Assessing interdependence between the self and specific others has a rich history in psychological science. Here, we report a novel scale that measures Shared Fate. Studies 1 and 2 (N 1 = 198, N 2 = 216) show that the Shared Fate Scale has two factors assessing perceived shared fate and emotional shared fate with a target, has good reliability (Cronbach's a = .81 to .91; McDonald's v = .89 to .96), and predicts participants' willingness to help interdependent others. Studies 3 and 4 (N 3 = 695, N 4 = 629) indicate that the Shared Fate Scale has good discriminant, convergent, concurrent, and predictive validity as well as test-retest reliability across a 14-day period. Taken together, our results suggest that the Shared Fate Scale is a useful instrument for work on cooperation, interdependence, and social behavior. However, there are still many open questions about the cognitive architecture underlying perceptions of shared fate and how shared fate interacts with genetic relatedness and other sources of fitness interdependence.

Background. Separate lines of research have shown that menstrual cycling and contextual factors such as the gender of research personnel influence experimental pain reporting. Objectives. This study examines how brief, procedural interactions with female and male experimenters can affect experimentally reported pain (cold pressor task, CPT) across the menstrual cycle. Methods. Based on the menstrual calendars 94 naturally cycling women and 38 women using hormonal contraceptives (M age = 19.83,  SD = 3.09) were assigned to low and high fertility groups. This assignment was based on estimates of their probability of conception given their current cycle day. Experimenters (12 males, 7 females) engaged in minimal procedural interactions with participants before the CPT was performed in solitude. Results. Naturally cycling women in the high fertility group showed significantly higher pain tolerance (81 sec, d = .79) following interactions with a male but not a female experimenter. Differences were not found for women in the low fertility or contraceptive groups. Discussion. The findings illustrate that menstrual functioning moderates the effect that experimenter gender has on pain reporting in women. Conclusion. These findings have implications for standardizing pain measurement protocols and understanding how basic biopsychosocial mechanisms (e.g., person-perception systems) can modulate pain experiences.

We investigate whether age profiles of ethnobiological knowledge developmentare consistent with predictions derived from life history theory about the timing ofproductivity and reproduction. Life history models predict complementary knowledgeprofiles developing across the lifespan for women and men as they experiencechanges in embodied capital and the needs of dependent offspring. We evaluatethese predictions using an ethnobiological knowledge assessment tool developedfor an off-grid pastoralist population known as Choyeros, from Baja California Sur,Mexico. Our results indicate that while individuals acquire knowledge of most dangerousitems and edible resources by early adulthood, knowledge of plants and animalsrelevant to the age and sex divided labor domains and ecologies (e.g., women’shouse gardens, men’s herding activities in the wilderness) continues to develop intomiddle adulthood but to different degrees and at different rates for men and women.As the demands of offspring on parents accumulate with age, reproductive-agedadults continue to develop their knowledge to meet their children’s needs. After controllingfor vision, our analysis indicates that many post-reproductive adults showthe greatest ethnobiological knowledge. These findings extend our understanding ofthe evolved human life history by illustrating how changes in embodied capital andthe needs of dependent offspring predict the development of men’s and women’sethnobiological knowledge across the lifespan.

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Friendships provide social support and mental health benefits, yet the COVID-19 pandemic has limited interactions with friends. In August 2020, we asked participants ( N = 634) about their friendships during the pandemic as part of a larger study. We found that younger people and people with higher subjective SES reported more negative effects on their friendships, including feeling more isolated and lonelier. We also found that stress, isolation, and guilt were associated with greater COVID-related social risk-taking, such as making and visiting new friends in person. Our results suggest the pandemic is affecting friendships differently across demographic groups and these negative effects might motivate social risk-taking.