Human estrus: implications for relationship science

Let's just do it: sexual arousal's effects on attitudes regarding sexual consent

Misperception of others' sexual willingness or consent is widely considered to contribute to sexual coercion. Sexual arousal is commonly present among those in situations with potential to result in sexual assault. The current research tests the effects of sexual arousal on related attitudes: including those toward token resistance, assertive sexual strategies, and affirmative consent. Sexual arousal was primed through a narrative writing paradigm. Results indicate sexual arousal led all participants to be more likely to endorse belief in female token resistance, and led women to more strongly endorse men's assertive sexual strategies. Implications for research on sexual consent are discussed.

Investigating cycle shifts in women's clothing style and grooming

In contrast to some non-human primate species, human females do not show overt cues to fertility. Previous research argued that women still show systematic changes in their appearance across their ovulatory cycle to enhance their mating success when fertile. We report five studies investigating whether women's clothing style and grooming behaviour change across the ovulatory cycle. All studies were large (with N = 157 in Study 1, N = 109 in Study 2, N = 257 in Studies 3-5), longitudinal studies with four testing sessions per participant. They involved salivary hormone samples and luteinizing hormone tests to validate conception risk estimates. Across all studies, our results suggest no compelling evidence for cycle shifts in clothing style and grooming. Rather, two studies suggest effects in the opposite direction as hypothesized, as women wore more skin-revealing clothes when non-fertile. One study suggests small effects of wearing necklaces more and eyeglasses less often when fertile. However, these effects were not robust across all studies. Our results are in line with other recent null replications and suggest that, if existent, cues to fertility might be even more subtle than previously assumed. We discuss the need for testing competing theories that explain the evolution of concealed ovulation.

The Mating Psychology of Incels (Involuntary Celibates): Misfortunes, Misperceptions, and Misrepresentations

Mating represents a suite of fundamental adaptive problems for humans. Yet a community of men, called incels (involuntary celibates), forge their identity around their perceived inability to solve these problems. Many incels engage in misogynistic online hostility, and there are concerns about violence stemming from the community. Despite significant media speculation about the potential mating psychology of incels, this has yet to be formally investigated in the scientific literature. In the first formal investigation of incel mating psychology, we compared a sample (n = 151) of self-identified male incels with non-incel single males (n = 149). Findings revealed that incels have a lower sense of self-perceived mate-value and a greater external locus of control regarding their singlehood. Contrary to mainstream media narratives, incels also reported lower minimum standards for mate preferences than non-incels. Incels (and non-incel single men) significantly overestimated the importance of physical attractiveness and financial prospects to women, and underestimated the importance of intelligence, kindness, and humor. Furthermore, incels underestimated women's overall minimum mate preference standards. Our findings suggest that incels should be targeted for interventions to challenge cognitive distortions around female mate preferences. Implications for incels' mental health and misogynistic attitudes are discussed, as well as directions for future research.

The use and misuse of evolutionary psychology in online manosphere communities: The case of female mating strategies

While early evolutionary accounts of female sexuality insisted on coyness and monogamous tendencies, evidence from the field of primatology started challenging those assumptions in the 1970s. Decades later, there exist many competing and overlapping hypotheses stressing the potential fitness benefits of female short-term and extra-pair mating. Female mammals are now seen as enacting varied and flexible reproductive strategies. This is both a victory for science, with a better fit between theory and reality, and for feminism, with the downfall of narrow stereotypes about female sexuality. However, evolutionary hypotheses on female mating strategies are routinely invoked among the antifeminist online communities collectively known as 'the manosphere'. Based on extensive qualitative analysis of manosphere discourse, this study shows how these hypotheses are sometimes interpreted in misogynistic online spaces. Indeed, evolutionary scholars might be surprised to see sexist worldviews reinforced by the 'dual mating strategy' and 'sexy son' hypotheses, or by the latest research on the ovulatory cycle. The manosphere has its own version of evolutionary psychology, mingling cutting-edge scientific theories and hypotheses with personal narratives, sexual double standards and misogynistic beliefs. After analysing this phenomenon, this article suggests ways to mitigate it.

Predicting Mate Poaching Experiences from Personality Traits Using a Dyadic Analysis

Mate poaching is "behavior intended to attract someone who is already in a romantic relationship." We investigated actor and partner effects of the five-factor personality traits and the dark triad traits on several mate poaching experiences. We used actor-partner interdependence modeling with data secured from both members of 187 heterosexual married, cohabiting and dating couples from Croatia. In a round-robin design, each participant rated their own and their partner's personality traits, and their own poaching experiences. The results showed that men's lower agreeableness had the most consistent relationship with poaching experiences in both men (actor effects) and women (partner effects). The role of other personality traits from the five-factor model was limited to specific aspects of poaching. Regarding the dark triad traits, men's psychopathy and Machiavellianism were the most consistently related to poaching experiences in both men and women, whereas narcissism did not demonstrate a consistent actor or partner effect on poaching. The results showed that men's poaching is associated with their own personality traits, whereas women's poaching with their own and their partner's personality traits. We interpret the results in the context of life history theory and mate switching hypothesis.

The role of hormones in attraction and visual attention to facial masculinity

The current study investigated the ovulatory shift hypothesis, which suggests that women prefer more masculine traits when estradiol is high, and progesterone is low (E/P ratio). The current study used an eye tracking paradigm to measure women's visual attention to facial masculinity across the menstrual cycle. Estradiol (E) and progesterone (P) were collected to determine if salivary biomarkers were associated with visual attention to masculine faces in a short- and long-term mating context. Women (N = 81) provided saliva samples at three time points throughout their menstrual cycle and were asked to rate and view men's faces that had been manipulated to appear feminine and masculine. Overall, masculine faces were viewed longer compared to feminine faces and this was moderated by mating context, where women viewed masculine faces longer for a long-term relationship. There was not any evidence suggesting that E/P ratio was associated with preferences for facial masculinity, but there was evidence to suggest that hormones were associated with visual attention to men in general. In line with sexual strategies theory, there was evidence to suggest that mating context and facial masculinity are important in mate choice; however, there was no evidence to suggest that women's mate choice was associated with shifts across the menstrual cycle.

Sexual Desire of Women With Fast and Slow Life History Throughout the Ovulatory Cycle

Findings on female sexual motivation across the ovulatory cycle are mixed. Some studies have reported increased female sexual desire on fertile days or midway through the ovulatory cycle, whereas others have reported increased sexual desire on nonfertile days. We postulated and tested the hypothesis that the pattern of the cyclical change of female sexual desire is associated with women's life history. Female participants completed life-history measures and rated their levels of sexual desire on the survey day and reported the first day of their current and subsequent cycle, respectively (Study 1), or recorded their sexual desire throughout an entire cycle by submitting daily reports (Study 2). Results indicate that women with a fast life history experienced peak sexual desire midcycle, whereas women with a slow life history experienced two peaks of sexual desire midcycle and around their menses. These findings suggest that, consistent with the underlying life history, cyclically differential peaking of sexual desire may serve different reproductive functions.

Motivation of non-monogamous adults to engage in sex with their different partners

This study compared motivations of individuals in non-monogamous relationships to engage in sex with their different partners (n = 596, out of which 103 non-consensual non-monogamous, 135 polyamorous, 204 swinging, 154 in open relationships; women—38.8%, men—59.7%, other gender—1.5%; age range: from 18 to 65+ years; 86% of respondents between 25 and 54 years old; majority of the respondents are in a long-term relationship). The research aim was to identify whether there are differences in reasons to engage in sex with respondents’ primary versus secondary partners. Presented with 17 reasons to engage in sexual activity, the respondents rated the frequency with which they engage in sex for each reason with their different partners. Questions for 14 reasons to engage in sex were created based on the YSEX? questionnaire and three questions were created specifically for non-monogamous population. The three new questions addressed the desire for a specific type of sex (such as kink, fetish, etc.), desire to have sex with a partner of another gender than one’s primary partner, and desire to experience the thrill of the forbidden. The results indicated that there are significant differences in motivation to engage in sex with one’s primary versus secondary partner for most of the reasons. Additionally, this study investigated whether there are differences in motivation to engage in sex with different partners depending on the relationship arrangement. The data analysis shows that there are differences in reasons to engage in sex with one’s different partners between non-consensually and consensually non-monogamous groups. This research compliments existing body of research with new reasons to engage in sex, it demonstrates that non-monogamous people engage in sex with their different partners for different reasons and reveals that these may vary depending on the type of the relationship arrangement.

Men are not aware of and do not respond to their female partner's fertility status: Evidence from a dyadic diary study of 384 couples

Understanding how human mating psychology is affected by changes in female cyclic fertility is informative for comprehending the evolution of human reproductive behavior. Based on differential selection pressures between the sexes, men are assumed to have evolved adaptations to notice women's within-cycle cues to fertility and show corresponding mate retention tactics to secure access to their female partners when fertile. However, previous studies suffered from methodological shortcomings and yielded inconsistent results. In a large, preregistered online dyadic diary study (384 heterosexual couples), we found no compelling evidence that men notice women's fertility status (as potentially reflected in women's attractiveness, sexual desire, or wish for contact with others) or display mid-cycle increases in mate retention tactics (jealousy, attention, wish for contact or sexual desire towards female partners). These results extend our current understanding of the evolution of women's concealed ovulation and oestrus, and suggest that both might have evolved independently.

“Sax for Sex”: A Brief Narrative Review Exploring the Music-Sex Connect

Context:

The assertion that music has an impact on sexual performance is a popular one. However, music is seldom used in clinical settings for enhancement of sexual problems and little is known regarding its scientific proof.

Aim:

To explore available literature on: the interplay between sex and music in the human evolution; brain basis for music and sex; and studies using music to therapeutically enhance sexual performance.

Conclusions:

Evidence suggests an evolutionary basis for the relationship between music and sex. There is converging neurobiological understanding that posits both music and sex to have common brain substrates—the reward pathway, diencephalic structures, limbic system, and prefrontal cortex. Psychological mechanisms hypothesized for a positive role of music in enhancing the act of sex need systematic evaluation. The empirical evidence for the use of music as an adjunct strategy in the treatment of sexual dysfunctions, though positive and encouraging, is still sparse.

Self-Deception about Fecundity in Women : Modeling the Burley Hypothesis

Concealed fecundity and extended female sexual receptivity have evolved in some primates, including humans, conferring advantages both within primarily monogamous relationships (e.g., benefits from paternity assurance) and from extrapair liaisons (e.g., better access to good genes). As humans evolved the intellectual capacity for decision-making, women became capable of altering their own fertility. In some circumstances, they may choose to ameliorate risks and responsibilities associated with pregnancy by reducing sexual motivation near the perceived most fecund time of their menstrual cycle. But three findings-a general inability of women to accurately recognize their own intervals of fecundity, high variability in ovulation timing, and unconscious transmission and reception of cues associated with fecundity-constitute a physiological and behavioral syndrome that can be considered self-deception. In this study, I develop a descriptive model to determine implications of the hypothesis that these features of female and male physiology and behavior have been shaped by natural selection in response to female decision-making. My analysis shows that consensus motivation for coitus between partners influences both the importance of variable ovulation date and the probability of conception, under the influence of self-deception. It also identifies priorities for future empirical work.

No compelling evidence that more physically attractive young adult women have higher estradiol or progesterone

Putative associations between sex hormones and attractive physical characteristics in women are central to many theories of human physical attractiveness and mate choice. Although such theories have become very influential, evidence that physically attractive and unattractive women have different hormonal profiles is equivocal. Consequently, we investigated hypothesized relationships between salivary estradiol and progesterone and two aspects of women's physical attractiveness that are commonly assumed to be correlated with levels of these hormones: facial attractiveness (N = 249) and waist-to-hip ratio (N = 247). Our analyses revealed no compelling evidence that women with more attractive faces or lower (i.e., more attractive) waist-to-hip ratios had higher levels of estradiol or progesterone. One analysis did suggest that women with more attractive waist-to-hip ratios had significantly higher progesterone, but the relationship was weak and the relationship not significant in other analyses. These results do not support the influential hypothesis that between-women differences in physical attractiveness are related to estradiol and/or progesterone.

Ovulation, Sex Hormones, and Women's Mating Psychology

The dual mating strategy hypothesis proposes that women's preferences for uncommitted sexual relationships with men displaying putative fitness cues increase during the high-fertility phase of the menstrual cycle. Results consistent with this hypothesis are widely cited as evidence that sexual selection has shaped human mating psychology. However, the methods used in most of these studies have recently been extensively criticized. Here we discuss (i) new empirical studies that address these methodological problems and largely report null results and (ii) an alternative model of hormonal regulation of women's mating psychology that can better accommodate these new data.

The role of mating context and fecundability in women's preferences for men's facial masculinity and beardedness

The ovulatory shift hypothesis proposes that women's preferences for masculine physical and behavioral traits are greater at the peri-ovulatory period than at other points of the menstrual cycle. However, many previous studies used self-reported menstrual cycle data to estimate fecundability rather than confirming the peri-ovulatory phase hormonally. Here we report two studies and three analyses revisiting the ovulatory shift hypothesis with respect to both facial masculinity and beardedness. In Study 1, a large sample of female participants (N = 2,161) self-reported their cycle phase and provided ratings for faces varying in beardedness (clean-shaven, light stubble, heavy stubble, full beards) and masculinity (-50%, -25%, natural, +25% and +50%) in a between-subjects design. In Study 2, 68 women provided the same ratings data, in a within-subjects design in which fertility was confirmed via luteinising hormone (LH) tests and analysed categorically. In Study 2, we also measured salivary estradiol (E) and progesterone (P) at the low and high fertility phases of the menstrual cycle among 36 of these women and tested whether shifts in E, P or E:P ratios predicted face preferences. Preferences for facial masculinity and beardedness did not vary as predicted with fecundability in Study 1, or with respect to fertility as confirmed via LH in Study 2. However, consistent with the ovulatory shift hypothesis, increasing E (associated with cyclical increases in fecundability) predicted increases in preferences for relatively more masculine faces; while high P (associated with cyclical decreases in fecundability) predicted increases in preferences for relatively more feminine faces. We also found an interaction between E and preferences for facial masculinity and beardedness, such that stubble was more attractive on un-manipulated than more masculine faces among women with high E. We consider discrepancies between our findings and those of other recent studies and suggest that closer scrutiny of the stimuli used to measure masculinity preferences across studies may help account for the many conflicting findings that have recently appeared regarding cycle phase preference shifts for facial masculinity.

No Compelling Evidence that Preferences for Facial Masculinity Track Changes in Women's Hormonal Status

Although widely cited as strong evidence that sexual selection has shaped human facial-attractiveness judgments, findings suggesting that women’s preferences for masculine characteristics in men’s faces are related to women’s hormonal status are equivocal and controversial. Consequently, we conducted the largest-ever longitudinal study of the hormonal correlates of women’s preferences for facial masculinity (N = 584). Analyses showed no compelling evidence that preferences for facial masculinity were related to changes in women’s salivary steroid hormone levels. Furthermore, both within-subjects and between-subjects comparisons showed no evidence that oral contraceptive use decreased masculinity preferences. However, women generally preferred masculinized over feminized versions of men’s faces, particularly when assessing men’s attractiveness for short-term, rather than long-term, relationships. Our results do not support the hypothesized link between women’s preferences for facial masculinity and their hormonal status.

"I Swear I Will Never Betray You": Factors Reported by Spouses as Helping Them Resist Extramarital Sex in Relation to Gender, Marriage Length, and Religiosity

Studies suggest that married people frequently engage in intimate relationships with people other than their spouses, and the literature has extensively examined motives for doing so. However, less is known about what factors prevent spouses from engaging in extramarital sex. While investment theory, interdependence theory, and moral theories offer insights into this question, they have not been subject to much empirical research. We examine these theories in relation to several characteristics of individuals and couples: gender, length of the marriage, and religiosity. In two studies, 423 participants completed a questionnaire on the perceived importance of 29 reasons to resist the temptation for extramarital sex. Participants also reported the likelihood that they would engage in extramarital sex if the opportunity presented itself. Results show that being female, more religious, and married for less time were associated with greater expectations of refraining from extramarital sex when presented with a hypothetical scenario. Multiple hierarchical regression showed that among factors relevant to conscious decision making, moral standards and fundamental anxieties (fear of remaining alone) predict expectations of refraining from extramarital sex better than concerns about effects on the children or the other participant.

Women's preferences for men's beards show no relation to their ovarian cycle phase and sex hormone levels

According to the ovulatory shift hypothesis, women's mate preferences for male morphology indicative of competitive ability, social dominance, and/or underlying health are strongest at the peri-ovulatory phase of the menstrual cycle. However, recent meta-analyses are divided on the robustness of such effects and the validity of the often-used indirect estimates of fertility and ovulation has been called into question in methodological studies. In the current study, we test whether women's preferences for men's beardedness, a cue of male sexual maturity, androgenic development and social dominance, are stronger at the peri-ovulatory phase of the menstrual cycle compared to during the early follicular or the luteal phase. We also tested whether levels of estradiol, progesterone, and the estradiol to progesterone ratio at each phase were associated with facial hair preferences. Fifty-two heterosexual women completed a two-alternative forced choice preference test for clean-shaven and bearded male faces during the follicular, peri-ovulatory (validated by the surge in luteinizing hormone or the drop in estradiol levels) and luteal phases. Participants also provided for one entire menstrual cycle daily saliva samples for subsequent assaying of estradiol and progesterone. Results showed an overall preference for bearded over clean-shaven faces at each phase of the menstrual cycle. However, preferences for facial hair were not significantly different over the phases of menstrual cycle and were not significantly associated with levels of reproductive hormones. We conclude that women's preferences for men's beardedness may not be related to changes in their likelihood of conception.

Endocrinology of human female sexuality, mating, and reproductive behavior

Hormones orchestrate and coordinate human female sexual development, sexuality, and reproduction in relation to three types of phenotypic changes: life history transitions such as puberty and childbirth, responses to contextual factors such as caloric intake and stress, and cyclical patterns such as the ovulatory cycle. Here, we review the endocrinology underlying women's reproductive phenotypes, including sexual orientation and gender identity, mate preferences, competition for mates, sex drive, and maternal behavior. We highlight distinctive aspects of women's sexuality such as the possession of sexual ornaments, relatively cryptic fertile windows, extended sexual behavior across the ovulatory cycle, and a period of midlife reproductive senescence-and we focus on how hormonal mechanisms were shaped by selection to produce adaptive outcomes. We conclude with suggestions for future research to elucidate how hormonal mechanisms subserve women's reproductive phenotypes.

Standardized protocols for characterizing women's fertility: A data-driven approach

Experts are divided on whether women's cognition and behavior differs between fertile and non-fertile phases of the menstrual cycle. One of the biggest criticisms of this literature concerns the use of indirect, imprecise, and flexible methodologies between studies to characterize women's fertility. To resolve this problem, we provide a data-driven method of best practices for characterizing women's fertile phase. We compared the accuracy of self-reported methods and counting procedures (i.e., the forward- and backward-counting methods) in estimating ovulation using data from 140 women whose fertility was verified with luteinizing hormone tests. Results revealed that no counting method was associated with ovulation with >30% accuracy. A minimum of 39.5% of the days in the six-day fertile window predicted by the counting methods were non-fertile, and correlations between counting method conception probabilities and actual conception probability were weak to moderate, rs=0.11-0.30. Poor results persisted when using a lenient window for predicting ovulation, across alternative estimators of the onset of the next cycle, and when removing outliers to increase the homogeneity of the sample. By contrast, combining counting methods with a relatively inexpensive test of luteinizing hormone predicted fertility with accuracy >95%, but only when specific guidelines were followed. To this end, herein we provide a cost-effective, pragmatic, and standardized protocol that will allow researchers to test whether fertility effects exist or not.

Are Women’s Mate Preferences for Altruism Also Influenced by Physical Attractiveness?

Altruism plays a role in mate choice, particularly in women’s preferences and in long-term (LT) relationships. The current study analyzed how these preferences interacted with another important mate choice variable, physical attractiveness. Here, female participants were presented with photographs of men of varying levels of physical attractiveness, alongside descriptions of them behaving either altruistically or not in different scenarios. The results showed women preferred altruistic men, particularly in LT relationships and that this interacted with physical attractiveness such that being both attractive and altruistic made a man more desirable than just the sum of the two desirable parts. Also, being altruistic made low attractive men more desirable but only for LT relationships. Finally, men who were just altruistic were rated more desirable than men who were just attractive, especially for LT relationships. Overall, these findings are discussed in terms of the role of altruism in mate choice, particularly in LT relationships and directions of future research.