A moral trade-off system produces intuitive judgments that are rational and coherent and strike a balance between conflicting moral values.

How does the mind make moral judgments when the only way to satisfy one moral value is to neglect another? Moral dilemmas posed a recurrent adaptive problem for ancestral hominins, whose cooperative social life created multiple responsibilities to others. For many dilemmas, striking a balance between two conflicting values (a compromise judgment) would have promoted fitness better than neglecting one value to fully satisfy the other (an extreme judgment). We propose that natural selection favored the evolution of a cognitive system designed for making trade-offs between conflicting moral values. Its nonconscious computations respond to dilemmas by constructing "rightness functions": temporary representations specific to the situation at hand. A rightness function represents, in compact form, an ordering of all the solutions that the mind can conceive of (whether feasible or not) in terms of moral rightness. An optimizing algorithm selects, among the feasible solutions, one with the highest level of rightness. The moral trade-off system hypothesis makes various novel predictions: People make compromise judgments, judgments respond to incentives, judgments respect the axioms of rational choice, and judgments respond coherently to morally relevant variables (such as willingness, fairness, and reciprocity). We successfully tested these predictions using a new trolley-like dilemma. This dilemma has two original features: It admits both extreme and compromise judgments, and it allows incentives-in this case, the human cost of saving lives-to be varied systematically. No other existing model predicts the experimental results, which contradict an influential dual-process model.

Attitudes and Laws About Abortion Are Linked to Extrinsic Mortality Risk: A Life-History Perspective on Variability in Reproductive Rights.

Abortion policy is conventionally viewed as a political matter with religious overtones. This article offers a different view. From the perspective of evolutionary biology, abortion at a young age can represent prioritization of long-term development over immediate reproduction, a pattern established in other animal species as resulting from stable ecologies with low mortality risk. We examine whether laws and moral beliefs about abortions are linked to local mortality rates. Data from 50 U.S. states, 202 world societies, 2,596 adult individuals in 363 U.S. counties, and 147,260 respondents across the globe suggest that lower levels of mortality risk are associated with more permissive laws and attitudes toward abortion. Those associations were observed when we controlled for religiosity, political ideology, wealth, education, and industrialization. Integrating evolutionary and cultural perspectives offers an explanation as to why moral beliefs and legal norms about reproduction may be sensitive to levels of ecological adversity.

Visual Preference for Socially Relevant Spatial Relations in Humans and Monkeys.

As a powerful social signal, a body, face, or gaze facing toward oneself holds an individual's attention. We asked whether, going beyond an egocentric stance, facingness between others has a similar effect and why. In a preferential-looking time paradigm, human adults showed spontaneous preference to look at two bodies facing toward (vs. away from) each other (Experiment 1a, N = 24). Moreover, facing dyads were rated higher on social semantic dimensions, showing that facingness adds social value to stimuli (Experiment 1b, N = 138). The same visual preference was found in juvenile macaque monkeys (Experiment 2, N = 21). Finally, on the human development timescale, this preference emerged by 5 years, although young infants by 7 months of age already discriminate visual scenes on the basis of body positioning (Experiment 3, N = 120). We discuss how the preference for facing dyads-shared by human adults, young children, and macaques-can signal a new milestone in social cognition development, supporting processing and learning from third-party social interactions.

The Desirable Dad Hypothesis: Male Same-Sex Attraction as the Product of Selection for Paternal Care via Antagonistic Pleiotropy.

Same-sex attraction, a heritable trait with a reproductive cost, lacks a comprehensive evolutionary explanation. Here we build on a hypothesis invoking antagonistic pleiotropy, which suggests that genes linked to male same-sex attraction remain in the gene pool because they have conferred some fitness advantage to heterosexual men possessing them. We posit the "desirable dad hypothesis," which proposes that alleles linked to male non-heterosexual orientations increase traits conducive to childcare; heterosexual men possessing same-sex attracted alleles are more desirable mating partners as a function of possessing superior paternal qualities. We conducted three studies to test predictions from this hypothesis. Results were consistent with all three predictions. Study 1 (N = 1632) showed that heterosexual men with same-sex attracted relatives were more feminine than men without, as indicated by self-report measures of femininity (η2 = .007), warmth (η2 = .002), and nurturance (η2 = .004 - .006). In Study 2 (N = 152), women rated feminine male profiles as more romantically appealing than masculine ones (d = 0.83)-but less so than profiles possessing a combination of feminine and masculine traits. In Study 3 (N = 153), women perceived feminine male profiles as depicting the best fathers and masculine profiles the worst (d = 1.56): consistent with the idea that femininity is attractive for childcare reasons. Together, these findings are consistent with the idea that sexual selection for male parental care may be involved in the evolution of male same-sex attraction.

Psychometric Characteristics of the Italian Version of the Revised Sociosexual Orientation Inventory.

Sociosexuality refers to the tendency to engage in uncommitted sexual behavior and has been dissected into three domains: sociosexual behavior, attitudes, and desire (Penke & Asendorpf, 2008), which led to the revised Sociosexual Orientation Inventory (SOI-R), which was validated on a German sample. The current research aimed at translating and validating an Italian version (I-SOI-R), administered to three distinct Italian participant groups. In the first sample (N = 710, females = 521, age = 18-59 years), we found evidence for a bifactor model, articulated in a general sociosexuality factor and three specific factors (behavior, attitudes, desire). High internal consistency was established for total and subscale scores, alongside favorable test-retest reliability. A connection was found between relationship status and sociosexual desire, though not gender dependent. We found evidence for test-retest reliability in a second sample (N = 55, females = 37, age 20-58 years). In a third study (N = 305, females = 147, age = 19-60 years), the earlier findings were replicated, further confirming the I-SOI-R's construct, criterion, and nomological validity on an online sample. Combining data from the three studies revealed full configural, metric, and scalar invariance regarding gender. This allowed us to meaningfully compare the observed scores of women and men and replicated the finding that men display higher levels of unrestricted sociosexuality. In conclusion, the I-SOI-R may serve as a valuable tool to assess and enhance sexual health, albeit warranting future research on construct and criterion validity.

Visual Attention to Evolutionarily Relevant Information by Heterosexual Men and Women While Viewing Mock Online Dating Profiles.

The way people create social connections and access information has been altered greatly by technology in recent decades. Online browsing of visual profiles has become a common means for seeking potential partners for both short- and long-term relationships. Little is known, however, about how people prioritize mate quality information while viewing online profiles. Using eye-tracking methods and self-report, this study investigated how people evaluated profile-based facial attractiveness and text-based financial resources information, represented by income and occupation. Heterosexual male and female participants, aged between 18 and 27 years, viewed opposite-sex profiles while their eye-movements were recorded using a remote eye-tracking camera. In line with current theory, resources information had little effect on men's overall attention to women's faces, whereas women's overall attention to men's faces varied depending on the level of income and occupation. Women evaluated men's faces more when income and occupation were low, regardless of attractiveness. Unexpectedly, however, men marginally increased their attention toward unattractive women who showed a high-level of income and more esteemed occupation. Men self-reported a higher interest in women for a short-term relationship and women self-reported a higher interest in men for a long-term relationship. This work provides a foundation to further examine how people browse profile-based information and to investigate the mate selection process, with real-world implications for online dating app users, profile design, and content.

Evolutionary Role of the Female Orgasm: Insights into Mate Choice and Beyond.

The female orgasm remains a subject of extensive debate within evolutionary sciences, primarily due to the absence of a consensus regarding its adaptive function. Some hypotheses propose that it could function as a mechanism for mate selection, possibly linked to reproductive strategies. Studies have observed that lesbian women tend to experience orgasms more frequently than straight women, suggesting a potential link to advantageous partner characteristics. We explored the connection between the female orgasm and mate selection, aiming to ascertain its role as an adaptive tool for mate choice. A total of 939 sexually active Brazilian women (Mage = 28.3 years) engaged in committed relationships participated by completing the Marital Empathy Questionnaire, the Female Sexual Function Index, and evaluations of their partners' attributes. Analysis using structural equation models revealed that higher orgasm scores were positively associated with perceptions of partner kindness, intelligence, good health, physical attractiveness, and empathy. However, the small effect sizes of these associations warrant caution in their interpretation, and no significant association was found for relationship duration, financial prospects, dominance, and masculinity/femininity. Additionally, no differences were found between women in same-sex and other-sex relationships regarding orgasm frequency and its association with partner traits. The findings partially support the mate-choice theory, encompassing both sire-choice and pair-bond hypotheses, suggesting that female orgasm is positively associated with some partner attributes related to genetic quality and the capability for emotional connection and resource investment. Therefore, female orgasm may offer information about the partner that might not be primarily accessed and contribute to relationship maintenance.

Polygamous Interest in a Mononormative Nation: The Roles of Sex and Sociosexuality in Polygamous Interest in a Heterosexual Sample from the UK.

Polygamy is a form of "one-sided" consensually non-monogamous relationship where one person has multiple committed partners, each of whom is only involved with that one person. It was likely a reoccurring feature of ancestral mating that posed adaptive problems for our ancestors. Yet polygamy, and multi-partnering more generally, is understudied in Western cultures, raising questions about the existence of polygamous interest and whether this is calibrated adaptively to personal conditions. In two studies, we examined polygamous interest in two heterosexual online samples from the UK. In Study 1 (N = 393), modest interest was found for polygamous relationships overall. Men were six times more open to polygyny than women, but there was little sex difference in openness to polyandry. Further analysis revealed that all forms of multi-partnering were undesirable relative to singlehood and monogamy; however, consensual multi-partner relationships were less undesirable than non-consensual ones. Sex differences were largest for polygyny and arrangements where men had agreed access to a casual partner alongside a committed one, yet these were two of the most acceptable forms of multi-partnering when men and women's responses were combined. Sociosexuality positively predicted interest in most forms of multi-partnering. Study 2 (N = 735) focused on polygyny and added status-linked traits as predictors. The results of Study 1 were broadly replicated, though the status-linked traits did not predict polygynous interest specifically. Instead, sociosexuality and male intrasexual competitiveness uniquely predicted general interest in multi-partner relationships. Overall, interest in polygamy appears to emerge despite social discouragement and sex differences in interest track the relative costs and benefits associated with it. However, there is no strong evidence that polygamous interest is uniquely calibrated to personal conditions when compared to other forms of multi-partnering.

An Evolutionary Psychological Approach Toward BDSM Interest and Behavior.

Bondage/discipline, Dominance/submission, and Sadism/Masochism (BDSM) have gained increased attention and discussion in recent years. This prevalence is accompanied by a shift in perceptions of BDSM, including the declassification of sadomasochism as a paraphilic disorder. Evolutionary psychology offers a unique perspective of why some individuals are interested in BDSM and why some prefer certain elements of BDSM over others (e.g., dominance versus submission). In this paper, we examine BDSM from an evolutionary standpoint, examining biopsychosocial factors that underlie the BDSM interests and practice. We articulate this perspective via an exploration of: proximate processes, such as the role of childhood experiences, sexual conditioning, and physiological factors; as well as ultimate explanations for power play and pain play dimensions of BDSM, highlighting the potential adaptive advantages of each. While BDSM may not be adaptive in itself, we examine the literature of sex differences in BDSM role preferences and argue that these preferences may stem from the extreme forms of behaviors which enhance reproductive success. In the realm of pain play, we explore the intersection of pain and pleasure from both physiological and psychological perspectives, highlighting the crucial role of psychological and play partner factors in modulating the experience of pain. Finally, we encourage future research in social sciences to utilize evolutionary frameworks to further explore the subject and help alleviate the mystification surrounding BDSM. This multifaceted exploration of BDSM provides valuable insights for clinicians, kink-identified individuals, and scholars seeking to understand the evolutionary perspectives of human sexual behavior and preferences.

Exploring Within-Gender Differences in Friendships Using an Online Social Network.

People tend to befriend others similar to themselves, generating a pattern called homophily. However, existing studies on friendship patterns often rely on surveys that assess the perspective of relatively few participants on their friendships but do not measure actualized friendship patterns. Here, we used data from a large Slovakian online social network to assess the role of gender, age, and body mass index (BMI) in same-gender online connections among more than 400,000 users. We found that age and BMI homophily occurred in both men's and women's same-gender connections, but somewhat more strongly among men's. Yet, as women diverged in BMI, their connections were less likely to be reciprocated. We discuss how the evolutionary legacy of men's coalitional competition (e.g., warfare) and women's mating competition or recruitment of allocare providers might contribute to these patterns in modern same-gender relationships. For example, men's engagement in physical activities may lead to similar formidability levels among their same-gender peers. Altogether, our findings highlight the importance of trait similarity to same-gender friendship patterns.

Parents' Reproductive Concerns and Negativity Toward Their Child Disclosing a Minoritized Sexual Orientation.

Parents often respond negatively when a child discloses their minoritized sexual orientation. We propose that parents' negativity in this context may be shaped by evolutionary concerns regarding their children's reproductive outcomes. We tested relevant hypotheses in a correlational study (Study 1) and two randomized experiments (Studies 2 and 3) that recruited parents with children under age 6 as participants. Study 1 (N = 386; 192 mothers and 194 fathers; 84.68% non-Hispanic White) revealed associations between parents' concerns regarding their children's reproductive outcomes and views toward a child disclosing a lesbian, gay, or bisexual (LGB) orientation in the future. The most negative views were reported by parents with elevated reproductive concerns and pessimistic beliefs about the possibility of reproduction for LGB individuals. Studies 2 (N = 327 mothers; 84.10% non-Hispanic White) and 3 (N = 279 fathers; 81.00% non-Hispanic White) tested whether information about reproductive assistance available to same-gender couples might promote more favorable views toward a child's hypothetical LGB orientation disclosure relative to control information. Parents who received reproductive versus control information reported more positive attitudes toward having an LGB child and toward the LGB community. These effects were statistically mediated by their more optimistic beliefs about the possibility of LGB reproduction. Taken together, this work suggests that reproductive concerns may influence parents' views toward their children's sexual orientation disclosures, and alleviating these concerns may be one way to improve parents' relationships with their sexually diverse children.

Why might animals remember? A functional framework for episodic memory research in comparative psychology.

One of Clayton's major contributions to our understanding of animal minds has been her work on episodic-like memory. A central reason for the success of this work was its focus on ecological validity: rather than looking for episodic memory for arbitrary stimuli in artificial contexts, focussing on contexts in which episodic memory would serve a biological function such as food caching. This review aims to deepen this insight by surveying the numerous functions that have been proposed for episodic memory, articulating a philosophically grounded framework for understanding what exactly functions are, and drawing on these to make suggestions for future directions in the comparative cognitive psychology of episodic memory. Our review suggests four key insights. First, episodic memory may have more than one function and may have different functions in different species. Second, cross-disciplinary work is key to developing a functional account of episodic memory. Third, there is scope for further theoretical elaboration of proposals relating episodic memory to food caching and, in particular, future-oriented cognition. Finally, learning-related functions suggested by AI (artificial intelligence)-based models are a fruitful avenue for future behavioural research.

Mortality risk predicts global, local, and individual patterns of human reproduction.

BACKGROUND: Human reproductive dynamics in the post-industrial world are typically explained by economic, technological, and social factors including the prevalence of contraception and increasing numbers of women in higher education and the workforce. These factors have been targeted by multiple world governments as part of family policies, yet those policies have had limited success. The current work adopts a life history perspective from evolutionary biology: like most species, human populations may respond to safer environments marked by lower morbidity and mortality by slowing their reproduction and reducing their number of offspring. We test this association on three levels of analysis using global, local, and individual data from publicly available databases. RESULTS: Data from over 200 world nations, 3,000 U.S. counties and 2,800 individuals confirm an association between human reproductive outcomes and local mortality risk. Lower local mortality risk predicts "slower" reproduction in humans (lower adolescent fertility, lower total fertility rates, later age of childbearing) on all levels of analyses, even while controlling for socioeconomic variables (female employment, education, contraception). CONCLUSIONS: The association between extrinsic mortality risk and reproductive outcomes, suggested by life history theory and previously supported by both animal and human data, is now supported by novel evidence in humans. Social and health policies governing human reproduction, whether they seek to boost or constrain fertility, may benefit from incorporating a focus on mortality risk.

Two social minds in one brain? error-related negativity provides evidence for parallel processing pathways during social evaluation.

Several authors assume that evaluative conditioning (EC) relies on high-level propositional thinking. In contrast, the dual-process perspective proposes two processing pathways, one associative and the other propositional, contributing to EC. Dual-process theorists argue that attitudinal ambiguity resulting from these two pathways' conflicting evaluations demonstrate the involvement of both automatic and controlled processes in EC. Previously, we suggested that amplitude variations of error-related negativity and error-positivity, two well-researched event-related potentials of performance monitoring, allow for the detection of attitudinal ambiguity at the neural level. The present study utilises self-reported evaluation, categorisation performance, and neural correlates of performance monitoring to explore associative-propositional ambiguity during social attitude formation. Our results show that compared to associative-propositional harmony, attitudinal ambiguity correlates with more neutral subjective evaluations, longer response times, increased error commission, and diminished error-related negativity amplitudes. While our findings align with dual-process models, we aim to offer a propositional interpretation. We discuss dual-process theories in the context of evolutionary psychology, suggesting that associative processes may only represent a small piece of the EC puzzle.

Preliminary evidence for neck musculature in shaping functional stereotypes of men's relationship motives.

Neck musculature is reliably diagnostic of men's formidability and central to several inferences of their physical prowess. These inferences facilitate stereotypes of men's social value from which perceivers estimate their abilities to satisfy reproductive goals related to mate acquisition and parental care. Participants evaluated men's interest in various mating and parenting strategies, wherein men varied in the size of visible neck musculature through trapezii and sternocleidomastoids for perceivers to identify potential reproductive interests and goals. Large trapezii elicited perceptions of men as more effective at protecting offspring, albeit at the expense of nurturance and interest in long-term pair bonds. Results extend previous findings implicating formidability as central to relationship decisions by considering a novel modality.

Harm Hypervigilance in Public Reactions to Scientific Evidence.

Two preregistered studies from two different platforms with representative U.S. adult samples (N = 1,865) tested the harm-hypervigilance hypothesis in risk assessments of controversial behavioral science. As expected, across six sets of scientific findings, people consistently overestimated others' harmful reactions (medium to large average effect sizes) and underestimated helpful ones, even when incentivized for accuracy. Additional analyses found that (a) harm overestimations were associated with support for censoring science, (b) people who were more offended by scientific findings reported greater difficulty understanding them, and (c) evidence was moderately consistent for an association between more conservative ideology and harm overestimations. These findings are particularly relevant because journals have begun evaluating potential downstream harms of scientific findings. We discuss implications of our work and invite scholars to develop rigorous tests of (a) the social pressures that lead science astray and (b) the actual costs and benefits of publishing or not publishing potentially controversial conclusions.

Animals evoking fear in the Cradle of Humankind: snakes, scorpions, and large carnivores.

Theories explain the presence of fears and specific phobias elicited by animals in contemporary WEIRD (Western, educated, industrialized, rich, and democratic) populations by their evolutionary past in Africa. Nevertheless, empirical data about fears of animals in the Cradle of Humankind are still fragmentary. To fill this gap, we examined which local animals are perceived as the most frightening by Somali people, who inhabit a markedly similar environment and the region where humans have evolved. We asked 236 raters to rank 42 stimuli according to their elicited fear. The stimuli were standardized pictures of species representing the local fauna. The results showed that the most frightening animals were snakes, scorpions, the centipede, and large carnivores (cheetahs and hyenas). These were followed up by lizards and spiders. Unlike in Europe, spiders represent less salient stimuli than scorpions for Somali respondents in this study. This conforms to the hypothesis suggesting that fear of spiders was extended or redirected from other chelicerates.

Neural correlates of performance monitoring vary as a function of competition between automatic and controlled processes: An ERP study.

Dual process theories of attitude formation propose that an evolutionary old associative system automatically generates subjective judgments by processing mere spatiotemporal contiguity between paired objects, subjects, or events. These judgments can potentially contradict our well-reasoned evaluations and highjack decisional or behavioral outcomes. Contrary to this perspective, other models stress the exclusive work of a single propositional system that consciously process co-occurrences between environmental cues and produce propositions, i.e., mental statements that capture the specific manner through which stimuli are linked. We constructed an experiment on the premise that it would be possible, if the associative system does produce attitudes in a parallel non-conscious fashion, to condition two mutually exclusive attitudes (one implicit, the other explicit) toward a same stimulus. Through explicit ratings, inhibition performance, and neural correlates of performance monitoring, we assessed whether there was a discrepancy between stimuli that were conditioned with (1) the two systems working in harmony (i.e., producing congruent attitudes), or (2) the two systems working in competition (i.e., producing incongruent attitudes). Compared with congruent stimuli, incongruent stimuli consistently elicited more neutral liking scores, higher response times and error rates, as well as a diminished amplitudes in two well-studied neural correlates of automatic error detection (i.e., error-related negativity) and conscious appraisal of error commission (i.e., error-related positivity). Our findings are discussed in the light of evolutionary psychology, dual-process theories of attitude formation and theoretical frameworks on the functional significance of error-related neural markers.

Erectile Dysfunction, Suspicious Jealousy, and Partner-Directed Behaviors in Heterosexual Romantic Couples.

Erectile dysfunction (ED) can have negative consequences for men and their intimate partners. The purpose of the present research was to replicate and extend the results of previous studies concerning the connections that ED has with partner-directed behaviors using a sample of heterosexual romantic couples. Specifically, we used an actor-partner interdependence mediation model to examine whether the associations that ED had with men's mate retention behaviors, partner-directed insults, partner-directed violence, and partner-inflicted injuries were mediated by suspicious jealousy, but not reactive jealousy. These associations were examined in 113 romantic couples, using men's self-reports, and partner-reports provided by their female partners. Results indicated that suspicious jealousy (but not reactive jealousy) mediated the associations that ED had with men's use of partner-directed behaviors, such that higher levels of ED were associated with men experiencing more suspicious jealousy, which, in turn, was associated with more cost-inflicting mate retention behaviors, benefit-provisioning mate retention behaviors, partner-directed insults, partner-directed violence, and partner-inflicted injury. However, there were some discrepancies between the reports provided by men and women such that these associations emerged more consistently in the partner-reports provided by women than in the self-reports provided by men. Discussion addresses evolutionary implications of these findings, as well as limitations of this research and directions for research concerning ED.

Consistency of Eye Coloration Across Different Relationship Partners.

Studies have indicated that people are attracted to partners who resemble themselves or their parents, in terms of physical traits including eye color. We might anticipate this inclination to be relatively stable, giving rise to a sequential selection of similar partners who then represent an individual's "type". We tested this idea by examining whether people's sequential partners resembled each other at the level of eye color. We gathered details of the eye colors of the partners of participants (N = 579) across their adult romantic history (N = 3250 relationships), in three samples, comprising two samples which made use of self-reports from predominantly UK-based participants, and one which made use of publicly available information about celebrity relationship histories. Recorded partner eye colors comprised black (N = 39 partners), dark brown (N = 884), light brown (N = 393), hazel (N = 224), blue (N = 936), blue green (N = 245), grey (N = 34), and green (N = 229). We calculated the proportion of identical eye colors within each participant's relationship history, and compared that to 100,000 random permutations of our dataset, using t-tests to investigate if the eye color of partners across an individual's relationship history was biased relative to chance (i.e., if there was greater consistency, represented by higher calculated proportions of identical eye colors, in the original dataset than in the permutations). To account for possible eye color reporting errors and ethnic group matching, we ran the analyses restricted to White participants and to high-confidence eye color data; we then ran the analyses again in relation to the complete dataset. We found some limited evidence for some consistency of eye color across people's relationship histories in some of the samples only when using the complete dataset. We discuss the issues of small effect sizes, partner-report bias, and ethnic group matching in investigating partner consistency across time.