. In this review, we explore the hypothesis that a man's phenotype also embodies cues to fertility or the probability that an ejaculate will fertilize ova. Female mate choice depends on the ability to discern the quality of a male reproductive partner through his phenotype, and male fertility may be among the traits that females have evolved to detect. A female who selects as mates males that deliver higher quality ejaculates will, on average, be more fecund than her competitors. Data on several non-human species demonstrate correlations between ejaculate quality and secondary sexual characteristics that inform female mate choice, suggesting that females may select mates in part on the basis of fertility. While the non-human literature on this topic has advanced, the human literature remains limited in scope and there is no clear consensus on appropriate methodologies or theoretical positions. We provide a comprehensive review and meta-analysis of this literature, and conclude by proposing solutions to the many issues that impede progress in the field. In the process, we hope to encourage interest and insight from investigators in other areas of human mating and reproductive biology. Am. J. Hum. Biol. 28:318-329, 2016. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
| | - Michael N Pham
- Department of Psychology, Oakland University, Rochester, Michigan, 48307
| | - Todd K Shackelford
- Department of Psychology, Oakland University, Rochester, Michigan, 48307
| | - Bernhard Fink
- Institute of Psychology and Courant Research Center Evolution of Social Behavior, University of Göttingen, Göttingen, Germany
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Barbaro N, Pham MN, Shackelford TK. Sperm Competition Risk and Sexual Coercion Predict Copulatory Duration in Humans. EVOLUTIONARY PSYCHOLOGY 2015; 13:1474704915618411. [PMID: 37924196 PMCID: PMC10481053 DOI: 10.1177/1474704915618411] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 10/28/2015] [Indexed: 11/06/2023] Open
Abstract
A man whose romantic partner is sexually unfaithful is at risk of sperm competition and cuckoldry-unwitting investment in offspring to whom he is genetically unrelated. Men, therefore, may have evolved mechanisms to solve the adaptive problems of sperm competition and cuckoldry. The current research investigates another potential anti-cuckoldry tactic: reducing in-pair copulation (IPC) duration, thereby more quickly placing his sperm into competition. We hypothesize that IPC duration will be negatively correlated with female infidelity (Hypothesis 1). We further hypothesize that IPC duration will be negatively correlated with sexual coercion (Hypothesis 2). Results of Study 1 (men's reports, n = 410) indicate that both men's perceptions of female infidelity and men's sexual coercion predict shorter IPC duration. Results of Study 2 (women's reports, n = 455) did not provide statistical support for the study hypotheses. The current research provides an initial investigation of men's adjustment of copulatory duration and suggests that men reduce IPC duration and ejaculate more quickly at the couple's most recent copulation, in response to greater risk of sperm competition and in the context of sexual coercion.
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Affiliation(s)
- Nicole Barbaro
- Department of Psychology, Oakland University, Rochester, MI, USA
| | - Michael N. Pham
- Department of Psychology, Oakland University, Rochester, MI, USA
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Development and Initial Validation of the Coalitional Mate Retention Inventory. EVOLUTIONARY PSYCHOLOGICAL SCIENCE 2014. [DOI: 10.1007/s40806-014-0001-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Pham MN, Shackelford TK, Welling LLM, Ehrke AD, Sela Y, Goetz AT. Oral Sex, Semen Displacement, and Sexual Arousal: Testing the Ejaculate Adjustment Hypothesis. EVOLUTIONARY PSYCHOLOGY 2013. [DOI: 10.1177/147470491301100515] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Male Indian Flying Foxes ( Pteropus giganteus) that spend more time performing oral sex on a female also spend more time copulating with her. In humans, men who spend more time copulating with their regular partner also perform more “semen-displacing” copulatory behaviors (e.g., deeper, more vigorous penile thrusting). We investigated whether men who spend more time performing oral sex on their regular partner also spend more time copulating with her and perform more semen-displacing copulatory behaviors. We proposed and tested the ejaculate adjustment hypothesis for men's copulatory behaviors: Men adjust their copulatory behaviors to increase their sexual arousal and consequent ejaculate quality, thereby increasing their chances of success in sperm competition. Two hundred and thirty-three men in a committed, heterosexual relationship responded to questions about their copulatory behavior and sexual arousal during their most recent sexual encounter with their long-term partner. The results indicated that men who spend more time performing oral sex on their partner also spend more time copulating with her, perform more semen-displacing copulatory behaviors, and report greater sexual arousal. We discuss limitations to the current research and highlight the heuristic value of sperm competition theory for understanding human sexual behaviors.
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Affiliation(s)
- Michael N. Pham
- Department of Psychology, Oakland University, Rochester, Michigan, USA
| | | | | | - Alyse D. Ehrke
- Department of Psychology, Oakland University, Rochester, Michigan, USA
| | - Yael Sela
- Department of Psychology, Oakland University, Rochester, Michigan, USA
| | - Aaron T. Goetz
- Department of Psychology, California State University Fullerton, Fullerton, California, USA
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