Changes in women's sexual interests and their partners' mate-retention tactics across the menstrual cycle: evidence for shifting conflicts of interest

Because ancestral women could have obtained genetic benefits through extra-pair sex only near ovulation, but paid costs of extra-pair sex throughout the cycle, one might expect selection to have shaped female interest in partners, other than primary partners, to be greater near ovulation than during the luteal phase. Because men would have paid heavier costs if their partners had extra-pair sex near ovulation, one might also expect selection to have shaped males' efforts to track their primary partners' whereabouts to be increased near ovulation, relative to the luteal phase. Women filled out questionnaires about their sexual interests and their partners' mate-retention tactics twice: once within 5 days before a lutenizing hormone surge and once during the luteal phase. Results showed that: (i) women reported greater sexual interest in, and fantasy about, non-primary partners near ovulation than during the luteal phase; (ii) women did not report significantly greater sexual interest in, and fantasy about, primary partners near ovulation; (iii) women reported that their primary partners were both more attentive and more proprietary near ovulation.     

Intersexual conflict across women's ovulatory cycle

A growing literature shows that the features women find particularly attractive in men vary across the ovulatory cycle. Women furthermore appear to more frequently report attraction to men other than primary partners when they are fertile in their cycle than in the infertile luteal phase. Previous studies have shown that men are more vigilant of or attentive to their primary partners during the fertile phase compared to the luteal phase. This study had several aims: First, to replicate and extend previous findings concerning men's vigilance of partners using male as well as female reports of men's behavior; second, to examine changes in women's behavior toward partners across the cycle; third, to examine ways in which women resist men's attempts to mate-guard across the cycle. Results indicate that (a) men are particularly self-assertive toward partners when their partners are fertile; (b) similarly, women are especially self-assertive toward partners when they are fertile; (c) women report engaging in more behaviors that resist male vigilance and mate guarding when they are fertile, especially in ways that are unobservable to male partners; and (d) these effects are especially strong when women themselves report greater attraction to men other than partners when they are fertile, compared to the luteal phase.     

Ovulatory Shifts in Women��s Attractions to Primary Partners and Other Men: Further Evidence of the Importance of Primary Partner Sexual Attractiveness

Previous research has documented shifts in women’s attractions to their romantic partner and to men other than their partner across the ovulation cycle, contingent on the degree to which her partner displays hypothesized indicators of high-fitness genes. The current study set out to replicate and extend this finding. Forty-one couples in which the woman was naturally cycling participated. Female partners reported their feelings of in-pair attraction and extra-pair attraction on two occasions, once on a low-fertility day of the cycle and once on a high-fertility day of the cycle just prior to ovulation. Ovulation was confirmed using luteinizing hormone tests. We collected two measures of male partner sexual attractiveness. First, the women in the study rated their partner’s sexual attractiveness. Second, we photographed the partners and had the photos independently rated for attractiveness. Shifts in women’s in-pair attractions across the cycle were significantly moderated by women’s ratings of partner sexual attractiveness, such that the less sexually attractive women rated their partner, the less in-pair attraction they reported at high fertility compared with low fertility (partial r = .37, p _dir = .01). Shifts in women’s extra-pair attractions across the cycle were significantly moderated by third-party ratings of partner attractiveness, such that the less attractive the partner was, the more extra-pair attraction women reported at high relative to low fertility (partial r = −.33, p _dir = .03). In line with previous findings, we found support for the hypothesis that the degree to which a woman’s romantic partner displays indicators of high-fitness genes affects women’s attractions to their own partner and other men at high fertility.     

Changes in Sleep Time and Sleep Quality across the Ovulatory Cycle as a Function of Fertility and Partner Attractiveness

Research suggests that near ovulation women tend to consume fewer calories and engage in more physical activity; they are judged to be more attractive, express greater preferences for masculine and symmetrical men, and experience increases in sexual desire for men other than their primary partners. Some of these cycle phase shifts are moderated by partner attractiveness and interpreted as strategic responses to women''s current reproductive context. The present study investigated changes in sleep across the ovulatory cycle, based on the hypothesis that changes in sleep may reflect ancestral strategic shifts of time and energy toward reproductive activities. Participants completed a 32-day daily diary in which they recorded their sleep time and quality for each day, yielding over 1,000 observations of sleep time and quality. Results indicated that, when the probability of conception was high, women partnered with less attractive men slept more, while women with more attractive partners slept less.     

Male sexual attractiveness predicts differential ovulatory shifts in female extra-pair attraction and male mate retention

Because ancestral women faced trade-offs in choosing mates, they may have evolved to pursue a dual-mating strategy in which they secured investment through one partner and obtained good genes through others. The dual-mating theory predicts that women will display greater interest in extra-pair sex near ovulation, especially if they are mated to a primary male partner who is low in sexual attractiveness. Forty-three normally ovulating women rated their partner's sexual attractiveness and separately reported their own desires and their partner's mate retention behaviors at high and low fertility (confirmed using luteinizing hormone tests). In the high-fertility session relative to the low, women who assessed their partners as being lower in sexual attractiveness reported greater extra-pair desires and more expressed love and attention from their male partners. Women's desire for their own partners did not differ significantly between high and low-fertility sessions.     

Effects of partner conception risk phase on male perception of dominance in faces

Several studies have suggested that women may prefer to engage in extra-pair copulations with males who appear dominant and to do so near ovulation. While there is some evidence that males are more jealous of dominant rivals and more proprietary when their partners are near ovulation, there is none that suggests the existence of counterstrategic perceptual shifts that mirror those seen in women. We provide such evidence here. Composites of male faces that were either high or low in rated dominance were presented to male participants who provided ratings of dominance. A three-way interaction between stimulus-face dominance, partner conception risk phase, and partner oral contraceptive use was found; men whose partners did not use an oral contraceptive and were in the high conception risk phase of their cycle displayed increased dominance ratings of high-dominance male faces. We conclude that males have evolved counterstrategies to deal with female infidelity that include an overattribution of dominance to those rivals most likely to present a threat at times when that threat is greatest. This overattribution is likely to lead to increases in jealousy and mate-retention behaviors.     

Women's estradiol predicts preference for facial cues of men's testosterone

A growing body of research has shown that women express stronger attraction to more masculine traits when they are tested near ovulation than when tested during other times in the menstrual cycle. Although these effects have been interpreted as increased preferences for markers of elevated testosterone during times in the cycle when conception is most likely, no previous studies have directly demonstrated that women express stronger attraction to higher testosterone men at different times in the cycle. In addition, little research has addressed which hormonal or other physiological mechanisms may regulate temporal shifts in women's attractiveness judgments. In this research, we demonstrate that women with higher estradiol concentrations exhibit stronger preferences for the faces of men with higher testosterone concentrations, and that women's testosterone preference and estradiol curves track one another across days of the cycle. The findings are the first direct demonstration in humans that hormone concentrations in one sex are associated with attraction to cues of hormonal status in the opposite sex. The results support a functional role for estradiol in calibrating women's mating psychology to indices of their current fertility, analogous to similar processes that have been documented in nonhuman species. A strong correlation between estradiol and testosterone preference specifically during the luteal phase further suggests that women's mate preferences may track their fertility between different cycles in addition to being calibrated to the timing of ovulation within individual cycles.     

Preferences for masculinity in male bodies change across the menstrual cycle

In human females cyclic shifts in preference have been documented for odour and physical and behavioral male traits. Women prefer the smell of dominant males, more masculine male faces and men behaving more dominantly when at peak fertility than at other times in their menstrual cycle. Here we examine variation in preferences for body sexual dimorphism. Across two studies, both between- and within-participant, we show that women prefer greater masculinity in male bodies at times when their fertility is likely highest, in the follicular phase of their cycle. Shifts were seen when rating for a short-term but not when rating for a long-term relationship. In line with studies showing similar effects for facial sexual dimorphism, we also show that women prefer greater masculinity when they think themselves attractive than when they think themselves less attractive. These results indicate that women's preferences for sexual dimorphism in male bodies follow a similar pattern as found for sexual dimorphism and dominance in other domains and such differences in preference may serve a similar function. Cyclic preferences could influence women to select partners when most likely to become pregnant that possess traits that may be most likely to maximize their offspring's quality via attraction to masculinity or serve to help acquire investment via attraction to femininity.     

Body odor attractiveness as a cue of impending ovulation in women: evidence from a study using hormone-confirmed ovulation

Scent communication plays a central role in the mating behavior of many nonhuman mammals but has often been overlooked in the study of human mating. However, a growing body of evidence suggests that men may perceive women's high-fertility body scents (collected near ovulation) as more attractive than their low-fertility body scents. The present study provides a methodologically rigorous replication of this finding, while also examining several novel questions. Women collected samples of their natural body scent twice--once on a low-fertility day and once on a high-fertility day of the ovulatory cycle. Tests of luteinizing hormone confirmed that women experienced ovulation within two days of their high-fertility session. Men smelled each woman's high- and low-fertility scent samples and completed discrimination and preference tasks. At above-chance levels, men accurately discriminated between women's high- and low-fertility scent samples (61%) and chose women's high-fertility scent samples as more attractive than their low-fertility scent samples (56%). Men also rated each scent sample on sexiness, pleasantness, and intensity, and estimated the physical attractiveness of the woman who had provided the sample. Multilevel modeling revealed that, when high- and low-fertility scent samples were easier to discriminate from each other, high-fertility scent samples received even more favorable ratings compared with low-fertility scent samples. This study builds on a growing body of evidence indicating that men are attracted to cues of impending ovulation in women and raises the intriguing question of whether women's cycling hormones influence men's attraction and sexual approach behavior.     

Men's facial masculinity predicts changes in their female partners' sexual interests across the ovulatory cycle,whereas men's intelligence does not

A substantial body of work demonstrates that women's mate preferences change across the ovulatory cycle. When fertile in their cycles, women are especially attracted to masculine features (e.g., faces, voices, bodies), socially dominant behavior, and male scents associated with body symmetry and social dominance. Women may also find intelligent men particularly attractive when fertile, though findings are mixed. Related research shows that, on average, romantically-involved women report stronger sexual attraction to men other than their pair-bond partners, but not partners, when fertile, and especially when their partners lack features fertile women prefer (e.g., symmetry). In the current study, we examined whether women's patterns of sexual interests across the cycle are similarly moderated by partners' facial masculinity, facial attractiveness, and intelligence. Results revealed predicted effects of male partners’ facial masculinity but none for partners’ intelligence. Facial attractiveness may have effects, but we find no evidence that it does so independently of facial masculinity.     

Ovulatory shifts in human female ornamentation: near ovulation, women dress to impress

Humans differ from many other primates in the apparent absence of obvious advertisements of fertility within the ovulatory cycle. However, recent studies demonstrate increases in women's sexual motivation near ovulation, raising the question of whether human ovulation could be marked by observable changes in overt behavior. Using a sample of 30 partnered women photographed at high and low fertility cycle phases, we show that readily-observable behaviors - self-grooming and ornamentation through attractive choice of dress - increase during the fertile phase of the ovulatory cycle. At above-chance levels, 42 judges selected photographs of women in their fertile (59.5%) rather than luteal phase (40.5%) as "trying to look more attractive." Moreover, the closer women were to ovulation when photographed in the fertile window, the more frequently their fertile photograph was chosen. Although an emerging literature indicates a variety of changes in women across the cycle, the ornamentation effect is striking in both its magnitude and its status as an overt behavioral difference that can be easily observed by others. It may help explain the previously documented finding that men's mate retention efforts increase as their partners approach ovulation.     

Menstrual cycle, trait estrogen level, and masculinity preferences in the human voice

Men with low testosterone (feminine men) invest in relationships and offspring more than men with high testosterone (masculine men). Women's attraction to testosterone dependent traits (e.g. masculine face shape) is enhanced during the late-follicular, fertile phase of the menstrual cycle. Attractive, feminine women have stronger preferences for masculine men as possible long-term partners than less attractive, masculine women. We manipulated 2 testosterone related vocal traits (voice pitch and apparent vocal-tract length) in voices to test if women prefer masculinized men's voices to feminized men's voices; masculinity preferences are enhanced at the fertile (late-follicular) menstrual cycle phase; the amount that masculinity preferences shift cyclically relates to average estrone-3-glucuronide concentration (the primary urinary metabolite of estrone, E3G). We found women displayed general masculinity preferences for men's voices; masculinity preferences were greater in the fertile (late-follicular) phase of the cycle than the non-fertile (early-follicular and luteal) phase; and this effect was most pronounced for women with low average E3G concentration. As feminine women (i.e. those with high average E3G levels) are most able to obtain investment even from masculine men, these women may not need to change their mating preference or strategy during the menstrual cycle as much as masculine women.     

Same-Sex Gaze Attraction Influences Mate-Choice Copying in Humans

Mate-choice copying occurs when animals rely on the mating choices of others to inform their own mating decisions. The proximate mechanisms underlying mate-choice copying remain unknown. To address this question, we tracked the gaze of men and women as they viewed a series of photographs in which a potential mate was pictured beside an opposite-sex partner; the participants then indicated their willingness to engage in a long-term relationship with each potential mate. We found that both men and women expressed more interest in engaging in a relationship with a potential mate if that mate was paired with an attractive partner. Men and women''s attention to partners varied with partner attractiveness and this gaze attraction influenced their subsequent mate choices. These results highlight the prevalence of non-independent mate choice in humans and implicate social attention and reward circuitry in these decisions.     

Within-cycle fluctuations in progesterone negatively predict changes in both in-pair and extra-pair desire among partnered women

Grebe et al. (2016) argued that women's sexual interest in their own partners may be under different hormonal regulation than their sexual desire for other men. They measured partnered women's salivary hormones and reports of attraction to different categories of men at two time points separated by one week. Change in progesterone positively predicted change in women's desire for their own partners, whereas change in estradiol was a negative predictor. These results are opposite to those we previously reported for the hormonal prediction of general sexual desire in a study that employed frequent hormone sampling across multiple menstrual cycles (Roney and Simmons, 2013). Here, to test replication of the Grebe et al. findings, we assessed hormonal predictors of targeted in-pair and extra-pair desire among the subset of the sample from our 2013 paper who reported being in romantic relationships. Contrary to Grebe et al. (2016), we found that within-cycle fluctuations in progesterone were negatively correlated with changes in women's desire for both their own partners and other men. In addition, both in-pair and extra-pair desire were elevated within the fertile window and lowest during the luteal phase. Our findings contradict the idea that partner-specific desire has a unique form of hormonal regulation, and instead support a general elevation of sexual motivation associated with hormonal indices of fecundity. Discussion focuses on possible reasons for the discrepancies in findings between our study and that of Grebe et al. (2016), and on the evolved functions of women's sexual motivation.     

I Want What She’s Having

A variety of non-human females do not select male partners independently. Instead they favor males having previous associations with other females, a phenomenon known as mate copying. This paper investigates whether humans also exhibit mate copying and whether consistent positive information about a man’s mate value, and a woman’s age and self-perceived mate value (SPMV), influence her tendency to copy the mate choices of others. Female university students (N?=?123) rated the desirability of photographed men pictured alone or with one, two, or five women represented by silhouettes. In accordance with the visual arrays, men were described as currently in a romantic relationship; having previously been in one, two, or five relationships; or not having had a romantic relationship in the past 4 years. Women generally rated men pictured with one or two previous partners as more desirable than those with none. Men depicted with five previous partners, however, were found to be less desirable. Younger, presumably less experienced women had a greater tendency to mate copy compared with older women, but high SPMV did not predict greater levels of mate copying. The findings reaffirmed and expanded those suggesting that women do not make mate choices independently.     

Conditional expression of women's desires and men's mate guarding across the ovulatory cycle

Thirty-eight normally cycling women provided daily reports of sexual interests and feelings for 35 days. Near ovulation, both pair-bonded and single women reported feeling more physically attractive and having greater interest in attending social gatherings where they might meet men. Pair-bonded women who were near ovulation reported greater extra-pair flirtation and greater mate guarding by their primary partner. As predicted, however, these effects were exhibited primarily by women who perceived their partners to be low on hypothesized good genes indicators (low in sexual attractiveness relative to investment attractiveness). Ovulation-contingent increases in partner mate guarding were also moderated by female physical attractiveness; midcycle increases in mate guarding were experienced primarily by less attractive women, whereas more attractive women experienced relatively high levels of mate guarding throughout their cycle. These findings demonstrate ovulation-contingent shifts in desires and behaviors that are sensitive to varying fitness payoffs, and they provide support for the good genes hypothesis of human female extra-pair mating. The daily assessment method provides an important supplement to existing studies using scheduled laboratory visits as the purpose of the study (examining cycle-related variation) is not known by participants.     

Populational differences in attractiveness judgements of male and female faces: Comparing British and Jamaican samples

In the UK and Japan, both men and women prefer somewhat feminised opposite-sex faces, especially when choosing a long-term partner. Such faces are perceived as more honest, caring, and sensitive; traits that may be associated with successful male parental investment. By contrast, women prefer less feminised faces for short-term relationships and when they are near ovulation. As genetic quality may be associated with facial masculinity, women may ‘trade-off’ cues between genetic quality and paternal investment in potential partners. No analogous trade-off has been suggested to influence men's preferences, as both attributions of prosociality and potential cues to biological quality are associated with facial femininity in female faces. Ecological and cultural factors may influence the balance of trade-offs leading to populational differences in preferences. We predicted that Jamaican women would prefer more masculine faces than British women do because parasite load is higher in Jamaica, medical care less common (historically and currently), and male parental investment less pronounced. Male preferences, however, were predicted to vary less cross-culturally, as no trade-off has been identified in female facial characteristics. We constructed masculinised and feminised digital male and female face stimuli of three populations (Jamaican, Japanese, and British) and presented them to men and women in Jamaica and in Britain. The results demonstrated that Jamaican women preferred more masculine male faces than their British counterparts did. Jamaican men tended to prefer more masculine female faces than did British men did, but this effect was complicated by an interaction suggesting that more feminised faces were preferred within culture.     

Prevalence of and risk factors associated with alcohol abuse in Moshi, northern Tanzania

This study aimed to assess the prevalence of and risk factors associated with alcohol abuse among women and men in Moshi in northern Tanzania. Alcohol abuse was measured by a CAGE score of 2-4, versus 0-1 for no alcohol abuse (Ewing, 1984). Crude and adjusted logistic regression models determined odds ratios (OR) and 95% confidence intervals (95% CI) of alcohol abuse by characteristics of, respectively, women with partners (n=1200), women without partners (n=614) and men (n=788) (women's partners). Prevalence of alcohol abuse was 7.0% (95% CI: 5.6-8.4) among women with partners, 9.3% (95% CI: 7.0-11.6) among women without partners, and more than double among men at 22.8% (95% CI: 19.9-25.8). In general, Christians had higher alcohol abuse than Muslims or other religions, as did Chagga men compared with men of other ethnic groups. Other socio-demographic characteristics, such as education or income, were not significant. Sexual behaviours were significant predictors of alcohol abuse. For example, women without partners who reported more than two partners in the last year had higher alcohol abuse compared with women reporting no partners (OR=8.75; 95% CI: 2.37-32.31), as did men reporting it is 'OK to hit a partner' for any reason (OR=1.79; 95% CI: 1.16-2.77) compared with men who did not. HIV-1 infection was not significantly associated with alcohol abuse by women or men. The Christian Church in Moshi should consider raising awareness about the harmful effects of high alcohol use among its adherents. Comprehensive programmes focusing on reducing number of partners and alcohol use, particularly by men, are needed in this community.     

Steroid Hormones and Facial Traits in The Recognition of A Potential Rival in Men

There is evidence that the cognitive skills that enable an individual to evaluate their own physical characteristics and those of others are an important strategy for recognizing a potential rival in intrasexual competition in humans. It has been shown that these strategies are facilitated by steroid hormones such as testosterone (T) and cortisol (C). This study examines whether men recognize as attractive some facial characteristics of other men that the literature reports as attractive to women when observing the faces of other men, under the hypothesis that the presence of these features indicates a potential rival. The characteristics evaluated were facial fluctuating asymmetry (FA), dominance (D), and assertiveness (A). In addition, we investigated whether the recognition of these facial characteristics depended upon the characteristics of the evaluator, that is, of the man's own FA, D, and A, or on the concentration of T and C in saliva. We found that evaluators with greater FA (asymmetric faces) and lower concentrations of C rated the faces of more symmetrical men as more attractive to women and as the most likely to represent potential rivals. Men with asymmetric faces exhibited higher levels of T than low FA males, although the difference was not significant. Conversely, men with low levels of FA (symmetric) identified the faces of more assertive men as the most attractive to women and the most likely to represent potential rivals. We concluded that men with high FA levels are more prone to recognize a potential rival in others according to female preferences, and this identification enables them to reduce the cost of competition.