The significant role of post-pairing male behavior on the evolution of male preferences and female traits

Existing sexual selection theory postulates that a sufficiently large variation in female fecundity or other direct benefits are fundamental for generating male mate choice. In this study, we suggest that, in addition to pre-pairing preferences, choosy males can also have different post-pairing behaviors, a factor which has been comparatively overlooked by previous studies. We found that both male preferences and female traits could evolve much more easily than previously expected when the choosy males that paired with unpreferred females would allocate more efforts to seeking additional post-pairing mating opportunities. Furthermore, a costly female trait could evolve when there was a trade-off between seeking additional mating and paternal care investment within social pair for choosy males. Finally, a costly male preference and a costly female trait might still evolve and reach a stable polymorphic state in the population, which might give rise to a high variability in male choice and female traits in nature. We suggest that male mate choice may be even more common than expected, which needs to be verified empirically.

The Evolutionary Origin and Biological Utility of Supernatural Expertise

<p>Recent psychological and cognitive research has explored the evolutionary origins of human religiosity. In this thesis, I explore the historical origin and social function of supernatural expertise. I define supernatural expertise as the act of acquiring and expressing supernatural knowledge. I critique several recent theories from evolutionary psychology and cognitive science by assessing the extent to which they can explain supernatural expertise. Costly signalling theory is the view that religious costs are adaptations that signal the cooperative intent of individuals. This theory cannot account for supernatural expertise as expressions of supernatural knowledge are typically linguistic, and one can verbally misrepresent one’s supernatural beliefs. Sexual selection theory explains how physiological or psychological traits can become exaggerated over time if they are preferred by mating partners. Sexual selection can explain an increase in the cognitive capacities necessary for the acquisition of supernatural knowledge. However, it cannot account for the complex nature of supernatural information. Cognitively optimal theory predicts that the religious information which persists within human populations should be easily transferred and recalled. The theory cannot account for any supernatural information which requires considerable effort to acquire. The modes theory explains religion in terms of memory systems and the social arrangements that humans have developed to mediate the exchange of religious ideas. These result in two modes of religiosity. The doctrinal mode of religiosity explains why supernatural experts exist, but not how supernatural expertise originated. I conclude by arguing for an innovative theory for supernatural expertise. I employ cognitively optimal theory to explain why some supernatural concepts are difficult to recall. I explain the signalling function of supernatural expertise in terms of the costly effort invested in the acquisition of supernatural information. I propose that sexual selection for the cognitive capacities to acquire supernatural knowledge has enhanced the ability to acquire such information; this necessitates an increase in the complexity of supernatural information which ensures cooperative commitment remains a predominant motivation for the acquisition of supernatural knowledge, in spite of enhanced cognitive ability. I discuss several social conditions that result from the doctrinal mode of religiosity and how they solve cooperation problems in dense populations.</p>

The Evolutionary Origin and Biological Utility of Supernatural Expertise

<p>Recent psychological and cognitive research has explored the evolutionary origins of human religiosity. In this thesis, I explore the historical origin and social function of supernatural expertise. I define supernatural expertise as the act of acquiring and expressing supernatural knowledge. I critique several recent theories from evolutionary psychology and cognitive science by assessing the extent to which they can explain supernatural expertise. Costly signalling theory is the view that religious costs are adaptations that signal the cooperative intent of individuals. This theory cannot account for supernatural expertise as expressions of supernatural knowledge are typically linguistic, and one can verbally misrepresent one’s supernatural beliefs. Sexual selection theory explains how physiological or psychological traits can become exaggerated over time if they are preferred by mating partners. Sexual selection can explain an increase in the cognitive capacities necessary for the acquisition of supernatural knowledge. However, it cannot account for the complex nature of supernatural information. Cognitively optimal theory predicts that the religious information which persists within human populations should be easily transferred and recalled. The theory cannot account for any supernatural information which requires considerable effort to acquire. The modes theory explains religion in terms of memory systems and the social arrangements that humans have developed to mediate the exchange of religious ideas. These result in two modes of religiosity. The doctrinal mode of religiosity explains why supernatural experts exist, but not how supernatural expertise originated. I conclude by arguing for an innovative theory for supernatural expertise. I employ cognitively optimal theory to explain why some supernatural concepts are difficult to recall. I explain the signalling function of supernatural expertise in terms of the costly effort invested in the acquisition of supernatural information. I propose that sexual selection for the cognitive capacities to acquire supernatural knowledge has enhanced the ability to acquire such information; this necessitates an increase in the complexity of supernatural information which ensures cooperative commitment remains a predominant motivation for the acquisition of supernatural knowledge, in spite of enhanced cognitive ability. I discuss several social conditions that result from the doctrinal mode of religiosity and how they solve cooperation problems in dense populations.</p>

Self-Protection as an Adaptive Female Strategy

Many male traits are well explained by sexual selection theory as adaptations to mating competition and mate choice, whereas no unifying theory explains traits expressed more in females. Anne Campbell's “staying alive” theory proposed that human females produce stronger self-protective reactions than males to aggressive threats because self-protection tends to have higher fitness value for females than males. We examined whether Campbell's theory has more general applicability by considering whether human females respond with greater self-protectiveness than males to other threats beyond aggression. We searched the literature for physiological, behavioral, and emotional responses to major physical and social threats, and found consistent support for females’ responding with greater self-protectiveness than males. Females mount stronger immune responses to many pathogens; experience a lower threshold to detect, and lesser tolerance of, pain; awaken more frequently at night; express greater concern about physically dangerous stimuli; exert more effort to avoid social conflicts; exhibit a personality style more focused on life's dangers; react to threats with greater fear, disgust and sadness; and develop more threat-based clinical conditions than males. Our findings suggest that in relation to threat human females have relatively heightened protective reactions compared to males. The pervasiveness of this result across multiple domains suggests that general mechanisms might exist underlying females’ unique adaptations. An understanding of such processes would enhance knowledge of female health and well-being.

Testing Mate Choice Hypotheses in a Transitional Small Scale Population

Objective Tests of theories of mate choice often rely on data gathered in White, industrialised samples and this is especially the case for studies of facial attraction. Our understanding of preferences for sexual dimorphism is currently in flux and a number of hypotheses require testing in more diverse participant samples. The current study uses opportunistically gathered facial dimorphism preference data from 271 participants in rural Nicaragua, and 40 from the national capital Managua. We assess pre-registered hypotheses drawn from sexual selection theory, and from more recent approaches which consider the impacts of economic development and cultural ‘modernisation’ on mate preferences. Methods Participants verbally reported demographic data, and indicated preferences for five male and five female pairs of faces manipulated to differ in sexually dimorphic facial structure based on a sample of Salvadoran individuals. Results While urban participants showed a preference for more feminine female faces, this preference was not evident in the rural participants. Neither urban nor rural participants showed any directional preference for masculinised/feminised male faces. Furthermore, there was no support for any other pre-registered hypothesis. Conclusions Our results are consistent with previous studies showing no interest in facial dimorphism in less globally-acculturated, or market integrated, populations. Together, this suggests that while facial dimorphism may be subject to systematically varying preferences amongst some low-fertility, industrialised populations, it is not a feature which is likely to have been important in ancestral populations. We call for further work attempting to replicate well known mate choice phenomena in more diverse samples.

Long-term mating positively predicts both reproductive fitness and parental investment

Empirical data on the relations between mating and reproductive success are rare for humans, especially for industrial and post-industrial populations. Existing data show that mating (and especially long-term mating) can be beneficial for fitness, especially that of males. This finding is in line with the hypothesis of sexual selection operating in human populations. The present research expands on previous studies by: 1) analysing additional fitness indicators, including having children with different partners; 2) including parental investment in the analysis as another important marker of sexual selection; 3) analysing several mediators between mating, reproductive fitness and parental investment, i.e. age of first and last reproduction and desired number of children. The data were obtained in 2019 from a sample of parents living in Serbia (N=497). The findings showed that long-term mating (duration of longest partner relationship) was positively related to parental investment and number of offspring and grand-offspring. Furthermore, the link between long-term mating and reproductive success was completely mediated by the age of first reproduction and desired number of children. Short-term mating (number of sexual partners) was marginally positively related to the number of children participants had with different partners and negatively related to parental investment. No sex differences in the link between mating, fitness and parental investment were detected. In general, the signatures of sexual selection were weak in the present data, but those that were detected were in line with sexual selection theory. The present findings provide a deeper insight into the adaptive function of mating and also the mechanism of how mating is beneficial for fitness.

Sexual selection as race making

Charles Darwin's theory of sexual selection, as described in The Descent of Man, and Selection in Relation to Sex (1871), should be viewed as a significant transitional point in the modern expression of race. Unlike earlier race theorists, Darwin proposed that sexual reproduction was not merely a testing ground of racial character, but was itself a causal force that could create new races. His account of race was distinctly modern – viewing race not in terms of blood but as a collection of population-level characteristics. Recognizing this feature of Darwin's sexual-selection theory allows us to situate Darwin's work not solely within the history of evolutionary science, but also within the structures of racism that became the governing principles of modern nation states. In other words, sexual selection is an expression of Michel Foucault's biopolitics, in which political power is exercised by states not through the contracts of liberal governance but through the management of population-level phenomena. Furthermore, by contextualizing sexual selection in this theoretical framework, it becomes possible to more clearly emphasize the importance of race in the rise of modern biopolitics.

3D imaging reveals potential anticipatory responses to increasing intraspecific competition in the Drosophila male reproductive system

Selection favour males that anticipate intraspecific competition levels and develop appropriate competitive traits. In holometabolous insects, larval density can act as an ecological cue of males future intraspecific competition levels while also limiting access to food allocated to sexually selected traits (e.g., testes). To date, however, most studies have been conducted in larval densities that may have little or no relevance to species ecology. Here, we manipulated Drosophila melanogaster larval density based on the natural history of the species and used 3D micro-CT imaging to show a strong modulation of testes volume based on larval density: males from high larval densities generally had larger testes. Conversely, males from high densities tended (albeit not statistically significantly) to have the smallest accessory glands and ejaculatory bulb. Overall, we used micro-CT to measure male reproductive morphology in an ecologically relevant design for which the findings broadly support predictions from sexual selection theory.

Sexual selection theory meets disease vector control: Testing harmonic convergence as a “good genes” signal in Aedes aegypti mosquitoes

Background The mosquito Aedes aegypti is a medically important, globally distributed vector of the viruses that cause dengue, yellow fever, chikungunya, and Zika. Although reproduction and mate choice are key components of vector population dynamics and control, our understanding of the mechanisms of sexual selection in mosquitoes remains poor. In “good genes” models of sexual selection, females use male cues as an indicator of both mate and offspring genetic quality. Recent studies in Ae. aegypti provide evidence that male wingbeats may signal aspects of offspring quality and performance during mate selection in a process known as harmonic convergence. However, the extent to which harmonic convergence may signal overall inherent quality of mates and their offspring remains unknown. Methodology/Principal findings To examine this, we measured the relationship between acoustic signaling and a broad panel of parent and offspring fitness traits in two generations of field-derived Ae. aegypti originating from dengue-endemic field sites in Thailand. Our data show that in this population of mosquitoes, harmonic convergence does not signal male fertility, female fecundity, or male flight performance traits, which despite displaying robust variability in both parents and their offspring were only weakly heritable. Conclusions/Significance Together, our findings suggest that vector reproductive control programs should treat harmonic convergence as an indicator of some, but not all aspects of inherent quality, and that sexual selection likely affects Ae. aegypti in a trait-, population-, and environment-dependent manner.

Darwin's bawdy: the popular, gendered and radical reception of the Descent of Man in the US, 1871–1910

Most studies of the American reception of Darwin have focused on the Origin. The Descent of Man, however, was even more widely read and discussed, especially by those outside the emerging scientific establishment. This essay maps the varied, popular and radical responses to the Descent and suggests that these unauthorized readers helped shape the formation of American scientific institutions (by encouraging scientists to close ranks), as well as ordinary Americans’ perceptions of gender and sex. I argue that the radical – freethinkers, socialists and feminists – embrace of sexual selection theory provides one explanation for naturalists’ scepticism of the theory.