Women in their mid-follicular phase outcompete hormonal contraceptive users, an effect partially explained by relatively greater progesterone and cortisol reactivity to competition.

Early evidence suggests that hormonal contraceptive (HC) use alters psychological functioning and competitive behavior. Yet, there is limited data on endocrine models for explaining how HC use affects these outcomes. In this pre-registered and open-data study, we test if HC users and naturally cycling (NC) females in their low (mid-follicular) and high (mid-luteal) progesterone phase differ in competitive persistence and whether progesterone and cortisol reactivity mediate of this effect. HC users (N = 73) in the active hormone-exposure phase and NC participants in the mid-follicular (N = 69) or mid-luteal (N = 72) phase completed two behavioral measures of competitive persistence, holding up a weight for time followed by attempting to solve an unsolvable anagram. Participants also completed measures of handgrip strength and self-reported competitiveness as well as gave saliva samples before and after the tasks for hormone assay. Results showed that NC-follicular group had greater competitive persistence in the weight-holding task compared to both NC-luteal (d = 0.38) and HC use (d = 0.43) groups independent of physical strength and self-reported competitiveness covariates. Although anagram task performance showed similar trends for group differences, analyses for this task were inconclusive. Baseline progesterone did not mediate the effect of cycle phase group on competitive persistence. HC users showed relatively blunted cortisol and progesterone reactivity, and this effect partially mediated the difference in competitive persistence between HC users and the NC-follicular group. In sum, results suggest that HC use could downregulate competitive behavior at least partly by dampening cortisol-progesterone reactivity. These findings offer a new endocrine model for understanding HC use and cycle phase effects on motivational and energetic outcomes required for optimal performance in competitive contexts.

Societies should not ignore their incel problem.

Involuntarily celibate men ('incels') commonly advocate for societal disruption, including violence toward women. Their anger can make them susceptible to radicalization, revolution, or reactionary hostility. Research efforts aimed at identifying the causes and consequences of incels' beliefs are needed to address this growing problem.

When fertile, women seek status via prestige but not dominance.

Biological predictors of human dominance are hotly contested, with far-reaching implications for psychological sex differences and the placement of men and women in the social hierarchy. Most investigations have focused on dominance in men and testosterone, with diminished attention paid to dominance in women and other biological mechanisms. Investigating biological influences on other routes to status attainment popular among women-such as via prestige in addition to dominance-have also been neglected. Here, I examined whether status seeking via prestige and via dominance covaried with fertility probability in a citizen science project spanning 14 countries and 4 world regions. Across 4,179 observations, participants tracked their menstrual cycle characteristics, motivation for prestige and dominance, dominance contest outcomes, and three domains of self-esteem. Self-esteem is predicted by status within a group and helps individuals navigate social hierarchies. Bayesian mixed models controlling for menstruation indicated that the motivation to obtain status via prestige but not dominance peaked when conception was most likely, as did dominance contest losses and two self-esteem domains. Fertility appears to reorient female psychology toward prestige-based strategies to success, enhancing women's desire for social capital through influence and admiration but not through fear, coercion, or intimidation. These insights fundamentally advance the understanding of the biological correlates of status seeking among women. They further suggest that fertility motivates not only mating competition but gaining rank and positive regard in social hierarchies.

Experimental and cross-cultural evidence that parenthood and parental care motives increase social conservatism.

Differences in attitudes on social issues such as abortion, immigration and sex are hugely divisive, and understanding their origins is among the most important tasks facing human behavioural sciences. Despite the clear psychological importance of parenthood and the motivation to provide care for children, researchers have only recently begun investigating their influence on social and political attitudes. Because socially conservative values ostensibly prioritize safety, stability and family values, we hypothesized that being more invested in parental care might make socially conservative policies more appealing. Studies 1 (preregistered; n = 376) and 2 (n = 1924) find novel evidence of conditional experimental effects of a parenthood prime, such that people who engaged strongly with a childcare manipulation showed an increase in social conservatism. Studies 3 (n = 2610, novel data from 10 countries) and 4 (n = 426 444, World Values Survey data) find evidence that both parenthood and parental care motivation are associated with increased social conservatism around the globe. Further, most of the positive association globally between age and social conservatism is accounted for by parenthood. These findings support the hypothesis that parenthood and parental care motivation increase social conservatism.

Hormonal contraceptives as disruptors of competitive behavior: Theoretical framing and review.

Emerging evidence suggests that hormonal contraceptives (HCs) impact psychological outcomes through alterations in neurophysiology. In this review, we first introduce a theoretical framework for HCs as disruptors of steroid hormone modulation of socially competitive attitudes and behaviors. Then, we comprehensively examine prior research comparing HC users and non-users in outcomes related to competition for reproductive, social, and financial resources. Synthesis of 46 studies (n = 16,290) led to several key conclusions: HC users do not show the same menstrual cycle-related fluctuations in self-perceived attractiveness and some intrasexual competition seen in naturally-cycling women and, further, may show relatively reduced status- or achievement-oriented competitive motivation. However, there a lack of consistent or compelling evidence that HC users and non-users differ in competitive behavior or attitudes for mates or financial resources. These conclusions are tentative given the notable methodological limitations of the studies reviewed. Implications and recommendations for future research are discussed.

Sex-dependent selection, ageing, and implications for "staying alive".

Incorporating theoretic insights from ageing biology could advance the "staying alive" hypothesis. Higher male extrinsic mortality can weaken selection against ageing-related diseases and self-preservation, leading to high male intrinsic mortality. This may incidentally result in female-biased longevity-promoting traits, a possibility that will require rigorous testing in order to disentangle from the adaptive self-preservation hypothesis presented in the target article.

Widespread Promiscuity and Cheap Weddings: Can "Low-Value" Sexual Relationships Make Certain Individuals More Sexually Conservative?

Attitudes toward sexual relationships can have evolutionary underpinnings because these attitudes often serve, or at least reflect, the attitude holder's mating self-interest. Sexually restricted individuals, for example, hold conservative attitudes toward same-sex and opposite-sex sexual relationships because conservative attitudes benefit their mating strategies (e.g., monogamy). Certain mating market cues, however, can shift attitudes. In two experiments recruiting Americans and Australians (total N = 1298), we took a data-driven approach to test whether experimental manipulations of (1) promiscuity among either homosexuals (gays and lesbians) or heterosexuals and (2) the financial amount that either homosexuals (gays and lesbians) or heterosexuals invest in weddings would shift attitudes toward same-sex marriage, dating, and romantic spending. In Experiment 1, we did not replicate previous findings that homosexual promiscuity affects attitudes to same-sex marriage, nor did we find any effects of priming heterosexual promiscuity. However, priming participants with the notion that either homosexuals or heterosexuals were highly promiscuous increased support for traditional relationship norms among sexually restricted Australian (but not American) men. This effect was smaller when we controlled for participant sexual orientation, because primes of high homosexual or heterosexual promiscuity increased support for these traditional norms in exclusively heterosexual Australians, but decreased support in non-heterosexual Australians. Experiment 2 found that American and Australian men's opposition to same-sex marriage increased when they were led to believe that either homosexual or heterosexual weddings were cheap, even when controlling for participant sexual orientation. Overall, results provide some support for the argument that mating market cues affect attitudes toward sexual relationships.

Incel Activity on Social Media Linked to Local Mating Ecology.

Young men with few prospects of attracting a mate have historically threatened the internal peace and stability of societies. In some contemporary societies, such involuntary celibate-or incel-men promote much online misogyny and perpetrate real-world violence. We tested the prediction that online incel activity arises via local real-world mating-market forces that affect relationship formation. From a database of 4 billion Twitter posts (2012-2018), we geolocated 321 million tweets to 582 commuting zones in the continental United States, of which 3,649 tweets used words peculiar to incels and 3,745 were about incels. We show that such tweets arise disproportionately within places where mating competition among men is likely to be high because of male-biased sex ratios, few single women, high income inequality, and small gender gaps in income. Our results suggest a role for social media in monitoring and mitigating factors that lead young men toward antisocial behavior in real-world societies.

Misogynistic Tweets Correlate With Violence Against Women.

How online social behavior covaries with real-world outcomes remains poorly understood. We examined the relationship between the frequency of misogynistic attitudes expressed on Twitter and incidents of domestic and family violence that were reported to the Federal Bureau of Investigation. We tracked misogynistic tweets in more than 400 areas across 47 American states from 2013 to 2014. Correlation and regression analyses found that misogynistic tweets were related to domestic- and family-violence incidents in those areas. A cross-lagged model showed that misogynistic tweets positively predicted domestic and family violence 1 year later; however, this effect was small. Results were robust to several known predictors of domestic violence. Our findings identify geolocated online misogyny as co-occurring with domestic and family violence. Because the longitudinal relationship between misogynistic tweets and domestic and family violence was small and conducted at the societal level, more research with multilevel data might be useful in the prediction of future violence.

Male descendant kin promote conservative views on gender issues and conformity to traditional norms.

Political and social attitudes have been shown to differ by sex in a way that tracks individual self-interest. We propose that these attitudes also change strategically to serve the best interests of either male or female kin. To test this hypothesis, we developed a measure of gendered fitness interests (GFI) - an index which reflects the sex, relatedness and residual reproductive value of close kin. We predicted that people with male-biased GFI (i.e. people with more male kin of a reproductive age) would have more conservative attitudes towards gender-related issues (e.g. gender roles, women's rights, abortion rights). An online study using an American sample (N = 560) found support for this hypothesis. Further analyses revealed that this relationship was driven not only by people's own sex and reproductive value but also by those of their descendant kin. Exploratory analyses also found a positive association between male-biased GFI and a measure of conformity, as well as a smaller association between male-biased GFI and having voted Republican in the last election. Both of these associations were statistically mediated by gender-related conservatism. These findings are consistent with the hypothesis that GFI influences sociopolitical attitudes.

In the context of romantic attraction, beautification can increase assertiveness in women.

Can beautification empower women to act assertively? Some women report that beautification is an agentic and assertive act, whereas others find beautification to be oppressive and disempowering. To disentangle these effects, in the context of romantic attraction we conducted the first experimental tests of beautification-on psychological and behavioral assertiveness. Experiment 1 (N = 145) utilized a between-subjects design in which women used their own clothing, make-up, and accessories to adjust their appearance as they normally would for a "hot date" (beautification condition) or a casual day at home with friends (control condition). We measured implicit, explicit, and behavioral assertiveness, as well as positive affect and sexual motivation. Experiment 2 (N = 40) sought to conceptually replicate Experiment 1 using a within-subject design and different measures of assertiveness. Women completed measures of explicit assertiveness and assertive behavioral intentions in three domains, in whatever clothing they were wearing that day then again after extensively beautifying their appearance. In Experiment 1, we found that women demonstrated higher psychological assertiveness after beautifying their appearance, and that high sexual motivation mediated the effect of beautification on assertive behavior. All effects were independent of positive affect. Experiment 2 partially replicated Experiment 1. These experiments provide novel insight into the effects of women's appearance-enhancing behaviors on assertiveness by providing evidence that beautification may positively affect assertiveness in women under some circumstances.

On Attenuated Interactions, Measurement Error, and Statistical Power: Guidelines for Social and Personality Psychologists.

The replication crisis has seen increased focus on best practice techniques to improve the reliability of scientific findings. What remains elusive to many researchers and is frequently misunderstood is that predictions involving interactions dramatically affect the calculation of statistical power. Using recent papers published in Personality and Social Psychology Bulletin (PSPB), we illustrate the pitfalls of improper power estimations in studies where attenuated interactions are predicted. Our investigation shows why even a programmatic series of six studies employing 2 × 2 designs, with samples exceeding N = 500, can be woefully underpowered to detect genuine effects. We also highlight the importance of accounting for error-prone measures when estimating effect sizes and calculating power, explaining why even positive results can mislead when power is low. We then provide five guidelines for researchers to avoid these pitfalls, including cautioning against the heuristic that a series of underpowered studies approximates the credibility of one well-powered study.

The Effects of the Mating Market, Sex, Age, and Income on Sociopolitical Orientation : Insights from Evolutionary Theory and Sexual Economics Theory.

Sociopolitical attitudes are often the root cause of conflicts between individuals, groups, and even nations, but little is known about the origin of individual differences in sociopolitical orientation. We test a combination of economic and evolutionary ideas about the degree to which the mating market, sex, age, and income affect sociopolitical orientation. We collected data online through Amazon's Mechanical Turk from 1108 US participants who were between 18 and 60, fluent in English, and single. While ostensibly testing a new online dating website, participants created an online dating profile and described people they would like to date. We manipulated the participants' popularity in the mating market and the size of the market (i.e., the number of ideal partners in the market) and then measured participants' sociopolitical attitudes. The sociopolitical attitudes were reduced to five dimensions via Principal Components Analysis (Sociosexuality, Benevolent Sexism, Wealth Redistribution, Nonconforming Behaviors, and Traditional Family Values). Both manipulations affected attitudes toward wealth redistribution but were largely not significant predictors of the other dimensions. Men reported more unrestricted sociosexual attitudes, and more support for benevolent sexism and traditional family values, than women did, and women supported wealth redistribution more than men did. There was no sex difference in accepting nonconforming behaviors. Younger people and people with lower incomes were more liberal than older people and people with higher incomes, respectively, regardless of sex. Overall, effects were largely not interactive, suggesting that individual differences in sociopolitical orientation may reflect strategic self-interest and be more straightforward than previously predicted.

Status anxiety mediates the positive relationship between income inequality and sexualization.

Income inequality generates and amplifies incentives, particularly incentives for individuals to elevate or maintain their status, with important consequences for the individuals involved and aggregate outcomes for their societies [R. G. Wilkinson, K. E. Pickett, Annu. Rev. Sociol. 35, 493-511 (2009)]. Economically unequal environments intensify men's competition for status, respect, and, ultimately, mating opportunities, thus elevating aggregate rates of violent crime and homicide [M. Daly, M. Wilson, Evolutionary Psychology and Motivation (2001)]. Recent evidence shows that women are more likely to post "sexy selfies" on social media and that they spend more on beautification in places where inequality is high rather than low [K. R. Blake, B. Bastian, T. F. Denson, et al., Proc. Natl. Acad. Sci. U.S.A. 115, 8722-8727 (2018)]. Here we test experimentally for causal links between income inequality and individual self-sexualization and status-related competition. We show that manipulating income inequality in a role-playing task indirectly increases women's intentions to wear revealing clothing and that it does so by increasing women's anxiety about their place in the social hierarchy. The effects are not better accounted for by wealth/poverty than by inequality or by modeling anxiety about same-sex competitors in place of status anxiety. The results indicate that women's appearance enhancement is partly driven by status-related goals.

What drives female objectification? An investigation of appearance-based interpersonal perceptions and the objectification of women.

Previous research finds that both men and women perceive sexualized women as lacking in certain human qualities such as mental capacity and moral status. The mechanism underlying this effect, however, is unclear. The present two studies test how appearance-based judgements affect the degree to which a broad sample of women are objectified. In Study 1 (N = 279), full-body images of women wearing different clothing outfits were rated by male and female participants on perceived attractiveness, sexual intent and age. In Study 2, male and female participants (N = 1,695) viewed these same images from Study 1 and rated them on two dimensions of objectification (agency and patiency). We analyzed associations between these dimensions of objectification and the averaged appearance-based perceptions from Study 1. We find that women perceived as more open to casual sex are attributed less mental capacity and less moral status. We also find that participants tend to associate attractiveness with greater mental and moral status in women, but we find only limited evidence that perceived age influences objectification. Our findings suggest that although positive attractiveness biases may mitigate the amount a woman is objectified, greater female objectification may be prompted by observers' negative stereotypes of promiscuous women.

Income inequality not gender inequality positively covaries with female sexualization on social media.

Publicly displayed, sexualized depictions of women have proliferated, enabled by new communication technologies, including the internet and mobile devices. These depictions are often claimed to be outcomes of a culture of gender inequality and female oppression, but, paradoxically, recent rises in sexualization are most notable in societies that have made strong progress toward gender parity. Few empirical tests of the relation between gender inequality and sexualization exist, and there are even fewer tests of alternative hypotheses. We examined aggregate patterns in 68,562 sexualized self-portrait photographs ("sexy selfies") shared publicly on Twitter and Instagram and their association with city-, county-, and cross-national indicators of gender inequality. We then investigated the association between sexy-selfie prevalence and income inequality, positing that sexualization-a marker of high female competition-is greater in environments in which incomes are unequal and people are preoccupied with relative social standing. Among 5,567 US cities and 1,622 US counties, areas with relatively more sexy selfies were more economically unequal but not more gender oppressive. A complementary pattern emerged cross-nationally (113 nations): Income inequality positively covaried with sexy-selfie prevalence, particularly within more developed nations. To externally validate our findings, we investigated and confirmed that economically unequal (but not gender-oppressive) areas in the United States also had greater aggregate sales in goods and services related to female physical appearance enhancement (beauty salons and women's clothing). Here, we provide an empirical understanding of what female sexualization reflects in societies and why it proliferates.

Resolving speculations of methodological inadequacies in the standardized protocol for characterizing women's fertility: Comment on Lobmaier and Bachofner (2018).

Lobmaier and Bachofner (2018) suggest a series of methodological practices to increase the accuracy and reliability of determining a woman's fertile window, claiming the standardized protocol for characterizing women's fertility by Blake et al. (2016) is inadequate. These practices include observing participants for purportedly fertile sessions a considerable time before the LH surge, and using salivary ferning and cervical mucus evaluation as real-time measures of current fertility. Here I explain that Lobmaier and Bachofner's (2018) recommendations decrease rather than increase the likelihood of observing women during peak fertility. I also summarize the pertinent literature on salivary ferning and cervical mucus evaluations, showing that neither method has sufficient sensitivity and specificity to characterize peak fertility. Using meta-analytic data of 10K menstrual cycles, I then show that the protocol provided by Blake et al. (2016) recruits women when conception probability is at its peak and is statistically higher than the window recommended by Lobmaier and Bachofner (2018).

Aggression in Women: Behavior, Brain and Hormones.

We review the literature on aggression in women with an emphasis on laboratory experimentation and hormonal and brain mechanisms. Women tend to engage in more indirect forms of aggression (e.g., spreading rumors) than other types of aggression. In laboratory studies, women are less aggressive than men, but provocation attenuates this difference. In the real world, women are just as likely to aggress against their romantic partner as men are, but men cause more serious physical and psychological harm. A very small minority of women are also sexually violent. Women are susceptible to alcohol-related aggression, but this type of aggression may be limited to women high in trait aggression. Fear of being harmed is a robust inhibitor of direct aggression in women. There are too few studies and most are underpowered to detect unique neural mechanisms associated with aggression in women. Testosterone shows the same small, positive relationship with aggression in women as in men. The role of cortisol is unclear, although some evidence suggests that women who are high in testosterone and low in cortisol show heightened aggression. Under some circumstances, oxytocin may increase aggression by enhancing reactivity to provocation and simultaneously lowering perceptions of danger that normally inhibit many women from retaliating. There is some evidence that high levels of estradiol and progesterone are associated with low levels of aggression. We highlight that more gender-specific theory-driven hypothesis testing is needed with larger samples of women and aggression paradigms relevant to women.

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.