Thursday, November 9, 2017

An Evolutionary Perspective on Orgasm

Gallup, G. G., Jr., Towne, J. P., & Stolz, J. A. (2017). An Evolutionary Perspective on Orgasm. Evolutionary Behavioral Sciences, http://dx.doi.org/10.1037/ebs0000104

Abstract: The capacity to experience an orgasm evolved to promote high-frequency sex in species with low reproductive rates. Growing evidence shows that orgasms also have a variety of other reproductive consequences. Based on a distinction between orgasm frequency and orgasm intensity, there is emerging evidence in humans that orgasms function to promote and fine tune what are often very different, sex-specific reproductive outcomes. We provide an overview of the effect of hormonal contraceptives on orgasm, mate choice, and sexual satisfaction. The effects of sex during pregnancy, along with orgasm induced vocalizations, facial expressions during orgasm, and the putative effects of semen exposure on orgasm and sexual functioning in females are also discussed. Recent research suggests that female orgasms evolved to promote good mate choices, and we propose that instances of orgasmic dysfunction in many women may be a byproduct of an inability to find and/or retain high-quality male partners.

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Factor into this matrix evidence showing that women who engage in extrapair copulations are more likely to be in the fertile phase of their cycle, less likely to use contraception, and more likely to experience orgasm (Baker & Bellis, 1993), and it becomes apparent that females may have been shaped by their evolutionary history to use extrapair copulations to bare children sired by genetically superior males and/or to increase the range of genetic variation among their existing children (Gallup & Burch, 2006).  By the time a woman has had three children sired by the same man, she will have sampled roughly 87.5% of his genes, and therefore, any additional children sired by the same man will be increasingly redundant genetic samples (Gallup & Ampel, 2017). By targeting high-quality males for extrapair copulations women, can have children sired by genetically superior males and as an added bonus, children sired by different males represents a hedge against an uncertain future. Consistent with this analysis women are not only more likely to experience orgasm, they also report more intense orgasms as a result of extrapair copulations (Gallup, Burch, & Mitchell, 2006). Therefore, if you are a woman whether you experience an orgasm and who you experience an orgasm with may make an important difference. Moreover, it seems reasonable to suppose that variation in orgasm intensity ought to be proportional to the magnitude of the vaginal and intrauterine contractions that occur during orgasm, which puts a reproductive premium on orgasm intensity. Suffice it to say that for all of these reasons, Lloyd’s (2005) claimed that orgasm in women was not subject to natural selection is untenable.

In contrast to females, it has been suggested that variation in ratings of orgasm intensity among males is an index or proxy for sperm recruitment (Gallup et al., 2012). Gallup et al.  predicted that the ejaculate which accompanies more intense orgasms will contain more sperm and higher concentrations of other seminal chemicals tailored to make conception more likely. For example, recent research by Pham et al. (2016) shows that estimates of ejaculate volume as a measure of ejaculate quality, correlate with the duration of cunnilingus as a prelude to sexual intercourse. Because of a history of competition for paternity, coupled with the high costs of being cuckolded, we predict that indications of partner infidelity ought to also be conducive to the occurrence of more intense orgasms in men. In other words, while more intense female orgasms may function as a mate choice mechanism, more intense orgasms in men may be a reflection of sperm recruitment mechanisms that function to compete with the possibility of rival male semen in their partner’s reproductive tract. A seemingly counterintuitive but nonetheless testable prediction that follows from this analysis would be that males who fantasize about partner infidelity during sex or masturbation would be expected to experience more intense orgasms. The growing prevalence of websites on the Internet that cater to such male fantasies provides suggestive evidence for such an effect. Research by Joyal, Cossette, and Lapierre (2015), showing that a significant proportion of men fantasize about having sex with couples that they and their partner know as well as couples they do not, is also consistent with this hypothesis.

A corollary prediction would be that variation in the reproductive value of different female partners ought to be proportional to corresponding variation in male orgasm intensity.  This could be tested by partitioning variation in the appearance of females depicted in pornographic videos to see if the composition of semen samples taken from males who masturbate while watching such videos varies as a function of how they rate their orgasms and as a function of objective variation in different fitness indicators among female pornography stars such as waist to hip ratios, facial attractiveness, breast size, and so forth. Variations in most physical dimensions of interpersonal attraction and sex appeal are well-documented proxies for underlying differences in health and fertility (Gallup & Frederick, 2010).

Recently, Joseph, Sharma, Agarwal, and Sirot (2015) found that ejaculate quality (as indexed by parameters such as ejaculate volume and number of motile sperm) goes up when men are exposed to novel/unfamiliar women, and men ejaculate faster when shown a new woman following a series of repeated exposures to the same woman. Thus, not surprisingly, the Coolidge effect (for a review, see Dewsbury, 1981) appears to be accompanied by testicular adjustments that make for a higher quality ejaculate, and we predict that under such conditions, males will report corresponding increases in orgasm intensity as well.

It is interesting that there may even be an assortative mating/social comparison component to such testicular adjustments. Leivers, Rhodes, and Simmons (2014a) found an interaction between male mate value and female attractiveness for measures of ejaculate quality.  Men with high mate value (based on attractiveness, dominance and self-perceived mate value) only produced high-quality ejaculates when given the opportunity to view images of attractive females. Just the opposite was true for men of low mate value, who produced lower quality ejaculates when viewing attractive females.  Thus, there appears to be a context dependent effect on ejaculate quality that interacts with the mate value of the male and the attractiveness of the female. High-value males only allocate high-quality ejaculates to attractive females.  Also implicating the existence of specialized ejaculate allocation mechanisms based on tradeoff effects, Leivers, Rhodes, and Simmons (2014b) found that men who engage in fewer mate guarding behaviors produce higher quality ejaculates.

In the context of the social psychological properties of orgasm and intersexual reproductive competition, evidence shows that some women fake orgasms in an effort to promote partner retention (Kaighobadi, Shackelford, & Weekes-Shackelford, 2012). Consistent with these results implicating attempts by women to feign orgasms to manipulate their mates, Brewer and Hendrie (2011) found that rather than being triggered by orgasm, copulatory vocalizations by some women were more likely to occur during male ejaculation. Indeed, Ellsworth and Bailey (2013) found that faked orgasms were correlated with the likelihood that women had engaged in sexual infidelity. Ellsworth and Bailey also found that males were more sexually satisfied with females who experienced more intense and frequent orgasms, and therefore, they speculate that variation in female orgasms may convey information about the probability of paternity.

Do Orgasms Give Women Feedback About Mate Choice? Gordon G. Gallup et al. Evolutionary Psychology, 2014. 12(5): 957-977. https://www.researchgate.net/publication/308086891

Abstract: The current study represents a preliminary investigation of the extent to which
female orgasm functions to promote good mate choices. Based on a survey of heterosexual female college students in committed relationships, how often women experienced orgasm as a result of sexual intercourse was related to their partner’s family income, his selfconfidence, and how attractive he was. Orgasm intensity was also related to how attracted they were to their partners, how many times they had sex per week, and ratings of sexual satisfaction. Those with partners who their friends rated as more attractive also tended to have more intense orgasms. Orgasm frequency was highly correlated (r = .82) with orgasm intensity, and orgasm intensity was a marginally better predictor of sexual satisfaction than orgasm frequency. Sexual satisfaction was related to how physically attracted women were to their partner and the breadth of his shoulders. Women who began having sexual intercourse at earlier ages had more sex partners, experienced more orgasms, and were more sexually satisfied with their partners. We also identified an ensemble of partner psychological traits (motivation, intelligence, focus, and determination) that predicted how often women initiated sexual intercourse. Their partner’s sense of humor not only predicted his self-confidence and family income, but it also predicted women’s propensity to initiate sex, how often they had sex, and it enhanced their orgasm frequency in comparison with other partners.

Keywords: orgasm frequency, orgasm intensity, sexual satisfaction, female initiated
intercourse, precocial sexual experience, partner sense of humor

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