A longitudinal analysis of women's salivary testosterone and intrasexual competitiveness

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.

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.

Women’s Intrasexual Competitiveness and Jealousy Across the Ovulatory Cycle: A Hormone-Based Study

Research on social status competition among women suggests that underlying hormonal shifts associated with the ovulatory cycle systematically drive alterations in preferences and behavior. Specifically, it is proposed that the fertile window, marked by heightened estradiol and lower progesterone levels, is related to increased psychological motivation for intrasexual social comparison, leading to increasing competitiveness and jealousy. In this pre-registered, longitudinal study, 257 women provided saliva samples for hormone assays, rated the attractiveness of other women, and self-reported intrasexual competitiveness and jealousy across four testing sessions. Multilevel analyses revealed no compelling evidence for (hormone-related) cycle shifts in intrasexual competitiveness, attractiveness ratings, or jealousy. Rather, women higher in intrasexual competitiveness seem to rate other women as more attractive in general. We discuss how our results contribute to a growing body of literature suggesting that women’s social attitudes and preferences are more stable and less hormonally influenced than previously assumed.

Fertility predicts self-development-oriented competitiveness in naturally cycling women but not hormonal contraceptive users

Objective

A growing body of research has begun investigating the relationship between hormones and female competitiveness. Many researchers have focused on the effect of the menstrual cycle and hormonal contraceptives. Despite many attempts at understanding hormone-behavior associations, contradictory findings have made it difficult to determine the existence of true effects. The aim of the current research was to use a robust methodological design to investigate the effect of fertility probability on four competitive orientations in naturally cycling women and hormonal contraceptive users.

Methods

Using a longitudinal diary study with over 3,900 observations from 21 countries, we explore the effect of fertility probability on four self-report competitive orientations after controlling for menstruation: self-developmental competition, hyper competitiveness, competition avoidance, and lack of interest toward competition.

Results

Using Bayesian estimation for ordinal mixed models, we found that fertility probability was associated with an increase in self-development competitiveness amongst naturally cycling women but not hormonal contraceptive users. We also found weak evidence that hormonal contraceptive users show reduced interest in competing compared to naturally cycling women. There were no other robust effects of fertility or hormonal contraceptive use.

Conclusions

These results suggest that fertility probability is associated with increased fluctuations in self-development competitive motivation and that hormonal contraceptives interfere with this effect. This research contributes to the growing body of literature suggesting that hormonal contraceptives may influence psychology and behavior by disrupting evolved hormonal mechanisms.

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.

Testing the role of testosterone versus estrogens in mediating reproductive transitions in female rhesus macaques

In male vertebrates, testosterone is generally known to coordinate reproductive trade-offs, in part by promoting the transition to the next reproduction at the expense of current parental care. The role of testosterone in reproductive transitions has been little tested in female vertebrates, especially in mammals. The present study sought to fill this gap, by first undertaking an experimental study, in which we identified DHT, androstenediol, and in particular etiocholanolone, as fecal androgen metabolites which reflect serum testosterone concentration in female rhesus macaques (Macaca mulatta). Using concentrations of fecal etiocholanolone as proxy for circulating testosterone, we then conducted a field study on 46 free-ranging rhesus macaques of Cayo Santiago, Puerto Rico, to test if testosterone mediates the trade-off between reproductive transition (a higher chance of reproducing in the next year) and current reproduction (providing more care to current offspring). While the evidence for testosterone was weak, the testing of fecal immunoreactive estrogen metabolites suggested a potential role of estrogen in reproductive trade-offs. We found large individual differences in fecal etiocholanolone concentrations during the early postpartum period that were unexplained even after accounting for sociodemographic factors such as age and dominance rank. Further investigation is needed to understand this variation. Our study suggests that the actions of testosterone in females may not have evolved to fulfil the same role in primate reproductive transitions as it does in males, and we encourage more studies to consider the function of testosterone in reproductive behaviors and life history transitions in females of mammalian taxa.

Female Intrasexual Competition and Its Link to Menopausal Stage, Sex Hormone Levels, and Personality Characteristics

Background: Female intrasexual competition (ISC) represents a unique form of social interaction. It describes behaviors primarily applied to enhance a woman's ability to outcompete other women. Previous research suggests that female ISC is influenced by personality characteristics and sex hormones. Although these factors most likely interact to predict female ISC, no previous study has investigated those factors in parallel in order to link theories from social psychology and biology. Women at the end of the reproductive lifespan represent the ideal study population, as they allow for a controlled hormonal environment.

Materials and Methods: Healthy pre- (N = 53) and postmenopausal (N = 56) women were classified according to the Stages of Reproductive Aging Workshop (STRAW+10) criteria. In the follicular phase (for premenopausal women) or on a random day (for postmenopausal women), questionnaires were administered to assess the general tendency to compete intrasexually and the tendency to compete on appearance, attention/interpersonal success, and competence. Additionally, personality characteristics (neuroticism, extraversion, openness, agreeableness, conscientiousness, and self-esteem) were assessed. On the same day, each subject provided an 8 a.m. saliva sample for estradiol, testosterone, progesterone, and dehydroepiandrosterone sulfate. T-tests tested for between-group differences and separate multiple linear regression models tested for an effect of continuous hormone levels and personality characteristics on ISC. Further models were run, testing for an interaction with menopausal stage.

Results: No group differences in ISC were evident (all p > 0.05). In premenopausal women, estradiol levels positively predicted the competition for attention (β = 2.103, p = 0.022). In postmenopausal women, self-esteem predicted the tendency to compete overall (β = −0.208, p < 0.001), on appearance (β = −0.061, p = 0.01), on competence (β = −0.087, p < 0.001), and on attention/interpersonal success (β = −0.060, p = 0.01).

Discussion: These results, though cross-sectional, suggest that women continue to compete intrasexually in postmenopause, giving rise to new questions about the function of female ISC. If confirmed, the findings will indicate that hormones guide competitiveness in fertile women, whereas self-esteem accounts for individual differences in competitiveness post-reproduction. Particularly the function of postmenopausal ISC warrants further investigation.

Menstrual variation in the acute testosterone and cortisol response to laboratory stressors correlate with baseline testosterone fluctuations at a within- and between-person level

Studies have compared HPA and HPG stress reactivity across the follicular and luteal phases to assess the menstrual impact of estradiol and progesterone fluctuations. Ovulatory shifts in baseline and stressor-induced testosterone among athletic women offer a new framework to explore these responses. Here we investigated menstrual variation in baseline testosterone as a predictor of the acute testosterone and cortisol response to laboratory stressors in female athletes. Using a semi-randomized crossover design, thirty athletic women completed a physical (4 × 6-s bike sprints) and psychological (5 × 2-min cognitive tests with social evaluation) stressor on day seven (D7), 14 (D14), and 21 (D21) of a menstrual cycle. Baseline fluctuations and acute changes in salivary testosterone and cortisol were measured. The D14 testosterone response to both stressors (13.7%) exceeded D7 (7.3%) and D21 (7.0%), whereas cortisol was less responsive on D14 (9.8%) than D7 (13.0%) and D21 (12.0%); all moderate to large effect size differences (p < 0.01). Baseline testosterone, which presented large individual and menstrual variation with a D14 peak, was significantly related (moderate correlations) to testosterone and cortisol stress reactivity on a between-person level. Both outcomes were related (weak correlations) to within-person fluctuations in baseline testosterone, but these effects were mediated by testing day. In conclusion, menstrual variation in baseline testosterone concentration correlated with testosterone and cortisol reactivity to a physical and psychological stressor. Thus, gradients of stressor-induced hormonal change showed some dependency to endogenous testosterone, both individual differences and fluctuations over time, among naturally cycling athletic women.Lay summaryThe female menstrual cycle is accompanied by dramatic shifts in estradiol and progesterone concentration, but less is known about testosterone variability and its role in stress regulation. In this study, menstrual fluctuations in baseline testosterone concentration correlated with acute testosterone and cortisol reactivity to laboratory stressors.

Testosterone reactivity to competition and competitive endurance in men and women

Transient shifts in testosterone occur during competition and are thought to positively influence dominance behavior aimed at enhancing social status. However, individual differences in testosterone reactivity to status contests have not been well-studied in relation to real-time expressions of competitive behavior among men and women. This research tests the association between changes in endogenous testosterone levels during competition and performance in terms of competitive endurance. Participant sex, social presence, and relative status outcomes (e.g., winning vs. losing) are tested as moderators of this relationship. In two studies, men and women (total N = 398) competed in the competitive will task (timed weight-holding) either individually or in the presence of an opponent (Study 1) or as a team with and without the presence of a competitor team (Study 2). Results showed a positive relationship between testosterone reactivity and performance for men, particularly those who won or ranked highest among their group - with increasing testosterone predicting better performance and decreasing testosterone predicting worse performance. For women, the effect only emerged among individuals who competed in dyads and lost. In Study 2, an exploratory mediation analysis revealed that individual differences in trait dominance predicted both testosterone reactivity to competition and task performance, with testosterone reactivity (moderated by sex and status outcome) partially explaining the direct relationship between dominance-related traits and behavior. Our goal was to examine testosterone reactivity in relation to real-time competitive effort and highlight the potential role of this relationship in explaining how individual differences in trait dominance produce competitive behavior.

Does women's anxious jealousy track changes in steroid hormone levels?

Findings for progesterone and anxiety in non-human animals led to the hypothesis that women's interpersonal anxiety will track changes in progesterone during the menstrual cycle. There have been few direct tests of this hypothesis, however. Consequently, we used a longitudinal design to investigate whether interpersonal anxiety (assessed using the anxious jealousy subscale of the relationship jealousy questionnaire) tracked changes in salivary steroid hormones during the menstrual cycle in a large sample of young adult women. We found no evidence for within-subject effects of progesterone, estradiol, their interaction or ratio, testosterone, or cortisol on anxious jealousy. There was some evidence that other components of jealousy (e.g., reactive jealousy) tracked changes in women's cortisol, however. Collectively, these results provide no evidence for the hypothesis that interpersonal anxiety tracks changes in progesterone during the menstrual cycle.

Sex Differences in Mate Retention and Mate Quality Enhancement: The Effect of Facial Sexual Dimorphism Cues on Willingness to Introduce a New Friend to One's Partner

Building on previous studies, we investigated the influence of sexual dimorphism cues on mate retention and mate quality enhancement behaviors. A total of 233 participants were presented with facial photographs with varying sexual dimorphism cues that were generated using computer graphic techniques and were asked to rate their behavior tendencies associated with mate retention and quality enhancement. The results showed that (1) female participants utilized mate retention tactics as a function of the sexual dimorphism cues of targets, whereas male participants showed an overall stronger and indiscriminate tendency for mate retention; (2) female participants rated masculine men as more competent and more generally attractive and tended to introduce them to their own partner, a pattern that was consistent with mate quality enhancement strategies, whereas male participants did not exhibit comparable behaviors. Taken together, these results suggest that masculine and feminine facial cues are important, albeit subtle, to one's reproductive value and are closely associated with mate retention and quality enhancement strategies. Limitations and future directions are also discussed.

Within- and between-person variation in morning testosterone is associated with economic risk-related decisions in athletic women across the menstrual cycle

Literature suggests that women experience ovulatory shifts in risk-taking behaviours across different domains, which might be partly attributed to changes in testosterone (T). Thus, we investigated associations between menstrual variability in T concentrations and economic risk-related decisions among athletic women. Thirty-five women were monitored across three consecutive menstrual cycles. Testing occurred on day seven (D7), 14 (D14) and 21 (D21) following the onset of menses. The morning (7 to 8 am) assessment of salivary T (sal-T) and cortisol (sal-C) was followed by the economic Hawk-Dove game (11 am to 12 pm) played in pairs, where hawk decisions were used to index risk. Morning sal-T concentration increased from D7 to D14, before decreasing on D21 (p < 0.001), representing moderate effect size (ES) changes of 0.6 to 0.8. Morning sal-C did not vary over time. Hawk choices paralleled the sal-T results, being elevated on D14 (p < 0.001) with large ES changes of 1.8. Regression analyses revealed that morning sal-T concentration was positively related (p ≤ 0.01) to the number of hawks chosen between- (beta = 0.47) and within-participants (beta = 0.10) when controlling for training hours and menstrual day. In summary, the risk-related choices of athletic women during a dyadic contest covaried with morning sal-T concentrations across the menstrual cycle. Both outcomes were positively correlated on a within- and between-person level. Confirming the major sources of T variation across the menstrual cycle, whilst discerning its relationship with other risk-related behaviours, would be worthwhile avenues for research.

Do Transgender People Respond According to Their Biological Sex or Their Gender Identity When Confronted With Romantic Rivals?

This study examined the hypothesis that gender identity and biological sex represent independent modules and that transgender individuals respond to romantic rivals in line with their gender identity and not with their biological sex. Additionally, associations of jealousy with intrasexual competitiveness (ISC) and social comparison orientation (SCO) were explored. A total of 134 male-to-female and 94 female-to-male transgender individuals from Greater Buenos Aires, Argentina, responded to a questionnaire. In line with the predictions, female-to-male transgender individuals experienced more jealousy than male-to-female transgender individuals in response to a physically dominant rival, whereas male-to-female individuals experienced more jealousy than female-to-male individuals in response to a physically attractive rival. Regardless of their gender identity, in both groups social-communal attributes were the most jealousy-evoking characteristic. Overall, the results indicate that transgender individuals mainly respond in line with their gender identity and not in line with their biological sex when facing romantic rivals. In addition, transgender individuals high in ISC experienced relatively more jealousy in response to all rival characteristics, whereas SCO was only among male-to-female individuals associated with jealousy.

Trait and state patterns of basolateral amygdala connectivity at rest are related to endogenous testosterone and aggression in healthy young women

The steroid hormone testosterone (T) has been suggested to influence reactive aggression upon its action on the basolateral amygdala (BLA), a key brain region for threat detection. However, it is unclear whether T modulates resting-state functional connectivity (rsFC) of the BLA, and whether this predicts subsequent aggressive behavior. Aggressive interactions themselves, which often induce changes in T concentrations, could further alter BLA rsFC, but this too remains untested. Here we investigated the effect of endogenous T on rsFC of the BLA at baseline as well as after an aggressive encounter, and whether this was related to behavioral aggression in healthy young women (n = 39). Pre-scan T was negatively correlated with basal rsFC between BLA and left superior temporal gyrus (STG; p < .001, p < .05 Family-Wise Error [FWE] cluster-level corrected), which in turn was associated with increased aggression (r = .37, p = .020). BLA-STG coupling at rest might thus underlie hostile readiness in low-T women. In addition, connectivity between the BLA and the right superior parietal lobule (SPL), a brain region involved in higher-order perceptual processes, was reduced in aggressive participants (p < .001, p < .05 FWE cluster-level corrected). On the other hand, post-task increases in rsFC between BLA and medial orbitofrontal cortex (mOFC) were linked to reduced aggression (r = -.36, p = .023), consistent with the established notion that the mOFC regulates amygdala activity in order to curb aggressive impulses. Finally, competition-induced changes in T were associated with increased coupling between the BLA and the right lateral OFC (p < .001, p < .05 FWE cluster-level corrected), but this effect was unrelated to aggression. We thus identified connectivity patterns that prospectively predict aggression in women, and showed how aggressive interactions in turn impact these neural systems.

Measuring female intrasexual competition by the scale for intrasexual competition: a validation of the German version

Competitive behaviour amongst members of the same sex is termed intrasexual competition. The tendency to engage in such competition appears to be strongly related to stable individual characteristics such as personality traits. Additionally, recent studies have revealed transient fluctuations in competitiveness according to the female menstrual cycle. To date, no German questionnaire exists to measure intrasexual competition. Our first study aimed to translate and validate the Intrasexual Competition Scale (ICS) by Buunk and Fisher (J Evol Psychol 7:37-48, 2009) in a population of healthy Swiss females (n = 241). Our second study applied the validated German ICS in a group of healthy, regularly cycling females (n = 49) in order to examine possible associations between the menstrual cycle phase and ICS scores. The psychometric properties suggest that the German ICS is a reliable and valid tool to assess individual differences in female intrasexual competition. Furthermore, our second study demonstrated that on average, women showed higher intrasexual competition scores when tested in the late follicular phase (M = 35.77 ± SD = 12.03) compared to the mid-luteal phase (M = 30.93 ± SD = 10.20). Our studies support previous findings of an association between ICS scores and relatively stable individual characteristics such as personality traits. Furthermore, our research endorses the assumption of cycle-dependent fluctuations in intrasexual competition. Future research should clarify the precise mechanisms underlying these findings and include biomarkers such as oestrogen and testosterone.

Sleep restriction alters reactive aggressive behavior and its relationship with sex hormones

Few studies have experimentally manipulated sleep to study its effect on aggressive behavior. The current study examined how reactive aggression was affected by having sleep restricted to 4-hours on a single night, a level of disruption commonly experienced. Both rested and sleep-restricted participants completed the Point Subtraction Aggression Paradigm (PSAP), a laboratory task in which participants seek to earn points, are provoked by a fictitious opponent stealing their points, and may choose to steal points in response. Logistic mixed-effect models were used to investigate the effect of sleep restriction and the role of sex hormones on the odds of choosing to steal. For men, and women in the luteal phase of the menstrual cycle, sleep restriction did not result in significant changes reactive aggression, although the patterns of aggressive behavior appeared less reactive and retaliatory in nature. For women in the follicular phase of the menstrual cycle, sleep restriction was associated with higher levels of reactive aggression. For both men and women in the luteal phase, sleep restriction disrupted an association between hormone change over the task (testosterone and estradiol, respectively) and reactive aggression that was observed in their control participants. In addition, higher testosterone before the PSAP in men was associated with maintaining a high level of stealing over the task. These results indicate a complex dynamic in which sex hormones and sleep interact to predict aggressive behavior in response to provocation.

No Evidence for Associations between men's Salivary Testosterone and Responses on the Intrasexual Competitiveness Scale

Objectives

Many previous studies have investigated relationships between men’s competitiveness and testosterone. For example, the extent of changes in men’s testosterone levels following a competitive task predicts the likelihood of them choosing to compete again. Recent work investigating whether individual differences in men’s testosterone levels predict individual differences in their competitiveness have produced mixed results.

Methods

In light of the above, we investigated whether men’s (N = 59) scores on the Intrasexual Competitiveness Scale were related to either within-subject changes or between-subject differences in men’s salivary testosterone levels.

Results

Men’s responses on the Intrasexual Competitiveness Scale did not appear to track within-subject changes in testosterone. By contrast with one recent study, men’s Intrasexual Competitiveness Scale also did not appear to be related to individual differences in testosterone.

Conclusions

Our results present no evidence for associations between men’s testosterone and their responses on the Intrasexual Competitiveness Scale.

Electronic supplementary material

The online version of this article (10.1007/s40750-018-0095-2) contains supplementary material, which is available to authorized users.

A longitudinal analysis of salivary testosterone concentrations and competitiveness in elite and non-elite women athletes

BACKGROUND

There is evidence linking women's testosterone (T) to competitive behaviours in sport and exercise. To advance this work, we examined the longitudinal relationships between salivary T (sal-T) and competitiveness in athletic women who differ in training status.

METHODS

Elite (n = 9) and non-elite (n = 21) women athletes were monitored on days 6-8 (follicular phase), 13-15 (ovulatory phase) and 20-22 (Luteal phase) of a menstrual cycle with two repeats. Salivary T levels were assessed before breakfast, followed by two questions (each rated on a 1-7 scale) on competitive desire and training motivation. Using a linear mixed model, we evaluated the menstrual phase and training status effects on each variable, before assessing the within-subject effects of sal-T on competitiveness.

RESULTS

Salivary T concentrations were higher at ovulation (effect size [ES] difference = 0.2-1.4), relative to the follicular and luteal phases, with a more marked response among elite women (p < .01). The competitiveness ratings showed similar menstrual-phase variation (ES difference = 0.6-1.0 at ovulation). A positive effect of sal-T on competitiveness emerged in both groups (p < .001), but with different slope patterns (p < .015). Specifically, the elite sal-T relationships with desire to compete (standardized β = 1.147, SE = 0.132) and training motivation (β = 1.195, SE = 0.124) were stronger compared with non-elite women (β = 0.631, SE = 0.114; β = 0.778, SE = 0.114), respectively.

CONCLUSIONS

Morning sal-T concentrations, competitive desire and training motivation all peaked around ovulation in women athletes. Notably, sal-T availability and its relationship with competitiveness was stronger among high-performing athletes. Our findings confirm menstrual fluctuations in T and competitiveness among naturally-cycling women, with population context as a moderating factor.

Interactions between observer and stimuli fertility status: Endocrine and perceptual responses to intrasexual vocal fertility cues

Both men and women find female voices more attractive at higher fertility times in the menstrual cycle, suggesting the voice is a cue to fertility and/or hormonal status. Preference for fertile females' voices provides males with an obvious reproduction advantage, however the advantage for female listeners is less clear. One possibility is that attention to the fertility status of potential rivals may enable women to enhance their own reproductive strategies through intrasexual competition. If so, the response to having high fertility voices should include hormonal changes that promote competitive behavior. Furthermore, attention and response to such cues should vary as a function of the observer's own fertility, which influences her ability to compete for mates. The current study monitored variation in cortisol and testosterone levels in response to evaluating the attractiveness of voices of other women. All 33 participants completed this task once during ovulation then again during the luteal phase. The voice stimuli were recorded from naturally cycling women at both high and low fertility, and from women using hormonal birth control. We found that listeners rated high fertility voices as more attractive compared to low fertility, with the effect being stronger when listeners were ovulating. Testosterone was elevated following voice ratings suggesting threat detection or the anticipation of competition, but no stress response was found.

Functional significance of men's testosterone reactivity to social stimuli

Rapid testosterone fluctuations in response to social stimuli are observed across a wide range of species, and the highly conserved nature of these fluctuations suggests an adaptive function. This paper reviews the current literature on testosterone reactivity, primarily in human males, and illustrates how life-history theory provides an adequate theoretical framework to interpret findings. The review is structured around supporting evidence suggesting that situations implicated in mating effort either directly (e.g., interactions with a mate) or indirectly (e.g., intrasexual competition) are generally associated with a brief elevation of testosterone, while situations implicated in parenting effort (e.g., nurturant interactions with offspring) are generally associated with a decline in testosterone. Further, we discuss how these fluctuations in testosterone have been linked to future behaviors, and how situational, motivational, and physiological variables moderate the interplay between social stimuli, testosterone reactivity, and behavior. Supporting the notion that testosterone can play a causal role in modulating behavior in response to social stimuli, we also summarize recent single administration studies examining the effects of testosterone on physiology, neurobiology, and behavior. A conceptual model provides links between supported findings, and hypothesized pathways requiring future testing.

Effects of stress on women's preference for male facial masculinity and their endocrine correlates

Women's preferences for masculinity in men's faces seem to vary across the menstrual cycle and are assumed to be strongest around ovulation. A number of hormones have been proposed to underlie these subtle cyclic shifts. Furthermore, mating preferences are context-dependent, and stress has been found to alter mate choice, both in animals and humans. Currently, the effects of stress on women's preference for masculinity remain unknown. To examine the hormonal basis and the impact of stress on facial masculinity preference, we tested for within-subject changes in 52 healthy young women who underwent the Trier Social Stress Test (TSST) and the placebo-TSST in randomized order in the late follicular and mid-luteal phases of their menstrual cycle. Menstrual cycle phase and hormone levels were confirmed using estradiol, testosterone, progesterone, and cortisol analyses from saliva. Results show that women were more likely to be attracted to masculine-faced men right before ovulation than in the mid-luteal phase. Estradiol modulated this masculinity preference with high estradiol levels being related to stronger masculinity preference. When stressed however, women experienced a decrease in male facial masculinity preference. In line with these findings, the higher the cortisol increase to stress, the less were masculine faces preferred to more feminine faces. Mate choice is a central component of reproduction. The present results provide information about the effects of stress and hormonal influences on mate preferences in women.

Hormonal underpinnings of status conflict: Testosterone and cortisol are related to decisions and satisfaction in the hawk-dove game

A contribution to a special issue on Hormones and Human Competition.Testosterone is theorized to influence status-seeking behaviors such as social dominance and competitive behavior, but supporting evidence is mixed. The present study tested the roles of testosterone and cortisol in the hawk-dove game, a dyadic economic decision-making paradigm in which earnings depend on one's own and the other player's choices. If one person selects the hawk strategy and the other person selects the dove strategy, the player who selected hawk attains a greater financial pay-off (status differentiation). The worst financial outcome occurs when both players choose the hawk strategy (status confrontation). Ninety-eight undergraduate students (42 men) provided saliva samples and played ten rounds of the hawk-dove game with another same-sex participant. In support of the hypothesis that testosterone is related to status concern, individuals higher in basal testosterone made more hawk decisions - decisions that harmed the other player. Acute decreases in cortisol were also associated with more hawk decisions. There was some empirical support for the dual-hormone hypothesis as well: basal testosterone was positively related to satisfaction in the game among low basal-cortisol individuals but not among high basal-cortisol individuals. There were no significant sex differences in these hormonal effects. The present findings align with theories of hormones and status-seeking behavior at the individual level, but they also open up new avenues for research on hormone profiles at the collective level. Our results suggest that the presence of two or more high-testosterone members increases the likelihood of status confrontations over a limited resource that can undermine collective outcomes.

Preliminary evidence that acute stress moderates basal testosterone's association with retaliatory behavior

A contribution to a special issue on Hormones and Human Competition. Testosterone is theorized to increase retaliation after social provocation. However, empirical evidence in support of these theories is mixed. The present research investigated whether acute stress causally suppresses testosterone's association with retaliation. We also explored sex differences in behavioral responses to acute stress. Thirty-nine participants (51.28% male) were randomly assigned to a high- or low-stress condition. Then participants engaged in 20 one-shot rounds of the ultimatum game, which was used to assess retaliatory behavioral responses to unfair treatment. Participants provided two saliva samples to measure testosterone and cortisol concentrations - one sample before the stress manipulation, and the second after the ultimatum game (20minutes post-stressor). Results revealed a positive association between basal testosterone and retaliation in the low-stress condition, but not in the high-stress condition. Further, cortisol concentrations increased in the high- compared to the low-stress condition, and these cortisol changes moderated the association between basal testosterone and retaliation. The associations between basal testosterone and retaliation under varying levels of stress were similar in men and women. However, there was a sex difference in behavioral responses to the stress manipulation that was independent of testosterone. In women, the high-stress condition reduced retaliation compared to the low-stress condition, whereas in men the opposite pattern emerged. Collectively, this study (i) provides preliminary evidence that experimentally manipulated stress blocks basal testosterone's association with retaliation, and (ii) reveals a sex difference in retaliation under varying levels of stress. Discussion focuses on mechanisms, limitations, and the need for follow-up studies with larger sample sizes.

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.

High estradiol and low progesterone are associated with high assertiveness in women

Sexual selection theory posits that women are more selective than men are when choosing a mate. This evolutionary theory suggests that "choosiness" increases during the fertile window because the costs and benefits of mate selection are highest when women are likely to conceive. Little research has directly investigated reproductive correlates of choice assertion. To address this gap, in the present research we investigated whether fertility, estradiol, and progesterone influenced general assertiveness in women. We recruited 98 naturally cycling, ethnically diverse women. Using a within-subjects design and ovarian hormone concentrations at fertile and non-fertile menstrual cycle phases, we measured implicit assertiveness and self-reported assertive behavior. To see if fertility-induced high assertiveness was related to increased sexual motivation, we also measured women's implicit sexual availability and interest in buying sexy clothes. Results showed that high estradiol and low progesterone predicted higher assertiveness. Sexual availability increased during periods of high fertility. Low progesterone combined with high estradiol predicted greater interest in buying sexy clothes. Results held when controlling for individual differences in mate value and sociosexual orientation. Our findings support the role of fluctuating ovarian hormones in the expression and magnitude of women's assertiveness. High assertiveness during the fertile window may be a psychological adaptation that promotes mate selectivity and safeguards against indiscriminate mate choice when conception risk is highest.

Power and Autistic Traits

Autistic traits can help people gain and sustain power, and has probably done so throughout history, says the present paper. A number of testable claims follow from this assumption. First, the powerful should have more autistic traits than others - which they do appear to have. Among other things, powerful people, and those with many autistic traits, tend to prefer solitary activities and are often aloof. Moreover, they are often rigid and socially insensitive, low on empathy and with low scores on the trait of agreeableness - and as a rule they do not have many friends. Both groups are also more self-centered than others, more honest, less submissive, more sensitive to slights, and with a stronger tendency to engage in abstract thinking. They tend to behave in bossy or dominant ways, and their moral judgment is more based on rules than on feelings. In addition to experimental evidence, I cite biographies showing that a surprising number of presidents, prime ministers and other powerful people seem to have had traits like those in question - and interestingly, in animals, leaders are often rigid and insensitive to group members' needs and feelings, mostly acting the way they are themselves inclined to, not responding much to others. Problem solving is important in leadership, and people with many autistic traits appear often to be better thinkers than typical subjects with similar IQs. However, these and other congruities could be coincidences. Hence the question of whether traits the two groups have in common also have a common cause constitutes a strong test of the paper's thesis - and a common cause does appear to exist, in the form of testosterone's effects on the central nervous system. Finally, there is evidence that, other things equal, powerful men have more reproductive success than others. If men wielding power do indeed have more autistic traits than those less powerful, this will lead to, other things equal, such traits becoming more common - which can help explain the prevalence of autistic traits.

Testosterone, cortisol, and human competition

Testosterone and cortisol figure prominently in the research literature having to do with human competition. In this review, we track the history of this literature, concentrating particularly on major theoretical and empirical contributions, and provide commentary on what we see as important unresolved issues. In men and women, athletic competition is typically associated with an increase in testosterone (T) and cortisol (C). Hormone changes in response to non-athletic competition are less predictable. Person (e.g., power motivation, mood, aggressiveness, social anxiety, sex, and baseline levels of T and C) and context (e.g., whether a competition is won or lost, the closeness of the competition, whether the outcome is perceived as being influenced by ability vs. chance, provocations) factors can influence hormone responses to competition. From early on, studies pointed to a positive relationship between T and dominance motivation/status striving. Recent research, however, suggests that this relationship only holds for individuals with low levels of C - this is the core idea of the dual-hormone hypothesis, and it is certain that the broadest applications of the hypothesis have not yet been realized. Individuals differ with respect to the extent to which they embrace competition, but the hormonal correlates of competitiveness remain largely unexplored. Although rapid increases in both T and C associated with competition are likely adaptive, we still know very little about the psychological benefits of these hormonal changes. Administration studies have and will continue to contribute to this inquiry. We close with a discussion of what, we think, are important methodological and mechanistic issues for future research.