The reality and evolutionary significance of human psychological sex differences

Paradoxical gender effects in meat consumption across cultures

Men tend to eat more meat than women, but it is not clear why. We tested three hypotheses in a cross-cultural design (20,802 individuals in 23 countries across four continents): that gender differences are (a) universal, (b) related to gender roles and thus weaker in countries with higher gender equality and human development, or (c) related to opportunities to express gender roles and thus stronger in countries with higher gender equality and human development. Across all countries, men tended to consume more meat than women. However, this difference increased significantly in countries with greater human development and gender equality. The paradoxical gender gap in meat consumption aligns with previous research that suggests greater differences in behavior across genders in contexts that are more developed and gender equal. We discuss implications for theories of culture and gender as well as practical implications for global meat reduction.

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.

Testosterone, gender identity and gender-stereotyped personality attributes

Sex/gender differences in personality associated with gender stereotyped behavior are widely studied in psychology yet remain a subject of ongoing debate. Exposure to testosterone during developmental periods is considered to be a primary mediator of many sex/gender differences in behavior. Extensions of this research has led to both lay beliefs and initial research about individual differences in basal testosterone in adulthood relating to "masculine" personality. In this study, we explored the relationships between testosterone, gender identity, and gender stereotyped personality attributes in a sample of over 400 university students (65 % female assigned at birth). Participants provided ratings of their self-perceived masculinity and femininity, resulting in a continuous measure of gender identity, and a set of agentic and communal personality attributes. A saliva sample was also provided for assay of basal testosterone. Results showed no compelling evidence that basal testosterone correlates with gender-stereotyped personality attributes or explains the relationship between sex/gender identity and these attributes, across, within, or covarying out sex assigned at birth. Contributing to a more gender diverse approach to assessing sex/gender relationships with personality and testosterone, our continuous measure of self-perceived masculinity and femininity predicted additional variance in personality beyond binary sex and showed some preliminary but weak relationships with testosterone. Results from this study cast doubt on the activational testosterone-masculinity hypothesis for explaining sex differences in gender stereotyped traits and within-sex/gender variation in attributes associated with agency and communality.

An evolutionary analysis of the applicability and utility of the clinico-pathological method in psychiatry

Unlike other medical specialties, psychiatry has not been involved in the theoretical shift that replaced the syndromal approach with the clinico-pathological method, which consists in explaining clinical manifestations by reference to morbid anatomical and physiological changes. Past and present discussions on the applicability of the clinico-pathological method in psychiatry are based on a pre-Darwinian concept of biology as the study of proximate causation. Distinguishing between mediating mechanisms and evolved functions, an evolutionary perspective offers an original contribution to the debate by overcoming the opposite views of dualism (i.e., the clinico-pathological method is not applicable to disorders of the mind) and neuroessentialism (i.e., the definitive way of explaining psychiatric disorders is by reference to the brain and its activity). An evolutionary perspective offers original insights on the utility of the clinico-pathological method to solve critical questions of psychiatric research and clinical practice, including the distinction between mental health and illness, a better understanding of the etiology and pathophysiology, the classification and differential diagnosis of psychiatric disorders, and the development of more efficacious psychiatric treatments.

Prenatal androgen exposure and sex-typical play behaviour: A meta-analysis of classic congenital adrenal hyperplasia studies

Thousands of non-human mammal experiments have demonstrated that early androgen exposure exerts long-lasting effects on neurobehavioural sexual differentiation. In humans, females with classic congenital adrenal hyperplasia (CAH) are exposed to unusually high concentrations of androgens prenatally, whereas prenatal concentrations of androgens in males with CAH are largely normal. The current meta-analysis included 20 independent samples and employed multi-level meta-analytic models. Consistently across all 7 male-typical and female-typical play outcomes, in the expected directions, the present study found significant and large average differences between control males and control females (gs = 0.83-2.78) as well as between females with CAH and control females (gs = 0.95-1.08), but differences between males with CAH and control males were mostly negligible and were non-significant for 6 of the 7 outcomes (gs = 0.04-0.27). These meta-analytic findings suggest that prenatal androgen exposure masculinises and defeminises play behaviour in humans. Broader implications in relation to sex chromosomes, brain development, oestrogens, socio-cognitive influences, other aspects of sex-related behavioural development, and gender nonconformity are discussed.

Effects of Exercise Habits and Gender on Sports e-Learning Behavior: Evidence from an Eye-Tracking Study

Background/Objective

In the post-epidemic era, an increasing number of individuals were accustomed to learning sports and physical activity knowledge online for fitness and health demands. However, most previous studies have examined the influence of e-learning materials and resources on learners and have neglected intrinsic factors such as experience and physiological characteristics. Therefore, we conducted a study to investigate the effect of exercise habits and gender on sports e-learning behavior via eye-tracking technology.

Methods

We recruited a sample of 60 undergraduate students (mean age = 19.6) from a university in Nanjing, China. They were randomly assigned into 4 groups based on 2 genders × 2 exercise habits. Their gaze behavior was collected by an eye-tracking device during the experiment. The cognitive Load Test and Learning Effect Test were conducted at the end of the individual experiment.

Results

(1) Compared to the non-exercise habit group, the exercise habit group had a higher fixation count (P<0.05), a shorter average fixation duration (P<0.05), a smaller average pupil diameter (P<0.05), and a lower subjective cognitive load (P<0.05) and better learning outcome (P<0.05). (2) Male participants showed a greater tendency to process information from the video area of interest (AOIs), and had lower subjective cognitive load (P < 0.05) and better learning outcomes (P < 0.05). (3) There was no interaction effect between exercise habits and gender for any of the indicators (P > 0.05).

Conclusion

Our results indicate that exercise habits effectively enhance sports e-learning outcomes and reduce cognitive load. The exercise habits group showed significant improvements in fixation counts, average fixation duration, and average pupil diameter. Furthermore, male subjects exhibited superior learning outcomes, experienced lower cognitive load, and demonstrated greater attentiveness to dynamic visual information. These conclusions are expected to improve sports e-learning success and address educational inequality.

Are many sex/gender differences really power differences?

This research addresses the long-standing debate about the determinants of sex/gender differences. Evolutionary theorists trace many sex/gender differences back to natural selection and sex-specific adaptations. Sociocultural and biosocial theorists, in contrast, emphasize how societal roles and social power contribute to sex/gender differences beyond any biological distinctions. By connecting two empirical advances over the past two decades-6-fold increases in sex/gender difference meta-analyses and in experiments conducted on the psychological effects of power-the current research offers a novel empirical examination of whether power differences play an explanatory role in sex/gender differences. Our analyses assessed whether experimental manipulations of power and sex/gender differences produce similar psychological and behavioral effects. We first identified 59 findings from published experiments on power. We then conducted a P-curve of the experimental power literature and established that it contained evidential value. We next subsumed these effects of power into 11 broad categories and compared them to 102 similar meta-analytic sex/gender differences. We found that high-power individuals and men generally display higher agency, lower communion, more positive self-evaluations, and similar cognitive processes. Overall, 71% (72/102) of the sex/gender differences were consistent with the effects of experimental power differences, whereas only 8% (8/102) were opposite, representing a 9:1 ratio of consistent-to-inconsistent effects. We also tested for discriminant validity by analyzing whether power corresponds more strongly to sex/gender differences than extraversion: although extraversion correlates with power, it has different relationships with sex/gender differences. These results offer novel evidence that many sex/gender differences may be explained, in part, by power differences.

Navigating Love in a Post-Pandemic World: Understanding Young Adults' Views on Short- and Long-Term Romantic Relationships

The uncertain future due to the COVID-19 pandemic and the technological advancements may have altered young adults' experiences of romantic relationships. It is unclear whether individuals will continue to prefer traditional long-term romantic relationships (LTRR) or opt for short-term ones (STRR). This research describes how young adults in Malaysia perceive LTRR and STRR. Using the structured approach of the theory of social representations, data were collected from 512 participants; 238 (46.48%) male; Mage 21.75; majority were heterosexual and students, and analyzed using prototypical analysis to reveal high consensus elements. Five observations were made: (1) females prioritize "love" in both STRR and LTRR, while males prioritize "love" only in LTRR; (2) females prioritize "marriage" in LTRR, while males prioritize "trust," "comfort," and "stability." Males do not consider "marriage" as part of a LTRR; (3) both males and females view STRR positively, while LTRR are viewed more practically; (4) "sex" is a core element in STRR but is absent in LTRR; (5) males differentiate between STRR and LTRR with no overlapping elements. These findings provide insight into the social representations of romantic relationships among young adults in Malaysia and suggest future directions for research in the field.

Sex and gender correlates of sexually polymorphic cognition

BACKGROUND

Sexually polymorphic cognition (SPC) results from the interaction between biological (birth-assigned sex (BAS), sex hormones) and socio-cultural (gender identity, gender roles, sexual orientation) factors. The literature remains quite mixed regarding the magnitude of the effects of these variables. This project used a battery of classic cognitive tests designed to assess the influence of sex hormones on cognitive performance. At the same time, we aimed to assess the inter-related and respective effects that BAS, sex hormones, and gender-related factors have on SPC.

METHODS

We recruited 222 adults who completed eight cognitive tasks that assessed a variety of cognitive domains during a 150-min session. Subgroups were separated based on gender identity and sexual orientation and recruited as follows: cisgender heterosexual men (n = 46), cisgender non-heterosexual men (n = 36), cisgender heterosexual women (n = 36), cisgender non-heterosexual women (n = 38), gender diverse (n = 66). Saliva samples were collected before, during, and after the test to assess testosterone, estradiol, progesterone, cortisol, and dehydroepiandrosterone. Psychosocial variables were derived from self-report questionnaires.

RESULTS

Cognitive performance reflects sex and gender differences that are partially consistent with the literature. Interestingly, biological factors seem to better explain differences in male-typed cognitive tasks (i.e., spatial), while psychosocial factors seem to better explain differences in female-typed cognitive tasks (i.e., verbal).

CONCLUSION

Our results establish a better comprehension of SPC over and above the effects of BAS as a binary variable. We highlight the importance of treating sex as a biological factor and gender as a socio-cultural factor together since they collectively influence SPC.

Levels of Aggression Escalation in Adult/Geriatric Occupational Therapy Workplaces

Workplace aggression can escalate from verbal to physical, adding risk of physical injury to negative psychological impact. Understanding escalation is necessary to develop effective violence intervention/prevention programs, but its occurrence is not well documented. An online survey determined if and how aggression escalates in occupational therapy (OT) workplaces. Because local culture can influence workplace events we compared surveys from northeastern states with the lowest rates of homicide to southeastern states with the highest. Ninety four OTs working in southeastern or northeastern states reported details of the most recent verbal and/or physical aggressive event initiated by clients (NIOSH Type 2) or staff (NIOSH Type 3) they witnessed or experienced in the workplace within the last year. Aggressor status, motivation, actions; therapist reactions, injuries and psychological sequelae were queried in logical order. Behavior inter-correlation followed by cluster analysis determined if levels of escalation could be detected. Analyses grouped events into five escalation levels in which progressively more hostile or damaging behaviors were added at each successive level. Higher levels involved known risk factors: Younger, reactively angry clients with prior aggression histories escalated attacks to involve restraint, calls for help and physical injury. Southeastern aggressor/target interactions appeared more combative, seemingly regardless of personal risk. Remarkably, northeastern OTs reported significantly more positive and fewer negative feelings across levels of escalation. OT workplace aggression occurs frequently, can escalate to injurious levels and requires prevention/intervention. How therapists maintain positive attitudes in the face of violence deserves further study.

Sex differences in the rapid detection of neutral faces associated with emotional value

BACKGROUND

Rapid detection of faces with emotional meaning is essential for understanding the emotions of others, possibly promoting successful interpersonal relationships. Although few studies have examined sex differences in the ability to detect emotional faces, it remains unclear whether faces with emotional meaning capture the attention of females and males differently, because emotional faces have visual saliency that modulates visual attention. To overcome this issue, we tested the rapid detection of the neutral faces associated with and without learned emotional value, which are all regarded as free from visual saliency. We examined sex differences in the rapid detection of the neutral female and male faces associated with emotional value.

METHODS

First, young adult female and male participants completed an associative learning task in which neutral faces were associated with either monetary rewards, monetary punishments, or no monetary outcomes, such that the neutral faces acquired positive, negative, and no emotional value, respectively. Then, they engaged in a visual search task in which previously learned neutral faces were presented as discrepant faces among newly presented neutral distractor faces. During the visual search task, the participants were required to rapidly identify discrepant faces.

RESULTS

Female and male participants exhibited comparable learning abilities. The visual search results demonstrated that female participants achieved rapid detection of neutral faces associated with emotional value irrespective of the sex of the faces presented, whereas male participants showed this ability only for male faces.

CONCLUSIONS

Our results demonstrated that sex differences in the ability to rapidly detect neutral faces with emotional value were modulated by the sex of those faces. The results suggest greater sensitivity to faces with emotional significance in females, which might enrich interpersonal communication, regardless of sex.

Do Measures of Systemizing and Empathizing Reflect Perceptions of Gender Differences in Learning Affordances?

Gender differences in systemizing and empathizing are sometimes attributed to inherent biological factors. We tested whether such effects are more often interpreted as reflecting men's and women's different learning affordances. Study 1 (N = 624) estimated gender differences in item-level activities from systemizing and empathizing scales (SQ, EQ) in large representative samples. Lay coders (Study 2, N = 199) and psychology experts (Study 3, N = 116) rated SQ and EQ activities as being more learned (vs. innate) and believed that men receive more systemizing and women receive more empathizing (Study 3 only) affordances. Items showing the largest gender differences in Study 1 were those rated as having the largest gender affordances (more than gendered genetic advantages) in Studies 2 and 3. Claims about inherent sex differences in systemizing, and to a lesser degree empathizing, appear to be out of step with a consensus view from the public and psychological scientists.

Childhood Overeating and Disordered Eating From Early Adolescence to Young Adulthood: A Longitudinal Study on the Mediating Role of BMI, Victimization and Desire for Thinness

Eating disorders have early origins, and there could be a continuum between childhood eating behaviors, such as overeating, and long-term disordered eating, but this remains to be shown. BMI, desire for thinness and peer victimization could influence this continuum, but their interactions are unknown. To fill this gap, the study used data from the Quebec Longitudinal Study of Child Development (N = 1511; 52% girls), in which 30.9% of youth presented a trajectory associated with high disordered eating from 12 to 20 years. The results support an indirect association between overeating at age 5 and disordered eating trajectories, with different mediation processes observed between boys and girls. The findings underscore the importance of promoting healthy body images and eating behaviors among youths.

The sex-dependent response to psychosocial stress and ischaemic heart disease

Stress is an important risk factor for modern chronic diseases, with distinct influences in males and females. The sex specificity of the mammalian stress response contributes to the sex-dependent development and impacts of coronary artery disease (CAD). Compared to men, women appear to have greater susceptibility to chronic forms of psychosocial stress, extending beyond an increased incidence of mood disorders to include a 2- to 4-fold higher risk of stress-dependent myocardial infarction in women, and up to 10-fold higher risk of Takotsubo syndrome-a stress-dependent coronary-myocardial disorder most prevalent in post-menopausal women. Sex differences arise at all levels of the stress response: from initial perception of stress to behavioural, cognitive, and affective responses and longer-term disease outcomes. These fundamental differences involve interactions between chromosomal and gonadal determinants, (mal)adaptive epigenetic modulation across the lifespan (particularly in early life), and the extrinsic influences of socio-cultural, economic, and environmental factors. Pre-clinical investigations of biological mechanisms support distinct early life programming and a heightened corticolimbic-noradrenaline-neuroinflammatory reactivity in females vs. males, among implicated determinants of the chronic stress response. Unravelling the intrinsic molecular, cellular and systems biological basis of these differences, and their interactions with external lifestyle/socio-cultural determinants, can guide preventative and therapeutic strategies to better target coronary heart disease in a tailored sex-specific manner.

Linking gender differences with gender equality: A systematic-narrative literature review of basic skills and personality

There is controversy regarding whether gender differences are smaller or larger in societies that promote gender equality highlighting the need for an integrated analysis. This review examines literature correlating, on a national level, gender differences in basic skills-mathematics, science (including attitudes and anxiety), and reading-as well as personality, to gender equality indicators. The aim is to assess the cross-national pattern of these differences when linked to measures of gender equality and explore new explanatory variables that can shed light on this linkage. The review was based on quantitative research relating country-level measures of gender differences to gender equality composite indices and specific indicators. The findings show that the mathematics gender gap from the PISA and TIMMS assessments, is not linked to composite indices and specific indicators, but gender differences are larger in gender-equal countries for reading, mathematics attitudes, and personality (Big Five, HEXACO, Basic Human Values, and Vocational Interests). Research on science and overall scores (mathematics, science, and reading considered together) is inconclusive. It is proposed that the paradox in reading results from the interrelation between basic skills and the attempt to increase girls' mathematics abilities both acting simultaneously while the paradox in mathematics attitudes might be explained by girls being less exposed to mathematics than boys. On the other hand, a more nuanced understanding of the gender equality paradox in personality is advanced, in which a gene-environment-cultural interplay accounts for the phenomenon. Challenges for future cross-national research are discussed.

How the Big Five personality traits related to aggression from perspectives of the benign and malicious envy

BACKGROUND

Prior studies have indicated the link between the Big Five personality traits and aggression. Based on the general aggression model, the purpose of this study is to reveal the formation mechanism of aggression from the people's internal emotional perspective. Envy is a typical negative emotion that can be divided into benign/malicious envy. Therefore, we aim to explore the intrinsic role of benign/malicious envy within the Big Five personality traits in its connection to aggression.

METHODS

We recruited 839 participants [229 men (27.29%) and 610 women (72.71%); mean age ± SD = 19.45 ± 2.39] who we tested with the NEO Personality Inventory, the Benign and Malicious Envy Scale, and the Aggression Questionnaire.

RESULTS

The results of suggested that neuroticism was significantly and positively associated with aggression, while agreeableness was negatively related to aggression. Moreover, mediation analysis revealed that malicious envy works both in the relationship of neuroticism-aggression and agreeableness-aggression.

CONCLUSIONS

The current study advanced knowledge of the general aggression model. Most importantly, it reveals that malicious envy, as a type of envy, plays an important mediating role between neuroticism, agreeableness and aggression. Meanwhile, the cross-gender path analysis supports the stability of the mediating role of malicious envy. This finding provides new insights into the intervention of aggression from the perspective of envy.

Sex and Sexual Orientation Differences in Sexuality and Mate Choice Criteria

Previous research has documented several reliable differences between men and women in terms of mate preferences regarding age, physical appearance, financial prospects, and more. However, most of the research has been on heterosexual populations. The current study attempted to further explore those differences in non-heterosexual populations. The project was part replication regarding heterosexual populations and part exploratory regarding non-heterosexual populations. The sample contained 3298 participants, including 1863 males (1675 gynephiles, 56 androphiles, 132 bisexuals) and 1435 females (1037 androphiles, 33 gynephiles, 365 bisexuals). Participants responded to questions about mate preferences in terms of good financial prospects, good looks, chastity, ambition/industriousness, youth/age, uncommitted sex, visual sexual stimuli, status, physical attractiveness, jealousy, and interest in short- versus long-term mating. Results replicated typical sex differences between heterosexual men and women in all measures we analyzed. We also found several instances when bisexual respondents were more different from heterosexual respondents than homosexual respondents (specifically regarding interest in uncommitted sex, the importance of chastity, and interest in short-term mating). Despite limitations in data collection, the results demonstrate that homosexual and bisexual individuals do not always form a heterogenous group.

Gender differences in aggression: A multiplicative function of outward anger expression

Individuals with a higher (vs. lower) tendency to outwardly express anger (i.e., greater anger-out) generally exhibit greater aggression; men (vs. women) also tend to be more aggressive. Although the general aggression model posits that multiple person variables trigger aggression, the combined effects of multiple person variables are poorly understood. Thus, the aim of this study was to examine the nature of the relation between gender, anger-out, and reactive aggression. In particular, we were interested in whether the effects of anger-out and gender are additive or multiplicative. Specifically, we tested whether men exhibit higher levels of aggression than women at a consistent ratio across all levels of anger-out (i.e., the multiplicative model) or at a fixed amount depending on the level of anger-out (i.e., the additive interaction model). To this end, undergraduate participants (N = 203) completed a task in which they were falsely instructed that their objective was to respond more quickly than a same-sex opponent. They were told that whoever responded more quickly would administer a white noise burst to the opponent and choose its intensity, which served as our measure of aggression. Compared to an additive interaction model, the multiplicative model exhibited a better fit. Specifically, men displayed proportionately more aggression than women with the same level of anger-out. Research on and treatment for aggression should consider the multiplicative effects of factors related to aggression.

Social Construction and Evolutionary Perspectives on Gender Differences in Post-traumatic Distress: The Case of Status Loss Events

Women report greater post-traumatic distress (PTD) than men following physically threatening events. However, gender differences in PTD following social stressors such as status losses are understudied. Whereas the social construction account points to a general sensitivity in women following any type of stressor, the evolutionary account suggests enhanced sensitivity to status losses in men, especially following inter-males aggressions. These propositions were examined in two studies (Study 1, N = 211; Study 2, N = 436). Participants were asked to recall a status loss and to fill out measures assessing PTD and depression severity. In line with the evolutionary account, men, as compared to women, displayed enhanced PTD following status loss. Status losses conducted by men against men were associated with greater PTD than were instances involving other target-aggressor pairings. Finally, age was negatively associated with PTD in men but not in women. The examination of evolutionary challenges modifies the standard view linking the female gender to enhanced sensitivity to trauma. Thus, the pattern of enhanced sensitivity to stressful events appears to be affected by gender- and development-specific adaptive challenges.

Understanding the Magnitude of Psychological Differences Between Women and Men Requires Seeing the Forest and the Trees

Whether women and men are psychologically very similar or quite different is a contentious issue in psychological science. This article clarifies this issue by demonstrating that larger and smaller sex/gender differences can reflect differing ways of organizing the same data. For single psychological constructs, larger differences emerge from averaging multiple indicators that differ by sex/gender to produce scales of a construct’s overall typicality for women versus men. For example, averaging self-ratings on personality traits more typical of women or men yields much larger sex/gender differences on measures of the femininity and masculinity of personality. Sex/gender differences on such broad-gauge, thematic variables are large relative to differences on their component indicators. This increased effect magnitude for aggregated scales reflects gains in both their reliability and validity as indicators of sex/gender. In addition, in psychological domains such as vocational interests that are composed of many variables, at least some of which differ by sex/gender, the multivariate distance between women and men is typically larger than the differences on the component variables. These analyses encourage recognition of the interdependence of sex/gender similarity and difference in psychological data.

Body mass and sex, but not breeding condition and season, influence open‐field exploration in the yellow‐necked mouse

Theory predicts that risk taking should be influenced by external (e.g., season) and internal (e.g., breeding condition, sex, and body mass) conditions. We investigated whether these factors are associated with a potentially risky behavior: exploration of a novel environment. We conducted repeated open‐field tests of exploration in a common forest rodent, the yellow‐necked mouse Apodemus flavicollis. Contrary to expectations, the exploration did not vary with the season (spring vs. fall) or the reproductive status of the tested animals. Also unexpectedly, there was an inverted U‐shaped relationship between body mass and exploration: animals with intermediate body mass tended to have the highest exploration tendencies. Males were more exploratory than females. Finally, even after adjusting for the effects of body mass and sex, individuals exhibited consistent, repeatable differences in exploration tendencies (“behavioral types” or “personalities”). The discrepancies between certain broad generalizations and our results suggest that risk taking depends on details of species‐specific biology.

Sex and gender differences in the development of empathy

The topic of typical sex and gender difference in empathy is examined in both a developmental and neuroscientific perspective. Empathy is construed as a multi-layered phenomenon with various degrees of complexity unfolding in ontogeny. The different components of empathy (i.e., affective, cognitive, and prosocial motivation) will be discussed as they interact and are expressed behaviorally. Significant sex/gender differences in empathy are discussed in relation to putative bottom-up or top-down processes underlying empathetic responses. The early onset and the pervasive presence of such sex/gender differences throughout the lifespan are further discussed in light of social and neurobiological modeling factors, including early socialization, brain's structural/functional variances, as well as genetics and hormonal factors.

Applying an Evolutionary Approach of Risk-Taking Behaviors in Adolescents

Risk-taking behaviors in adolescents have traditionally been analyzed from a psychopathological approach, with an excessive emphasis on their potential costs. From evolutionary theory we propose that risk-taking behaviors can be means through which adolescents obtain potential benefits for survival and reproduction. The present study analyses sex differences in three contexts of risk (i.e., risk propensity, expected benefits and risk perception) in the evolutionary specific domains and the predictive value of these domains over risk-taking behaviors, separately in female and male adolescents. 749 adolescents (females = 370) valued their risk perception, expected benefits and risk propensity through the Evolutionary Domain-Specific Risk Scale, as well as their engagement in risk-taking behaviors through the Risky Behavior Questionnaire. Male adolescents showed lower risk perception in two evolutionary domains, expected higher benefits in two other domains and showed higher risk propensity in six domains. Female adolescents showed lower risk perception in two domains. Additionally, risk perception, expected benefits and risk propensity in the evolutionary domains predicted the engagement in risk-taking behaviors in male adolescents, whereas in female adolescents only expected benefits and risk propensity showed a predictive effect over risk-taking behaviors. These results suggest the potential role of evolutionary mechanisms on risk-taking behaviors in adolescents. Results have practical implications for interventions programs aimed at reducing risk-taking behaviors. In addition to considering sex differences, intervention programs should consider alternative behaviors through which adolescents can reach their evolutionary goals, and handle the risks related to those behaviors that cannot be replaced but have potential benefits for adolescents.

Metric Goodness and Measurement Invariance of the Italian Brief Version of Interpersonal Reactivity Index: A Study With Young Adults

The Interpersonal Reactivity Index (IRI) is a widely used multidimensional measure to assess empathy across four main dimensions: perspective taking (PT) empathic concern (EC) personal distress (PD) fantasy (F). This study aimed to replicate the Italian validation process of the shortened IRI (Interpersonal Reactivity Index) scale in order to confirm its psychometric properties with a sample of young adults. The Gender Measurement Invariance of empathy in this age group was also an objective of the work in order to increase the data on this aspect. A total of 683 Italian university students participated in a non-probabilistic sampling. The 16-item version was confirmed in its four-factor structure but with changes to some items. The model showed good fits with both the CFA and the gender Measurement Invariance. The internal consistency measures were found to be fully satisfactory. Convergent validity was tested by the correlations with the Prosocialness Scale for Adults and The Toronto Alexithymia Scale-20. As hypothesized the measure proved good convergent validity with Prosocialness, i.e., the willingness to assist, help, share, care and empathy with others, and a relevant inverse association with the External Oriented Thinking, characterizing individuals with emotionally poor thinking. This research provided additional evidence for a link between alexithymia and poor empathic abilities in young adults.

The effects of sex and outcome expectancies on perceptions of sexual harassment

Using an outcome expectancy framework, this research sought to understand sex differences in the underlying beliefs that influence harassment perception. One hundred and ninety-six participants (52% women) read a series of vignettes depicting common examples of digital male-on-female sexual harassment. They were asked to what extent they thought each scenario constituted sexual harassment, and how likely the perpetrator would experience positive and negative outcomes. Consistent with predictions, women were more likely to consider the behaviours as harassment than men were. Both sexes harassment perceptions had significant relationships with their outcome expectancies, but we also found evidence of a sex specific moderation; the link between men's negative outcome expectancies was moderated by their positive ones. The results suggest that perceptions of harassment may have sexually asymmetrical underpinnings. Measuring the interplay between positive and negative outcome expectancies in relation to sexual harassment perception is a novel approach, that may have implications for the development of anti-sexual harassment interventions. Implications for theory and future research directions are discussed.

A meta-analysis of sex differences in animal personality: no evidence for the greater male variability hypothesis

The notion that men are more variable than women has become embedded into scientific thinking. For mental traits like personality, greater male variability has been partly attributed to biology, underpinned by claims that there is generally greater variation among males than females in non-human animals due to stronger sexual selection on males. However, evidence for greater male variability is limited to morphological traits, and there is little information regarding sex differences in personality-like behaviours for non-human animals. Here, we meta-analysed sex differences in means and variances for over 2100 effects (204 studies) from 220 species (covering five broad taxonomic groups) across five personality traits: boldness, aggression, activity, sociality and exploration. We also tested if sexual size dimorphism, a proxy for sex-specific sexual selection, explains variation in the magnitude of sex differences in personality. We found no significant differences in personality between the sexes. In addition, sexual size dimorphism did not explain variation in the magnitude of the observed sex differences in the mean or variance in personality for any taxonomic group. In sum, we find no evidence for widespread sex differences in variability in non-human animal personality.

The relation between young adults' trust beliefs in others and interpersonal hostility

The research examined whether, and if so how, young adults' trust beliefs in others were associated with interpersonal hostility. The participants in Study 1 were 139 young adults from the UK (76 women; Mage = 20.8). In Study 2, 88 young adult women from the UK (Mage = 21.5) served as participants. The participants completed a standardized measure of trust beliefs in others (total with reliability, honesty, and emotional subscales). In Study 1, participants imagined they were victims of peer provocation. They were required to judge the intention for the provocation and their retaliation to it. In Study 2, the participants were engaged in a lab-based acquaintanceship interaction that involved the exchange of disclosures. They completed an adjective checklist that assessed anger and evaluated the quality of the conversation. Trust beliefs were linearly and negatively associated with the attribution of hostile intentions, retaliation, anger toward others, and critical evaluation of a developing peer relationship. As expected though, quadratic relations were found. Young adults with very low and those with very high trust beliefs (primarily emotionally based) showed greater attribution of hostile intentions, retaliation, anger toward others, and critical evaluation of a developing peer relationship than did young adults with the middle range of trust beliefs. The linear relations supported the hypothesis that trust promotes psychosocial adjustment. The quadratic relations supported the deviation from the normative trust (centralist) approach primarily for emotional trust beliefs in others.

No Gender Differences in Enrollment for Replicated, Minimally-Different 'Pornographic' Versus 'Photographic' Studies

Objective: Since women tend to use pornography less, they may enroll less in studies concerning it and/or those who do may be gender-atypical. Methods: One study plus replication, assessed proportion of participants reporting being women, responding to each of two, minimally different (one including the word "pornographic") study advertisement versions, and their pornography use frequency, Erotophilia-Erotophobia, and Openness to Experience. Results: Proportion responding to each version did not differ. In one sample only, women responding to one version differed in Openness to Experience. Conclusions: Advertising to North American convenience samples using the word "pornographic", may produce neither self-selection out by, nor over-sampling of gender-atypical, women.

Are Sex Differences in Human Brain Structure Associated With Sex Differences in Behavior?

On average, men and women differ in brain structure and behavior, raising the possibility of a link between sex differences in brain and behavior. But women and men are also subject to different societal and cultural norms. We navigated this challenge by investigating variability of sex-differentiated brain structure within each sex. Using data from the Queensland Twin IMaging study (n = 1,040) and Human Connectome Project (n = 1,113), we obtained data-driven measures of individual differences along a male-female dimension for brain and behavior based on average sex differences in brain structure and behavior, respectively. We found a weak association between these brain and behavioral differences, driven by brain size. These brain and behavioral differences were moderately heritable. Our findings suggest that behavioral sex differences are, to some extent, related to sex differences in brain structure but that this is mainly driven by differences in brain size, and causality should be interpreted cautiously.

Sexual Dimorphism in Language, and the Gender Shift Hypothesis of Homosexuality

Psychological sex differences have been studied scientifically for more than a century, yet linguists still debate about the existence, magnitude, and causes of such differences in language use. Advances in psychology and cognitive neuroscience have shown the importance of sex and sexual orientation for various psychobehavioural traits, but the extent to which such differences manifest in language use is largely unexplored. Using computerised text analysis (Linguistic Inquiry and Word Count: LIWC 2015), this study found substantial psycholinguistic sexual dimorphism in a large corpus of English-language novels (n = 304) by heterosexual authors. The psycholinguistic sex differences largely aligned with known psychological sex differences, such as empathising–systemising, people–things orientation, and men’s more pronounced spatial cognitive styles and abilities. Furthermore, consistent with predictions from cognitive neuroscience, novels (n = 158) by lesbian authors showed minor signs of psycholinguistic masculinisation, while novels (n = 167) by homosexual men had a female-typical psycholinguistic pattern, supporting the gender shift hypothesis of homosexuality. The findings on this large corpus of 66.9 million words indicate how psychological group differences based on sex and sexual orientation manifest in language use in two centuries of literary art.

When Love Just Ends: An Investigation of the Relationship Between Dysfunctional Behaviors, Attachment Styles, Gender, and Education Shortly After a Relationship Dissolution

Much information is known about the long-term consequences of separation and divorce, whereas there is a paucity of studies about the short-term consequences of such experiences. This study investigates the adoption of dysfunctional behaviors (e.g., insistent telephone calls and text messages, verbal threats, and sending unwanted objects) shortly after a relationship dissolution. A total of 136 participants who declared to have been left by their former partner in the previous 6 months were included in this study (i.e., females: n = 84; males: n = 52; mean age = 30.38; SD = 4.19). Attachment styles were evaluated as explanatory variables when facing a relationship dissolution, in connection with a set of (1) demographic variables (i.e., gender, education, and current marital/relationship status), (2) dysfunctional behaviors, and (3) motivations on the basis of those behaviors. Results showed that a secure or dismissing attachment style, a higher education, and currently married (but awaiting separation) status were the protective factors in adopting such dysfunctional behaviors, while the preoccupied and fearful-avoidant subjects, especially females, tended to adopt dysfunctional behaviors (i.e., communication attempts and defamation) and reported fear of abandonment and need for attention as underlying motivations. Future study on longitudinal aspects of the relationship dissolution processes is required to have deeper insights into this phenomenon. This study sheds light on the relationship between adult attachment styles and the motivations behind the adoption of dysfunctional behaviors after a relationship dissolution.

Challenging the binary: Gender/sex and the bio-logics of normalcy

BACKGROUND

We are witnessing renewed debates regarding definitions and boundaries of human gender/sex, where lines of genetics, gonadal hormones, and secondary sex characteristics are drawn to defend strict binary categorizations, with attendant implications for the acceptability and limits of gender identity and diversity.

AIMS

Many argue for the need to recognize the entanglement of gender/sex in humans and the myriad ways that gender experience becomes biology; translating this theory into practice in human biology research is essential. Biological anthropology is well poised to contribute to these societal conversations and debates. To do this effectively, a reconsideration of our own conceptions of gender/sex, gender identity, and sexuality is necessary.

METHODS

In this article, we discuss biological variation associated with gender/sex and propose ways forward to ensure we are engaging with gender/sex diversity. We base our analysis in the concept of "biological normalcy," which allows consideration of the relationships between statistical distributions and normative views. We address the problematic reliance on binary categories, the utilization of group means to represent typical biologies, and document ways in which binary norms reinforce stigma and inequality regarding gender/sex, gender identity, and sexuality.

DISCUSSION AND CONCLUSIONS

We conclude with guidelines and methodological suggestions for how to engage gender/sex and gender identity in research. Our goal is to contribute a framework that all human biologists can use, not just those who work with gender or sexually diverse populations. We hope that in bringing this perspective to bear in human biology, that novel ideas and applications will emerge from within our own discipline.

Gender Matters: Nonlinear Relationships Between Heart Rate Variability and Depression and Positive Affect

Vagally mediated heart rate variability (vmHRV), a measure of the parasympathetic nervous system's control over the heart, is often negatively related to maladaptive emotional outcomes. Recent work suggests that quadratic relationships involving these factors may be present; however, research has not investigated gender differences in these nonlinear functions. To address this gap, the current study tested for quadratic relationships between resting vmHRV and depression and positive affect while investigating gender differences in these relationships. Significant quadratic effects were found between resting vmHRV and reports of both depression symptoms and positive affect in women but not men. Specifically, the lowest levels of depression and the highest levels of positive affect were found at moderate vmHRV in women. These results suggest that examinations of vmHRV's nonlinear associations require the consideration of gender. Our findings are interpreted based on proposed differential neuropsychological mechanisms of vmHRV in men versus women.

Girls exhibit greater empathy than boys following a minor accident

Hundreds of studies find that girls and women report feeling greater empathy than boys and men in response to adverse events befalling others. Despite this, few non-self-report measures demonstrate similar sex differences. This produces the oft-cited conclusion that to conform to societal expectations of appropriate sex-typed behavior females report higher levels of empathy. Several studies of sex differences in areas of brain activation and on infants' and young children's behavior however provide suggestive findings that self-reports reflect actual underlying sex differences in experiencing concern about others. We demonstrate using behavioral indices that females experience more empathy than males after witnessing an adverse event befall a same-sex classmate. In our study, one member of a pair experienced a minor accident on the way to constructing a tower while a bystander observed. We measured whether bystanders ceased their ongoing activity, looked at the victim, waited for the victim to recover from the accident, and actively intervened to help the victim. Female more than male bystanders engaged in these activities. These behavioral results suggest that an adverse event produces different subjective experiences in females than males that motivate objectively different behaviors, consistent with findings from self-report measures of empathy.

Family Experiences and Parent Personality as Antecedents of Pubertal Timing in Girls and Boys

Pubertal timing may be influenced by typical variations in early family environmental events, but questions remain concerning the roles of specific parenting factors, developmental age of exposure to events, moderation by child temperament, and comparability of effects for girls and boys. This study focused on these questions utilizing longitudinal data from 733 same-sex twins (45% girls) in the U.S.; family context was measured at ages 1-3, 4-5, and 6-7 years and pubertal status was assessed annually via self-report at ages 9-15, enabling estimates of pubertal timing. Home environment at ages 4-5 years predicted pubertal timing better than home environment at other ages for both girls and boys, but parent personality was more predictive than home experiences (e.g., divorce, parental harshness, family conflict). Thus, effects of family environment must be considered within the context of parent characteristics, encouraging caution in implicating early environmental experiences as direct influences on early pubertal timing.

COVID-19 Pandemic on Fire: Evolved Propensities for Nocturnal Activities as a Liability Against Epidemiological Control

Humans have been using fire for hundreds of millennia, creating an ancestral expansion toward the nocturnal niche. The new adaptive challenges faced at night were recurrent enough to amplify existing psychological variation in our species. Night-time is dangerous and mysterious, so it selects for individuals with higher tendencies for paranoia, risk-taking, and sociability (because of security in numbers). During night-time, individuals are generally tired and show decreased self-control and increased impulsive behaviors. The lower visibility during night-time favors the partial concealment of identity and opens more opportunities for disinhibition of self-interested behaviors. Indeed, individuals with an evening-oriented chronotype are more paranoid, risk-taking, extraverted, impulsive, promiscuous, and have higher antisocial personality traits. However, under some circumstances, such as respiratory pandemics, the psychobehavioral traits favored by the nocturnal niche might be counter-productive, increasing contagion rates of a disease that can evade the behavioral immune system because its disease cues are often nonexistent or mild. The eveningness epidemiological liability hypothesis presented here suggests that during the COVID-19 pandemic, the evening-oriented psychobehavioral profile can have collectively harmful consequences: there is a clash of core tendencies between the nocturnal chronotype and the recent viral transmission-mitigating safety guidelines and rules. The pandemic safety protocols disrupt much normal social activity, particularly at night when making new social contacts is desired. The SARS-CoV-2 virus is contagious even in presymptomatic and asymptomatic individuals, which enables it to mostly evade our evolved contagious disease avoidance mechanisms. A growing body of research has indirectly shown that individual traits interfering with social distancing and anti-contagion measures are related to those of the nocturnal chronotype. Indeed, some of the social contexts that have been identified as superspreading events occur at night, such as in restaurants, bars, and nightclubs. Furthermore, nocturnal environmental conditions favor the survival of the SARS-CoV-2 virus much longer than daytime conditions. We compare the eveningness epidemiological liability hypothesis with other factors related to non-compliance with pandemic safety protocols, namely sex, age, and life history. Although there is not yet a direct link between the nocturnal chronotype and non-compliance with pandemic safety protocols, security measures and future empirical research should take this crucial evolutionary mismatch and adaptive metaproblem into account, and focus on how to avoid nocturnal individuals becoming superspreaders, offering secure alternatives for nocturnal social activities.

Pandemic Leadership: Sex Differences and Their Evolutionary-Developmental Origins

The COVID-19 pandemic has caused a global societal, economic, and social upheaval unseen in living memory. There have been substantial cross-national differences in the kinds of policies implemented by political decision-makers to prevent the spread of the virus, to test the population, and to manage infected patients. Among other factors, these policies vary with politicians' sex: early findings indicate that, on average, female leaders seem more focused on minimizing direct human suffering caused by the SARS-CoV-2 virus, while male leaders implement riskier short-term decisions, possibly aiming to minimize economic disruptions. These sex differences are consistent with broader findings in psychology, reflecting women's stronger empathy, higher pathogen disgust, health concern, care-taking orientation, and dislike for the suffering of other people-as well as men's higher risk-taking, Machiavellianism, psychopathy, narcissism, and focus on financial indicators of success and status. This review article contextualizes sex differences in pandemic leadership in an evolutionary framework. Evolution by natural selection is the only known process in nature that organizes organisms into higher degrees of functional order, or counteracts the unavoidable disorder that would otherwise ensue, and is therefore essential for explaining the origins of human sex differences. Differential sexual selection and parental investment between males and females, together with the sexual differentiation of the mammalian brain, drive sex differences in cognition and behavioral dispositions, underlying men's and women's leadership styles and decision-making during a global pandemic. According to the sexually dimorphic leadership specialization hypothesis, general psychobehavioral sex differences have been exapted during human evolution to create sexually dimorphic leadership styles. They may be facultatively co-opted by societies and/or followers when facing different kinds of ecological and/or sociopolitical threats, such as disease outbreaks or intergroup aggression. Early evidence indicates that against the invisible viral foe that can bring nations to their knees, the strategic circumspection of empathic feminine health "worriers" may bring more effective and humanitarian outcomes than the devil-may-care incaution of masculine risk-taking "warriors".

Frequency of Recent Binge Drinking Is Associated With Sex-Specific Cognitive Deficits: Evidence for Condition-Dependent Trait Expression in Humans

Evolutionary theory suggests that commonly found sex differences are largest in healthy populations and smaller in populations that have been exposed to stressors. We tested this idea in the context of men’s typical advantage (vs. women) in visuospatial abilities (e.g., mental rotation) and women’s typical advantage (vs. men) in social-cognitive (e.g., facial-expression decoding) abilities, as related to frequent binge drinking. Four hundred nineteen undergraduates classified as frequent or infrequent binge drinkers were assessed in these domains. Trial-level multilevel models were used to test a priori Sex × Group (binge drinking) interactions for visuospatial and social-cognitive tasks. Among infrequent binge drinkers, men’s typical advantage in visuospatial abilities and women’s typical advantage in social-cognitive abilities was confirmed. Among frequent binge drinkers, men’s advantage was reduced for one visuospatial task (Δ d = 0.29) and eliminated for another (Δ d = 0.75), and women’s advantage on the social-cognitive task was eliminated (Δ d = 0.12). Males who frequently engaged in extreme binges had exaggerated deficits on one of the visuospatial tasks, as did their female counterparts on the social-cognitive task. The results suggest sex-specific vulnerabilities associated with recent, frequent binge drinking, and support an evolutionary approach to the study of these vulnerabilities.

Reactions to male-favouring versus female-favouring sex differences: A pre-registered experiment and Southeast Asian replication

Two studies investigated (1) how people react to research describing a sex difference, depending on whether that difference favours males or females, and (2) how accurately people can predict how the average man and woman will react. In Study 1, Western participants (N = 492) viewed a fictional popular-science article describing either a male-favouring or a female-favouring sex difference (i.e., men/women draw better; women/men lie more). Both sexes reacted less positively to the male-favouring differences, judging the findings to be less important, less credible, and more offensive, harmful, and upsetting. Participants predicted that the average man and woman would react more positively to sex differences favouring their own sex. This was true of the average woman, although the level of own-sex favouritism was lower than participants predicted. It was not true, however, of the average man, who - like the average woman - reacted more positively to the female-favouring differences. Study 2 replicated these findings in a Southeast Asian sample (N = 336). Our results are consistent with the idea that both sexes are more protective of women than men, but that both exaggerate the level of same-sex favouritism within each sex - a misconception that could potentially harm relations between the sexes.

Women's socioeconomic position in ontogeny is associated with improved immune function and lower stress, but not with height

Immune function, height and resource accumulation comprise important life history traits in humans. Resource availability models arising from life history theory suggest that socioeconomic conditions influence immune function, growth and health status. In this study, we tested whether there are associations between family income during ontogeny, adult height, cortisol level and immune response in women. A hepatitis B vaccine was administered to 66 young Latvian women from different socioeconomic backgrounds, and blood samples were then collected to measure the level of antibodies that the women produced in response to the vaccination. Cortisol levels were measured from plasma samples pre- and post-vaccination. Women from wealthier families had lower cortisol levels, and women from the highest family income group had the highest levels of antibody titers against hepatitis B vaccine. No significant relationships were observed between cortisol level and immune function, nor between family income and height. The results show that income level during ontogeny is associated with the strength of immune response and with psychoneuroendocrine pathways underlying stress perception in early adulthood. The findings indicate that the quality of the developmental niche is associated with the condition-dependent expression of immune function and stress response.

Global sex differences in personality: Replication with an open online dataset

OBJECTIVE

Sex differences in personality are a matter of continuing debate. In a study on the United States standardization sample of Cattell's 16PF (fifth edition), Del Giudice and colleagues (2012; PLoS ONE, 7, e29265) estimated global sex differences in personality with multigroup covariance and mean structure analysis. The study found a surprisingly large multivariate effect, D = 2.71. Here we replicated the original analysis with an open online dataset employing an equivalent version of the 16PF.

METHOD

We closely replicated the original MG-MCSA analysis on N = 21,567 U.S. participants (63% females, age 16-90); for robustness, we also analyzed N = 31,637 participants across English-speaking countries (61% females, age 16-90).

RESULTS

The size of global sex differences was D = 2.06 in the United States and D = 2.10 across English-speaking countries. Parcel-allocation variability analysis showed that results were robust to changes in parceling (U.S.: median D = 2.09, IQR [1.89, 2.37]; English-speaking countries: median D = 2.17, IQR [1.98, 2.47]).

CONCLUSIONS

Our results corroborate the original study (with a comparable if somewhat smaller effect size) and provide new information on the impact of parcel allocation. We discuss the implications of these and similar findings for the psychology of sex differences.

Gender Differences in Familiar Face Recognition and the Influence of Sociocultural Gender Inequality

Are gender differences in face recognition influenced by familiarity and socio-cultural factors? Previous studies have reported gender differences in processing unfamiliar faces, consistently finding a female advantage and a female own-gender bias. However, researchers have recently highlighted that unfamiliar faces are processed less efficiently than familiar faces, which have more robust, invariant representations. To-date, no study has examined whether gender differences exist for familiar face recognition. The current study addressed this by using a famous faces task in a large, web-based sample of  > 2000 participants across different countries. We also sought to examine if differences varied by socio-cultural gender equality within countries. When examining raw accuracy as well when controlling for fame, the results demonstrated that there were no participant gender differences in overall famous face accuracy, in contrast to studies of unfamiliar faces. There was also a consistent own-gender bias in male but not female participants. In countries with low gender equality, including the USA, females showed significantly better recognition of famous female faces compared to male participants, whereas this difference was abolished in high gender equality countries. Together, this suggests that gender differences in recognizing unfamiliar faces can be attenuated when there is enough face learning and that sociocultural gender equality can drive gender differences in familiar face recognition.

Genetic Influences on Social Relationships: Sex Differences in the Mediating Role of Personality and Social Cognition

Objectives

In humans (and primates more generally), evolutionary fitness arises by two separate routes: conventional reproduction build around dyadic relationships and, reflecting the processes of group augmentation selection, how well individuals are embedded in their community. These processes are facilitated by a suite of genetically inherited neuroendocrines and neurotransmitters. It is not, however, known whether these effects are directly due to genetic factors or are mediated by aspects of personality, or whether there are sex differences in the way this is organised.

Methods

We examine whether dispositional factors related to the processing of social information, such as personality (Big 5 and Impulsivity), attachment style (Anxious and Avoidant dimensions) and sociocognitive capacity (emotion recognition) mediate associations between variation in receptor genes for oxytocin, vasopressin, beta-endorphin, dopamine, serotonin, testosterone and two core social relationship indices (the Sociosexual Orientation Index [SOI] and Support Network size).

Results

In men, variation in dopamine genes indirectly influences SOI through its effect on Impulsivity. In contrast, in women, variation in endorphin and vasopressin genes independently affect Openness to Experience, which mediates indirect effects of these genes on SOI. Moreover, endorphin gene variation also impacts on Network Size in women (but not men), via Extraversion.

Conclusions

These findings reveal that dispositional aspects of personality mediate some genetic effects on behaviour, thereby extending our understanding of how genetic and dispositional variation interact to determine individual differences in human sexual and social cognition and behaviour. The differences between the sexes seem to reflect differences in the two sexes’ social strategies.

Antidepressant-like effects of the Guanxin Danshen formula via mediation of the CaMK II-CREB-BDNF signalling pathway in chronic unpredictable mild stress-induced depressive rats

Background

Depression is a chronic and recurrent syndrome of mood disorder causing immense social and economic burden; thus, treatment should be improved. Guanxin Danshen formula (GXDSF), a natural botanical drug composition prescription, has significant cardiovascular protective effects and is widely used in the clinical treatment of myocardial ischaemic diseases. However, it is still unclear and seldom studied whether GXDSF has neuroprotective effects against depressive disorders. This study explored whether GXDSF has antidepressant-like effects in rats exposed to chronic unpredictable mild stress (CUMS) and analysed the possible underlying neurotrophic expression and psychotropic mechanisms.

Methods

The present study was designed to investigate the antidepressant effects of GXDSF treatment in a CUMS-induced rat model. Based on the clinical doses, the drug-treated group was intragastrically administered GXDSF for 30 days, and rats were simultaneously exposed to CUMS stimulation for 30 days. After induction and drug administration, the depression-like behaviours were determined via the sucrose preference test (SPT), the open field test (OFT), the tail suspension test (TST), and the forced swim test (FST). ELISA kits were used to examine the monoaminergic neurotransmitters, monoamine oxidase (MAO) and Ca²⁺ levels in the hippocampus. Moreover, we measured and analysed the brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) levels and the upstream regulation and signal pathways of BDNF and NGF to explore their related mechanisms in this animal model of depression, including calcium-calmodulin dependent protein kinase-II (CaMKII) and cAMP response element-binding (CREB).

Results

The results revealed that GXDSF may possess significant antidepressant-like effects via improving body weight, raising the sucrose preference in the SPT, increasing the total distance, the number of upright stands, and the residence time of the central zone in the open field test (OPF) and reducing the immobility time in the TST and FST. In addition, GXDSF significantly upregulated the relative levels of neurotransmitters, including dopamine (DA), norepinephrine (NE), and serotonin (5-HT), in a dose-dependent manner and inhibited MAO activities in the hippocampus. Moreover, GXDSF reversed the decline in intracellular CREB and p-CREB expression induced by CUMS, downregulated the phosphorylation levels of intracellular CaMKII and its two subunits CaMKIIα and CaMKIIβ in the hippocampus, and thus, clearly upregulated the downstream effector protein expression levels of BDNF, NGF, and synitaxine-1 in the hippocampus. These data suggest that the antidepressant effects of GXDSF have a potential relationship with regulating changes in the CaMKII-CREB-BDNF pathway.

Conclusions

Despite several limitations of this study, the results have suggested that GXDSF administration possesses antidepressant-like effects in CUMS-treated rats and provide the first in vivo demonstration of a possible mechanism of GXDSF via regulating changes in the CaMKII-CREB-BDNF signalling pathway. These findings provide a novel potential substrate by which herbal antidepressants may exert therapeutic effects in the treatment of depression.

An Exploration of Attitudes Toward Dogs among College Students in Bangalore, India

Simple Summary

The presence of dogs in urban spaces and family homes is becoming increasingly common worldwide. Despite this, investigations into cultural variations in this practice are still new. Using self-report, pen-and-paper surveys, we explored attitudes toward both pet dogs and stray dogs in an urban, college sample in Bangalore, India. We found a notable presence of pet dogs in homes or desire to have a pet dog, as well as the use of affiliative terms (family, companion) regarding these pets. Not surprisingly, we also found expected sex differences between men’s and women’s attitudes toward pet dogs and stray dogs in shared, urban spaces.

Abstract

Conversations in the field of anthrozoology include treatment and distinction of food animals, animals as workers versus pests, and most recently, emerging pet trends including the practice of pet parenting. This paper explores attitudes toward pet dogs in the shared social space of urban India. The data include 375 pen-and-paper surveys from students at CHRIST (Deemed to be University) in Bangalore, India. Reflecting upon Serpell’s biaxial concept of dogs as a relationship of affect and utility, the paper considers the growing trend of pet dog keeping in urban spaces and the increased use of affiliative words to describe these relationships. The paper also explores potential sex differences in attitudes towards pet and stray dogs. Ultimately, these findings suggest that the presence of and affiliation with pet dogs, with reduced utility and increased affect, is symptomatic of cultural changes typical of societies encountering the second demographic transition. Despite this, sex differences as expected based upon evolutionary principles, remain present, with women more likely to emphasize health and welfare and men more likely to emphasize bravery and risk taking.