Sexual selection and speciation in the Anthropocene.

Anthropogenic change threatens global biodiversity by causing severe ecological disturbance and extinction. Here, we consider the effects of anthropogenic change on one process that generates biodiversity. Sexual selection (a potent evolutionary force and driver of speciation) is highly sensitive to the environment and, thus, vulnerable to anthropogenic ecological change.

Exposure to female olfactory cues hastens reproductive ageing and increases mortality when mating in male mice.

Theories of ageing predict that investment in reproduction will trade-off against survival and later-life reproduction. Recent evidence from invertebrates suggests that just perceiving cues of a potential mate's presence can reduce lifespan, particularly in males, and that activation of neuroendocrine reward pathways associated with mating can alleviate these effects. Whether similar effects occur in vertebrates remains untested.

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.

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.

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 -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.

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.

Sex differences in sexual attraction for aesthetics, resources and personality across age.

Because sexual attraction is a key driver of human mate choice and reproduction, we descriptively assess relative sex differences in the level of attraction individuals expect in the aesthetic, resource, and personality characteristics of potential mates. As a novelty we explore how male and female sexual attractiveness preference changes across age, using a dataset comprising online survey data for over 7,000 respondents across a broad age distribution of individuals between 18 and 65 years. In general, we find that both males and females show similar distribution patterns in their preference responses, with statistically significant sex differences within most of the traits.

Access to females and early life castration individually extend maximal but not median lifespan in male mice.

Investment in reproduction is predicted to accelerate ageing, but the link between reproductive investment and lifespan can be sex- and context-specific. In mammals, female reproductive costs are linked to pregnancy and lactation, but in males substantial reproductive allocation is required for a range of pre- and post-copulatory reproductive traits. Such traits include male-specific increased body size, olfactory signalling and territory defence-traits often expressed under androgen-dependent control.

Sexual dimorphism in trait variability and its eco-evolutionary and statistical implications.

Biomedical and clinical sciences are experiencing a renewed interest in the fact that males and females differ in many anatomic, physiological, and behavioural traits. Sex differences in trait variability, however, are yet to receive similar recognition. In medical science, mammalian females are assumed to have higher trait variability due to estrous cycles (the 'estrus-mediated variability hypothesis'); historically in biomedical research, females have been excluded for this reason.

Papa Don't Preach? : Using Lies to Expose the Truth about Who Suppresses Female Sexuality.

The suppression of sexuality is culturally widespread, and women's sexual promiscuity, activity, and enjoyment are almost always judged and punished more harshly than men's. It remains disputed, however, to what end people suppress sexuality, and who benefits from the suppression of female sexuality. Different theories predict that women in general, men in general, women's intimate partners, or parents benefit most.

Mating in the absence of fertilization promotes a growth-reproduction versus lifespan trade-off in female mice.

Trade-offs between growth, reproduction, and lifespan constrain animal life histories, leading to evolutionary diversification of life history cycles in different environments. In female mammals, gestation and lactation are expected to impose the major costs of reproduction, driving reproductive trade-offs, although mating also requires interactions with males that could themselves influence life history. Here we show that a male's presence by itself leads to lifelong alterations in life history in female mice.

Condition-Dependent Mutual Mate Preference and Intersexual Genetic Correlations for Mating Activity.

Although mating represents a mutual interaction, the study of mate preferences has long focused on choice in one sex and preferred traits in the other. This has certainly been the case in the study of the costs and condition-dependent expression of mating preferences, with the majority of studies concerning female preference. The condition dependence and genetic architecture of mutual mate preferences remain largely unstudied, despite their likely relevance for the evolution of preferences and of mating behavior more generally.

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.

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.

Female mice seek refuge from castrated males, but not intact or vasectomized males, mitigating a socially-induced glucocorticoid response.

Sexual conflict may be manifested during social interactions, shaping the costs of reproduction in sexually reproducing species. This conflict, and the physical necessity of intromission, can intensify the already costly nature of reproduction for female mammals. To identify and partition the costs that males inflict on females during mating and reproduction, we paired female mice with either other females or castrated, vasectomised, or intact (sham-vasectomised) males, thus manipulating exposure to social mating behavior and costs arising from fertilization.

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.

The Interplay Between Economic Status and Attractiveness, and the Importance of Attire in Mate Choice Judgments.

Desirable characteristics of "opposite sex others," such as physical attractiveness and economic status, can influence how individuals are judged, and this is different for men and women. However, under various social contexts where cues of higher or lower economic status is suggested, sex differences in judgments related to mate choice have not been fully explored. In two studies, ratings of economic status and attractiveness were quantified for male and female targets that were presented under various social contexts.

Man, Woman, "Other": Factors Associated with Nonbinary Gender Identification.

Using a unique dataset of 7479 respondents to the online Australian Sex Survey (July-September 2016), we explored factors relevant for individuals who self-identify as one of the many possible nonbinary gender options (i.e., not man or woman).

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.

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.

Persistent effect of sex ratios on relationship quality and life satisfaction.

Convict transportation to Australia imposed heavily male-biased sex ratios in some areas, altering the convict-era mating market and generating long-running cultural effects that persist to the present day. We test whether convict-era sex ratios have altered marital and overall life satisfaction today, through their persistent effects on gender norms and household bargaining. We find that both women and men are happier, and the happiness gap within married couples is smaller in areas where convict-era sex ratios were heavily male-biased than in areas where sex ratios were historically more even.

Life history evolution, reproduction, and the origins of sex-dependent aging and longevity.

Males and females in many species differ in how they age and how long they live. These differences have motivated much research, concerning both their evolution and the underlying mechanisms that cause them. We review how differences in male and female life histories have evolved to shape patterns of aging and some of the mechanisms and pathways involved.

Male Presence can Increase Body Mass and Induce a Stress-Response in Female Mice Independent of Costs of Offspring Production.

Sexual reproduction in animals requires close interactions with the opposite sex. These interactions may generate costs of reproduction, because mates can induce detrimental physiological or physical effects on one another, due to their interest in maximising their own fitness. To understand how a male's presence influences aspects of female physiology implicated in reproductive costs in mice, independent of offspring production, we paired females with vasectomised, castrated or intact males, or other females.

Sexual Conflict and Gender Gap Effects: Associations between Social Context and Sex on Rated Attractiveness and Economic Status.

Human mate choice research often concerns sex differences in the importance of traits such as physical attractiveness and social status. A growing number of studies indicate that cues to social context, including other people who appear in stimulus photographs, can alter that individual's attractiveness. Fewer studies, however, consider judgements of traits other than physical attractiveness, such as wealth.