Despite a staggering body of research demonstrating sex differences in expressed emotion, very few theoretical models (evolutionary or non-evolutionary) offer a critical examination of the adaptive nature of such differences. From the perspective of a socio-relational framework, emotive behaviors evolved to promote the attraction and aversion of different types of relationships by advertising the two most parsimonious properties of reciprocity potential, or perceived attractiveness as a prospective social partner. These are the individual's (a) perceived capacity or ability to provide expedient resources, or to inflict immediate harm onto others, and their (b) perceived trustworthiness or probability of actually reciprocating altruism (Vigil 2007). Depending on the unique social demands and relational constraints that each sex evolved, individuals should be sensitive to advertise "capacity" and "trustworthiness" cues through selective displays of dominant versus submissive and masculine versus feminine emotive behaviors, respectively. In this article, I introduce the basic theoretical assumptions and hypotheses of the framework, and show how the models provide a solid scaffold with which to begin to interpret common sex differences in the emotional development literature. I conclude by describing how the framework can be used to predict condition-based and situation-based variation in affect and other forms of expressive behaviors.

Several hypotheses on the form and function of sex differences in social behaviors were tested. The results suggest that friendship preferences in both sexes can be understood in terms of perceived reciprocity potential-capacity and willingness to engage in a mutually beneficial relationship. Divergent social styles may in turn reflect trade-offs between behaviors selected to maintain large, functional coalitions in men and intimate, secure relationships in women. The findings are interpreted from a broad socio-relational framework of the types of behaviors that facilitate selective advertisement and investment of reciprocity potential across individuals and within groups of men and women.

This article provides a review of evolutionary theory and empirical research on mate choices in non-mechanisms that operate within species and are principle factors in the evolution of sex differences (Darwin, 1871). These mechanisms are called sexual selection and involve competition with members of the same sex over mates (intrasexual competition) and discriminative choice of mating partners (intersexual choice). The most common mating dynamic involves male-male competition over access to mates and female choice of mating partners (Andersson, 1994). In the first section, we describe why this dynamic is so common and when exceptions (e.g., male choice) are predicted to evolve. In the second section, we describe intersexual choice in nonhuman species.

BackgroundCurrent levels and dangers of opioid use in the U.S. warrant the investigation of harm-reducing treatment alternatives.PurposeA preliminary, historical, cohort study was used to examine the association between enrollment in the New Mexico Medical Cannabis Program (MCP) and opioid prescription use.MethodsThirty-seven habitual opioid using, chronic pain patients (mean age = 54 years; 54% male; 86% chronic back pain) enrolled in the MCP between 4/1/2010 and 10/3/2015 were compared to 29 non-enrolled patients (mean age = 60 years; 69% male; 100% chronic back pain). We used Prescription Monitoring Program opioid records over a 21 month period (first three months prior to enrollment for the MCP patients) to measure cessation (defined as the absence of opioid prescriptions activity during the last three months of observation) and reduction (calculated in average daily intravenous [IV] morphine dosages). MCP patient-reported benefits and side effects of using cannabis one year after enrollment were also collected.ResultsBy the end of the 21 month observation period, MCP enrollment was associated with 17.27 higher age- and gender-adjusted odds of ceasing opioid prescriptions (CI 1.89 to 157.36, p = 0.012), 5.12 higher odds of reducing daily prescription opioid dosages (CI 1.56 to 16.88, p = 0.007), and a 47 percentage point reduction in daily opioid dosages relative to a mean change of positive 10.4 percentage points in the comparison group (CI -90.68 to -3.59, p = 0.034). The monthly trend in opioid prescriptions over time was negative among MCP patients (-0.64mg IV morphine, CI -1.10 to -0.18, p = 0.008), but not statistically different from zero in the comparison group (0.18mg IV morphine, CI -0.02 to 0.39, p = 0.081). Survey responses indicated improvements in pain reduction, quality of life, social life, activity levels, and concentration, and few side effects from using cannabis one year after enrollment in the MCP (ps<0.001).ConclusionsThe clinically and statistically significant evidence of an association between MCP enrollment and opioid prescription cessation and reductions and improved quality of life warrants further investigations on cannabis as a potential alternative to prescription opioids for treating chronic pain.

Conservative, Republican sympathizers show heightened threat reactivity, but greater felt happiness than liberal, Democrat sympathizers. Recent evolutionary models interpret these findings in the context of broader perceptual and expressive proclivities for advertising cues of competency (Republicans) and trustworthiness (Democrats) to others, and in ways that facilitate the formation of distinct social networks, in coordination with individuals’ life histories. Consistent with this perspective, I found that Republican sympathizers were more likely to report larger social networks and interpret ambiguous facial stimuli as expressing more threatening emotions as compared to Democrat sympathizers, who also reported greater emotional distress, relationship dissatisfaction, and experiential hardships. The findings are discussed in the context of proximate and ultimate explanations of social cognition, relationship formation, and societal cohesion.

Life history theory provided a framework for examining the relations among child sexual abuse (CSA), childhood adversity, and patterns of reproductive development and behavior. A community survey that assessed CSA, life history variables (e.g., age of menarche), and social and family background was administered to 623 women (mean age=26.9 years). Independent of social and family background, CSA was associated with earlier age of (a) menarche, (b) first sexual relationship, (c) desire to have children, (d) first childbirth, and (e) lower self-evaluated physical attractiveness. Cluster analyses revealed different patterns of experiential correlates of reproductive development within the group of abused women, suggesting CSA may operate in combination with other childhood circumstances to modify the timing and pattern of individual maturation.

The study examines group and individual differences in psychological functioning and hypothalamic-pituitary-adrenal and sympathetic nervous system (SNS) activity among adolescents displaced by Hurricane Katrina and living in a U.S. government relocation camp (n = 62, ages 12-19 years) 2 months postdisaster. Levels of salivary cortisol, salivary alpha-amylase, depression, anxiety, distress, aggression, and self-esteem for this group were contrasted with a demographically matched no-trauma control group (n = 53). Results revealed that hurricane exposure and SNS activity moderated the relations between lower cortisol and higher internalizing behaviors. Sex-related differences were observed in behavioral adjustment and stress regulation. Implications of sex differences in biobehavioral adjustment to loss, displacement, and relocation are discussed in relation to evolutionary and developmental theory.

This experiment examines the impact of biological sex and audience composition on laboratory-induced ischemic pain intensity and observational coding of other people's pain behaviors. Situational context was manipulated by varying the sex and number of audience stimuli in the laboratory setting during the pain task and during observational evaluations of other people's pain suffering. The analyses revealed sex differences in felt pain intensity and observable pain behaviors, with male subjects reporting lower pain intensity and evidencing fewer pain behaviors than female subjects on average. Follow-up analyses revealed that, after controlling for social anxiety, audience composition was linked to felt pain intensity, and this relation was moderated by participant sex and audience sex, such that only male subjects showed decreased pain intensity with increasing number of female audience members. Sex differences were also found in the rating of other people's pain behaviors, with male observers rating the pain of others lower than female observers. Composition of the audience influenced observers' pain ratings such that the presence of more male subjects in the audience correlated with lower observer ratings, whereas the presence of more female subjects correlated with higher observer ratings. This is the first study to show that the sex and the composition of the social context in which pain is experienced affects the intensity of felt pain and the evaluation of other people's pain suffering. Implications of the findings for measuring and interpreting pain suffering in male and female patients by male and female treatment providers in health care settings are discussed.