Adaptive Human Behavior and Physiology最新文献

Purpose

Sexual attraction to males or females is perhaps the largest behavioral sex difference across animal species. Experiments in laboratory mammals show that prenatal androgens mediate this sex difference, but ethical considerations preclude such experimentation in humans. Multiple lines of converging correlational evidence are therefore needed to demonstrate such mediation in humans.

Methods

We review available data linking human sexual orientation to endocrine action, including research on endocrine disorders and biomarkers of early sex hormones. We also perform a meta-analysis across 13 studies comprising 56,804 individuals to investigate a possible link between non-heterosexuality and polycystic ovary syndrome (PCOS), an endocrine condition associated with elevated androgens in females.

Results and conclusions

We find converging evidence that prenatal gonadal hormones influence the development of human sexual orientation and orchestrate its sexual differentiation primarily by regulating patterns of gene expression in the developing brain. Evidence is particularly strong that androgens increase sexual attraction to females. In our meta-analysis, PCOS was more common in non-heterosexual females (r = 0.18, p < 0.001). Some evidence also indicates that estrogens increase sexual attraction to males. We discuss why data may be less clear regarding variation in sexual orientation among males, including the possible existence of subgroups characterized by distinct biological pathways that contribute to same-sex sexual orientation. Moving forward, we propose that multiple measures and/or markers be considered together to better characterize early hormonal action on human sexual orientation.

Men’s beardedness is a sexually dimorphic trait that has played a role in both inter- and intra-sexual selection. It has been suggested that women may prefer bearded men because it may be a cue to men’s underlying physiology and immune function. Beardedness has also been implicated in perceptions of men’s aggressiveness and dominance. In the current research, we explored preferences for men’s beardedness among Iranian and Hispanic women and whether those preferences were moderated by trait pathogen proneness. In Study 1, Hispanic women were recruited and asked to choose the beard profile, from clean-shaven to very long, on a variety of traits (i.e., attractiveness, masculinity, fighting ability, reliable partner, and suitable father). Women more frequently chose light and moderate-length beard types across all outcome measures, and their self-reported levels of disgust was associated with higher preferences for clean-shaven profiles. In Study 2, Hispanic and Iranian women were recruited and asked to rate the beard profiles across the measures. Compared to Iranian women, Hispanic women demonstrated a stronger preference for bearded men. Further, there were cultural differences in self-reported measures of disgust and their preferences for beards in men. The findings from the current study highlight the unique preferences across populations for bearded profiles in men, and they suggest that they may be associated with pathogen trait levels.

Objectives and Method

Anecdotal reports indicate more severe psychological distress following technological catastrophes in comparison to natural disasters. Previous research also suggests a more negative evaluation of the outcomes of disasters if they are manmade. On the other hand, evolutionary neuroscience shows differential neural processing of ancient and modern threats. Building upon this literature, we probed valence and arousal ratings of stimuli depicting natural and technological disasters in several standardized affective stimuli datasets used in neuroscience and psychological research.

Results

Our results show that while technological disasters are rated as slightly less arousing than natural disasters they are rated as significantly more unpleasant.

Conclusion

It seems the evolutionary age of disasters is one of the factors that affect emotional experiences evoked by these threats and can impact our evaluations of catastrophes. We discuss how evolutionary psychology might explain our findings and help us to better understand the biological and learned roots of our biases in risk perception.

Purpose

Women have evolved to conceal overt signs of ovulatory status. Evidence shows that men find high fertility women to be more attractive than low fertility women, suggesting that men may be sensitive to subtle cues to fertility. However, studies have yet to explain the variance in men’s sensitivity to such cues. The present study aimed to identify psychological variables that predict men’s preferences for ovulatory cues in women’s faces in an attempt to provide support for or against three hypotheses for concealed ovulation: The Paternal Investment Hypothesis, The Reduced Infanticide Hypothesis, and the Cuckoldry Hypothesis. We also tested whether men with lower sociosexual orientation show a higher preference for cues to ovulation than men with a higher sociosexual orientation.

Methods

Heterosexual men (N = 182) completed a survey that assessed levels of various mating market traits, which were used to predict scores on a face preference task comprised of fertile-phase and non-fertile-phase images of the same women.

Results

Although men did prefer the faces of women near ovulation more than when they were photographed at other times of the menstrual cycle, the three main hypotheses tested were not supported. However, sociosexuality did negatively predict preference for the high-fertility faces among single participants.

Conclusion

The findings suggest that single men who are lower in sociosexuality may benefit from discriminating between fertile and non-fertile women. Future research directions regarding different ovulatory cue stimuli and mechanisms of cue detection are discussed.

In my response to Costello and Buss’ “Why Isn’t There More Incel Violence”, I address our disagreement over whether the incel movement engages in simulated coalitional bargaining and present an alternative hypothesis regarding suicidal ideation among incels.

Purpose

This study examined associations of older men’s and women’s retired status with their biological age acceleration, and mediation of these linkages by depressive symptoms.

Methods

Data were from the 2010–2016 waves of the Health and Retirement Study, nationally representative of older U.S. adults. Age acceleration was proxied through newly available epigenetic measures. Doubly robust estimation was used to establish baseline linkages, and heterogenous treatment effect models to examine variations in effects by one’s increasing propensity to be retired. Mediation analysis was through a recently developed regression-with-residuals (RWR) approach for structural nested mean models.

Results

Six years after treatment assessment, women retired at baseline showed faster aging than those fully employed. Retired men’s subsequent depressive symptoms were lower, with sparse results also supporting their slower senescence. Associations did not significantly change with increasing propensity for being retired, for either gender.

Conclusion

Results provide novel evidence for retirement’s gender-specific senescence effects. Potential lifestyle mechanisms remain unexplored. Individual and policy implications are discussed.

Incels (involuntary celibates) are an online subculture community of men who form an identity around their perceived inability to form sexual or romantic relationships. They attribute their lack of success to genetic factors, evolved mate preferences, and social inequities. While we have a deep ancestral history of incels, the modern incel community is an evolutionarily novel group that fosters a shared victimhood identity. We applaud Lindner for an important contribution to the scant literature on incels and highlight the importance of her evolutionary psychological lens in understanding their grievances. Our critique of Lindner’s work addresses two key issues. Firstly, we challenge the hypothesis that incels engage in simulated coalitional bargaining for sexual access. While coalitional bargaining for sexual access may have played a role in ancestral populations of involuntarily celibate men, this is not a suitable analysis of modern incels. Instead, the incel community operates as a fatalistic echo-chamber, where failure is celebrated, and individuals discourage each other from pursuing romantic success. Secondly, we critique the association between incels and violence. Contrary to common beliefs, empirical evidence suggests that incels are not particularly prone to violence. Incels’ propensity for violence appears relatively low compared to that of the general population. We conclude by offering one hypothesis as to why modern day incels are not as violent as we might expect. The Male Sedation Hypothesis, that online virtual worlds, such as pornography, may pacify the potential for violence among sexless young men, providing a counterfeit sense of sexual fulfillment and reducing motivation for real-life mate competition.

Objectives

Mass shooters, violent extremists, and terrorists, who are overwhelmingly male, exhibit misogynistic attitudes and a history of violence against women. Over the past few years, incels (“involuntary celibates”) have gathered in online communities to discuss their frustration with sexual/romantic rejection, espouse male supremacist attitudes, and justify violence against women and men who are more popular with women. Despite the link between misogyny and mass violence, and the recent emergence of online misogynistic extremism, theories and empirical research on misogynistic extremism remain scarce. This article fills this gap.

Methods

An integration of literatures pertaining to the basics of sexual selection, evolved male psychology, and aggression suggests there are three major areas that should be considered imperative in understanding the emergence of misogynistic extremism.

Results

Individual factors (e.g., low status) and social forces, such as a high degree of status inequality, female empowerment, and the ease of coordination through social media, give rise to misogynistic extremism.

Conclusions

The unique interaction between evolved male psychology, the dynamics of the sexual marketplace, and modern technologies can create an ecology in which incel beliefs can thrive and make violence attractive.

Objectives

College students adjusted to a unique learning environment under the pressures of the COVID-19 pandemic. Living on campus and participating in “hybrid” instruction demands, individuals experienced contexts that were often socially and psychologically demanding, with potential physiological implications. In this exploratory analysis, we tested for correlations between perceived psychosocial stress and potential stress-buffering processes with fingernail cortisol, a relatively new method for measuring cumulative cortisol production in prior months. We specifically drew on data collected from a small sample of university undergraduates living on campus during a pandemic-affected semester.

Methods

We conducted this study in the Spring of 2021 with University of Notre Dame undergraduate students (age 18–21 years, n = 41). We collected data on participants’ cortisol in the 3–5 months prior through sampling of fingernails. We also collected demographic, disposition, and psychosocial data, including participants’ perceived psychosocial stress, social support, sense of school membership, and satisfaction with the university’s COVID-19 response.

Results

We found non-significant positive associations for nail cortisol with recent perceived stress and neuroticism. Students had (non-significantly) lower nail cortisol if they reported greater social support or higher self-compassion. Finally, participants who were more satisfied with the university’s COVID-19 program had significantly lower nail cortisol. The 95% confidence intervals for these findings were wide and generally included zero, indicating imprecision in our data.

Conclusions

In this exploratory study, we found associations between participants’ fingernail cortisol that align in the predicted directions for using nail cortisol as a stress-related biomarker. The effect sizes for our results are small but are generally comparable to those for chronic stress and cortisol measured through other methods. Given the wide confidence intervals for our results, the findings should be considered preliminary. They may highlight the potential of investigating the role of fingernail cortisol as an indicator of chronic stress activation.

Purpose

Facial femininity in men is purportedly used as a cue by women as a signal of paternal involvement. However, evidence for this claim is questionable. Previous findings have shown that paternal involvement is linked to testosterone, but have not investigated facial masculinity directly, while other studies have found that facial masculinity is negatively associated with perceptions of paternal involvement but do not assess the accuracy of this judgement. Here, we assess whether facial masculinity in men is used as a cue to paternal involvement, and whether this cue is accurate.

Methods

We collected facial photographs of 259 men (156 of which were fathers) who also completed self-report measures of paternal involvement. Facial images were then rated by a separate group of raters on facial masculinity, attractiveness, and perceived paternal involvement. Shape sexual dimorphism was also calculated from the images using geometric morphometrics.

Results

We found that facial masculinity was not associated with perceptions of paternal involvement, nor was it related with self-reported paternal involvement. Interestingly, facial attractiveness was negatively associated with perceptions of paternal involvement, and we found partial evidence that facial attractiveness was also negatively associated with self-reported paternal involvement.

Conclusion

These findings challenge the hypothesis that sexual dimorphism is used as a cue to paternal involvement, and perhaps indicate that facial attractiveness is more important for this judgement instead.