Adult individuals frequently face difficulties in attracting and keeping mates, which is an important driver of singlehood. In the current research, we investigated the mating performance (i.e., how well people do in attracting and retaining intimate partners) and singlehood status in 14 different countries, namely Austria, Brazil, China, Greece, Hungary, Italy, Japan, Peru, Poland, Russia, Spain, Turkey, the UK, and Ukraine (N = 7,181). We found that poor mating performance was in high occurrence, with about one in four participants scoring low in this dimension, and more than 57% facing difficulties in starting and/or keeping a relationship. Men and women did not differ in their mating performance scores, but there was a small yet significant effect of age, with older participants indicating higher mating performance. Moreover, nearly 13% of the participants indicated that they were involuntarily single, which accounted for about one-third of the singles in the sample. In addition, more than 15% of the participants indicated that they were voluntarily single, and 10% were between-relationships single. We also found that poor mating performance was associated with an increased likelihood of voluntary, involuntary, and between-relationships singlehood. All types of singlehood were in higher occurrence in younger participants. Although there was some cross-cultural variation, the results were generally consistent across samples.

Sexual double standards are social norms that impose greater social opprobrium onwomen versus men or that permit one sex greater sexual freedom than the other.This study examined sexual double standards when choosing a mate based on theirsexual history. Using a novel approach, participants (N = 923, 64% women) wererandomly assigned to make evaluations in long-term or short-term mating contextsand asked how a prospective partner's sexual history would influence their ownlikelihood of having sex (short-term) or entering a relationship (long-term)with them. They were then asked how the same factors would influence theappraisal they would make of male and female friends in a similar position. Wefound no evidence of traditional sexual double standards for promiscuous orsexually undesirable behavior. There was some evidence for small sexual doublestandard for self-stimulation, but this was in the opposite direction to thatpredicted. There was greater evidence for sexual hypocrisy as sexual historytended to have a greater negative impact on suitor assessments for the selfrather than for same-sex friends. Sexual hypocrisy effects were more prominentin women, though the direction of the effects was the same for both sexes.Overall, men were more positive about women's self-stimulation than women were,particularly in short-term contexts. Socially undesirable sexual behavior(unfaithfulness, mate poaching, and jealous/controlling) had a large negativeimpact on appraisals of a potential suitor across all contexts and for bothsexes. Effects of religiosity, disgust, sociosexuality, and question ordereffects are considered.

The present studies investigated the relationships between men's perceived riskof experiencing sperm competition (i.e., when the ejaculates of two or more mensimultaneously occupy the reproductive tract of a single woman), and their useof strategies to detect, prevent, and correct their partner's sexual infidelity.We investigated these associations using self-reports provided by men (Study 1,n = 113), partner-reports provided by women (Study 2,n = 136), and dyadic reports (Study 3,n = 103 couples). The results of these studies indicated thatthe attractiveness of women was consistently associated with men's use ofbenefit-provisioning mate retention behaviors (e.g., buying expensive gifts forone's partner, showing signs of physical affection) and semen-displacingbehaviors (e.g., deeper copulatory thrusting, more thrusts during copulation),whereas the infidelity risk of women was often associated with men's use ofcost-inflicting mate retention behaviors (e.g., threatening to end therelationship, monopolization of partner's free time). Discussion addresses theevolutionary implications of these results, including the possibility that menuse both benefit-provisioning mate retention behaviors and semen-displacingbehaviors when they perceive their partner to be more attractive, ostensibly asa way to mitigate their risk of sperm competition. Discussion also explores theextent to which these results extend those of previous studies concerning spermcompetition risk.

An ecological approach to social perception states that impressions of faces have functional value in that they guide adaptive behavior ensuring people's survival. For example, people may avoid others whose faces appear sick to avoid an illness representing a survival threat. We broadened the ecological approach in the current work by examining whether merely thinking about what illnesses on faces look like (i.e., how sickness on faces is represented) holds functional value in guiding behavior to ensure survival. Using an example of a real illness threat as proof of concept, we showed that people self-reported performing more adaptive health behaviors in response to COVID-19 if they had sicker representations of COVID-19 on faces (Experiment 1a). These sicker representations of COVID-19 on faces explained, in part, a positive relation between perceptions of COVID-19 as threatening and people's self-reported adaptive health behaviors. We then replicated these patterns when experimentally manipulating illness threat (Experiment 1b). We found that people expected more adaptive health behaviors and had sicker representations of illness on faces in response to illness threats that were more relative to less threatening. These findings suggest that mentally representing sickness on faces is enough to guide people's behaviors in response to illness threats.

This study focuses on determinants underlying young persons" self-reported intentions to steal a small amount of money. From an evolutionary standpoint, theft is a frequency-dependent strategy that may have been favored because it gave individuals a reproductively-relevant advantage in the competition for scarce resources. Although human groups do not tolerate the act of stealing, theft is still very common. Our study is rooted in Robert Frank's theory of the moral commitment problem. Moral emotions such as anticipated guilt are devices designed by evolutionary forces to motivate cooperative behavior in situations entailing a commitment problem. However, the anticipation of guilt feelings can be circumvented by self-serving justifications, therefore increasing the likelihood to steal. A large region-wide sample of adolescents (N = 3694) is used to analyze whether anticipated moral guilt and self-serving justifications mediate the effects of empathy, fear sensitivity, and perceived peer disapproval in their relationship to intentions to steal. Several propositions are tested in a latent variable model within the framework of SEM. Visual scenarios depicting an opportunity to take a small amount of money from a stranger are used to elicit participants" self-reported intentions to steal. Results suggest that empathic concern and empathic perspective-taking, perceived peer disapproval, and fear sensitivity affect the likelihood of theft by influencing anticipated guilt and self-serving justifications that, in turn, respectively reduce and promote the likelihood of theft.

Female orgasm has been a mystery that psychologists have been attempting to understandfor decades. Many have contended that female orgasm is a functionless by-product of maleorgasm, while others have argued that female orgasm may be an adaptation in its own right,offering several adaptationist accounts of female orgasm. In the current research, wetested predictions derived from two hypotheses regarding adaptive functions of femaleorgasm: female orgasm indicates partner mate value or female orgasm promotes long-term,pair bonding. 199 female undergraduates participated in an experiment where they imaginedthemselves as a member of a romantic relationship provided in a scenario. Within thesescenarios, the relationships varied between either short- or long-term and the frequencythat the female experienced orgasm during intercourse varied between never, occasionally,and almost always. Participants answered questions regarding relationship satisfaction andperceptions of the fictional relationship. A series of analysis of variance (ANOVAs)indicated that females assigned to conditions of experiencing more frequent orgasmsreported greater relationship satisfaction, across both short- and long-termrelationships. The relationship between female orgasm frequency and relationshipsatisfaction was fully mediated by the female's perceived love for her hypotheticalpartner but not by perceptions of her hypothetical partner's commitment. Taken together,this study provides preliminary support for the hypothesis that female orgasm evolved as amate-selection tool for females and promotes long-term, pair bonding but does not providesupport for the hypothesis that female orgasm evolved as an indicator of male value.

The aim of the present study was to investigate whether neutral faces of individuals with different propensities for leadership may convey information about their personal qualities, and are there impacts of sex, population and social environment on the facial perception. This study is based on a previous experiment (Rostovtseva et al., 2022), where emergent leadership in the context of male group cooperation was investigated in Buryats (Mongolian population of Siberia). In the previous study three behavioural types of participants were revealed: non-leaders, prosocial leaders and leaders-cheaters, each having a set of distinguishing personality, communicative, and cooperative features. In the current study, three composite portraits representing different leadership qualities of Buryat men from the prior experiment were created. The composites were then scored on a number of traits by male and female Russian and Buryat independent raters (N = 435). The results revealed that ratings on masculinity, physical strength, dominance, competitiveness, and perceived leadership were positively correlated, while perceived trustworthiness was negatively associated with these traits. However, the composite portraits of actual leaders generally were scored as more trustworthy, masculine, and physically strong, with the prosocial leaders’ portrait being perceived as healthier than others. Surprisingly, the composite of leaders-cheaters was scored as the most trustworthy and generous, and the least competitive than others. No significant effects of raters’ sex, origin, or degree of familiarity with Mongolian appearance were revealed. We conclude that static facial morphology contributes to appearing trustworthy, which may allow exploitation of others.

To test the hypothesis that infant night waking is an adaptation to increase interbirth intervals (IBIs) (i.e., the time between a mother’s consecutive births) by exhausting the mother, we made an initial attempt at investigating whether maternal sleep disturbance is associated with longer IBIs. We also explored whether postpartum depression symptoms mediated the association between maternal sleep disturbance and IBI length. We used retrospective self-reports from 729 mothers living in Finland. We conducted structural regressions separately for the mother’s two first children at two different age intervals (0–1 and 1–3 years). Infant night waking was associated with maternal sleep disturbance (β = .78–.84) and maternal sleep disturbance was associated with postpartum depression symptoms (β = .69–.81). Postpartum depression symptoms were also associated with longer IBIs for the first child (β = .23–.28). This result supports the notion that postpartum depression in and of itself could be viewed as adaptive for the offspring’s fitness, and not just as an unintentional byproduct of the mother’s sleep disturbance. Contrary to our prediction, maternal sleep disturbance was, however, associated with shorter IBIs for the first child (β = −.22 to −.30) when including postpartum depression symptoms in the model. We discuss the potential role of social support as an explanation for this unexpected result.

The mate retention inventory (MRI) has been a valuable tool in the field of evolutionary psychology for the past 30 years. The goal of the current research is to subject the MRI to rigorous psychometric analysis using item response theory to answer three broad questions. Do the individual items of the MRI fit the scale well? Does the overall function of the MRI match what is predicted? Finally, do men and women respond similarly to the MRI? Using a graded response model, it was found that all but two of the items fit acceptable model patterns. Test information function analysis found that the scale acceptably captures individual differences for participants with a high degree of mate retention but the scale is lacking in capturing information from participants with a low degree of mate retention. Finally, discriminate item function analysis reveals that the MRI is better at assessing male than female participants, indicating that the scale may not be the best indicator of female behavior in a relationship. Overall, we conclude that the MRI is a good scale, especially for assessing male behavior, but it could be improved for assessing female behavior and individuals lower on overall mate retention behavior. It is suggested that this paper be used as a framework for how the newest psychometrics techniques can be applied in order to create more robust and valid measures in the field of evolutionary psychology.

Based on the neuro-functional association between navigation in the physical and themental space at the level of the hippocampal-entorhinal system, Buzsáki and Moser (2013) have hypothesized aphylogenetic continuity between spatial navigation and declarative memory functions.According to this proposal, mechanisms of episodic and semantic memory would have evolvedfrom mechanisms of self-based and map-based navigation in the physical space,respectively. Using classic versions of path integration and item recognition tasks inhuman subjects, we have recently described a correlation and a predictive relationshipbetween abilities in egocentric navigation and episodic memory. Here we aim at confirmingand extending this association to the dynamic component of sequential updating in thephysical (egocentric navigation) and mental (episodic memory) space, and at investigatingthe relationship of these self-centered abilities with semantic memory. To this aim, wedeveloped three new experimental tasks in which the dynamic component of updatinginformation is particularly emphasized in the spatial, the temporal, and the semanticdomain. The contribution of visual short-term memory to the three tasks was alsocontrolled by including an additional task. The results confirmed the existence of adirect and predictive relationship between self-based spatial navigation and episodicmemory. We also found a significant association between egocentric navigation and semanticmemory, but this relationship was explained by short-term memory abilities and wasmediated by episodic memory functions. Our results support the hypothesis of anevolutionary link between mechanisms that allow spatial navigation in the physical spaceand time travel in the mental space.