Although cooperative social networks are considered key to human evolution, emphasis has usually been placed on the functions of men’s cooperative networks. What do women’s networks look like? Do they differ from men’s networks and what does this suggest about evolutionarily inherited gender differences in reproductive and social strategies? In this paper, we test the ‘universal gender differences’ hypothesis positing gender-specific network structures against the ‘gender reversal’ hypothesis that posits that women’s networks look more ‘masculine’ under matriliny. Specifically, we ask whether men’s friendship networks are always larger than women’s networks and we investigate measures of centrality by gender and descent system. To do so, we use tools from social network analysis and data on men’s and women’s friendship ties in matrilineal and patrilineal Mosuo communities. In tentative support of the gender reversal hypothesis, we find that women’s friendship networks in matriliny are relatively large. Measures of centrality and generalized linear models otherwise reveal greater differences between communities than between men and women. The data and analyses we present are primarily descriptive given limitations of sample size and sampling strategy. Nonetheless, our results provide support for the flexible application of social relationships across genders and clearly challenge the predominant narrative of universal gender differences across space and time.

Although cooperative social networks are considered key to human evolution, emphasis has usually been placed on the functions of men’s cooperative networks. What do women's networks look like? Do they resemble or differ from men's and what does this suggest about evolutionarily inherited gender differences in reproductive and social strategies? In this paper, we test the ‘universal gender differences’ hypothesis positing gender-specific network structures against the ‘gender reversal’ hypothesis that posits women's networks looking more 'masculine' under matriliny. Specifically, we ask whether men's friendship networks are always larger than women's and we investigate measures of centrality by gender and descent system. To do so, we use tools from social network analysis and data on men’s and women’s friendship ties in matrilineal and patrilineal Mosuo communities. In tentative support of the gender reversal hypothesis, we find that women's friendship networks in matriliny are relatively large. Measures of centrality and generalized linear models otherwise reveal greater differences between communities than between men and women. The data and analyses we present are primarily descriptive given limitations of sample size and sampling strategy. Nonetheless, our results provide support for the flexible application of social relationships across genders and clearly challenge the predominant narrative of universal gender differences across space and time.

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Increased access to defensible material wealth is hypothesized to escalate inequality. Market integration, which creates novel opportunities in cash economies provides a means of testing this hypothesis. Using demographic data collected from 505 households among the matrilineal and patrilineal Mosuo in 2017, we test whether MI is associated with increased material wealth, whether increased material wealth is associated with wealth inequality, and whether being in a matrilineal versus patrilineal kinship system alters the relationship between wealth and inequality. We find evidence that market integration, measured as distance to the nearest source of tourism and primary source of household income, was associated with increased household income and “modern” asset value. Both village-level market integration and mean asset value were associated negatively, rather than positively, with inequality, contrary to predictions. Finally, income, modern wealth, and inequality were higher in matrilineal communities, which are located closer to the center of tourism and where tourism has long provided a relatively stable source of income. However, we also observed exacerbated inequality with increasing farm animal value in patriliny. We conclude that the forces affecting wealth and inequality depend on local context and that the importance of local institutions is obscured by aggregate statistics drawn from modern nation states.

Background: Human populations native to high altitude exhibit numerous genetic adaptations to hypobaric hypoxia. Among Tibetan plateau peoples, these include increased vasodilation and uncoupling of erythropoiesis from hypoxia.Objective/Methods: We tested the hypothesis that these high-altitude adaptations reduce risk for hypertension and diabetes-associated anemia among the Mosuo, a Tibetan-descended population in the mountains of Southwest China that is experiencing rapid economic change and increased chronic disease risk.Results: Hypertension was substantially less common among Mosuo than lowaltitude Han populations, and models fit to the Han predicted higher probability of hypertension than models fit to the Mosuo. Diabetes was positively associated with anemia among the Han, but not the Mosuo. Conclusion:The Mosuo have lower risk for hypertension and diabetes-associated anemia than the Han, supporting the hypothesis that high-altitude adaptations affecting blood and circulation intersect with chronic disease processes to lower risk for these outcomes. As chronic diseases continue to grow as global health concerns, it is important to investigate how they may be affected by local genetic adaptations. K E Y W O R D Sanemia, diabetes, erythropoiesis, high-altitude adaptation, hypertension

Contemporary inequality exists at an unprecedented scale. Social scientists have emphasized the role played by material wealth in driving its escalation. Evolutionary anthropologists understand the drive to accumulate material wealth as one that is coupled ultimately to increasing reproductive success. Owing to biological caps on reproduction for women, the efficiency of this conversion can differ by gender, with implications for understanding the evolution of gender disparities in resource accumulation. Efficiency also differs according to the type of resources used to support reproductive success. In this paper, we review evolutionary explanations of gender disparities in resources and investigate empirical evidence to support or refute those explanations among matrilineal and patrilineal subpopulations of ethnic Chinese Mosuo, who share an ethnolinguistic identity, but differ strikingly in terms of institutions and norms surrounding kinship and gender. We find that gender differentially predicts income and educational attainment. Men were more likely to report income than women; amounts earned were higher for men overall, but the difference between men and women was minimal under matriliny. Men reported higher levels of educational attainment than women, unexpectedly more so in matrilineal contexts. The results reveal nuances in how biology and cultural institutions affect gender disparities in wealth. This article is part of the theme issue ‘Evolutionary ecology of inequality’.

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