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Objectives Substantial inequalities in access to healthcare are common in rural and marginalized populations in the Global South, and these inequalities can drive health disparities. Historical mistrust of healthcare institutions can further impact healthcare behaviors, including vaccination. Here, we apply the concept of medical mistrust, which has been widely applied to healthcare decisions in industrialized countries, across a rural–urban spectrum of communities in Namibia, and assess its utility in understanding vaccination decisions. Methods Otjiherero-speaking indigenous communities of Kunene, Namibia, were surveyed to assess medical mistrust. Participants also answered questions about COVID-19 vaccination status, vaccine safety, and interest in a hypothetical malaria vaccine. Bayesian multilevel models were used to compare medical mistrust across communities and its influence on vaccination and vaccine perceptions. Results The level of medical mistrust varied across contexts, with the highest level of mistrust in peri-urban communities. Medical mistrust predicted beliefs about vaccine safety and interest in the malaria vaccine, but not COVID-19 vaccine status, which was largely driven by access to the vaccine. For rural and peri-urban Himba, participants also expressed disinterest in the COVID-19 vaccine and worries about its safety. Conclusion Addressing global health disparities requires understanding how locally contextualized social and ecological experiences shape healthcare and vaccination decisions. Results of this study show fundamental differences in medical mistrust by community, which may be contributing to beliefs about vaccines. Understanding how medical mistrust varies across these contexts, and how it impacts perceptions about vaccination, can inform health communication and public policy in underserved communities. 

Extensive work in the social sciences suggests that vaccination decisions are subject to incentives, biases, and social learning processes, including prestige bias transmission. High status figures, like doctors and public health officials, can be effective messengers for vaccination information and uptake under certain conditions. In communities where there is significant medical mistrust and less interaction with markets and formal medical systems, prestige bias social learning may operate through different channels. Here, we examine the role of prestige bias on vaccine decisions in two ethnic groups (Himba and Herero) with varying levels of market integration and experiences with formal healthcare systems. Participants completed a ranking task, comparing the influence of four prestigious individuals on vaccine decisions and a survey on medical mistrust. Using Plackett-Luce models, we compare the influence of location, ethnic affiliation, and other covariates on rankings. A multi-level model compared the influence of those within and outside one's ethnic group, as well as specialist (doctor/healer) and generalist (chief/governor) prestige figures. Results indicate changes in the rank of prestigious individuals across the rural-urban gradient. Our results demonstrate significant variability in prestige-biased social learning about vaccine decision making. Medical mistrust did not impact rankings. Contrary to previous work, we find that whether a prestigious individual is locally prominent is more important than their expertise in the relevant domain (health and healing). These findings emphasize the need for more context-specific studies of prestige bias, which can improve our understanding of healthcare decision-making and guide public health messaging across diverse contexts. 

Arid pastoralism is often understood as an adaptive strategy to marginal environments. As pastoralists become increasingly market integrated, novel dietary preferences and access to low quality market foods can erode traditional diets. These market‐based dietary shifts are particularly problematic during sustained drought, where reductions in traditional foods make pastoralists increasingly reliant on a cash economy. Among the Himba of the Kunene region in Namibia, colonial policies prohibiting access to livestock markets inhibit access to a cash‐based economy, leaving them vulnerable to food insecurity when nontraditional foods are needed to supplement traditional lifeways during drought. To understand the impacts of long‐term drought on diet and food insecurity, we collected longitudinal survey data on diet breadth and food insecurity across 4 years during a multi‐year drought.Participants completed a five‐item food insecurity survey and recalled diet breadth survey over the course of 4 years. Additionally, women completed a short survey of recent stressors, including health and resource stressors . We used a set of multilevel models to estimate changes in food insecurity items and diet breadth changes over the course of the study period.Multilevel models predicted score outcomes, as well as individual item responses, by year of data collection. Results indicate a 43% increase in average food insecurity and a 15% decline in average diet breadth over the study period. Dietary recall indicates that drought caused a reduction in sour milk intake, and an increase in nontraditional foods, but no change in meat or maize consumption.Conclusions Sustained drought in the Kunene region is having long‐term impacts on food insecurity, which could result in dietary shifts that outlast the current period of drought. We consider the implications of this change, especially as it relates to increasing market integration and reliance on a cash‐based over a subsistence‐based economy. 

A holistic, evolutionary framework about human cooperation must incorporate information about women's cooperative behaviour. Yet, most empirical research on human cooperation has centered on men's behaviour or been derived from experimental studies conducted in western, industrialized populations. These bodies of data are unlikely to accurately represent human behavioural diversity. To address this gap and provide a more balanced view of human cooperation, this issue presents substantial new data and multi-disciplinary perspectives to document the complexity of women's cooperative behaviour. Research in this issue 1) challenges narratives about universal gender differences in cooperation, 2) reconsiders patrilocality and access to kin as constraints on women's cooperation, 3) reviews evidence for a connection between social support and women's health and 4) examines the phylogenetic roots of female cooperation. Here, we discuss the steps taken in this issue toward a more complete and evidence-based understanding of the role that cooperation plays in women's and girls' lives and in building human sociality. This article is part of the theme issue ‘Cooperation among women: evolutionary and cross-cultural perspectives’. 

While it is commonly assumed that farmers have higher, and foragers lower, fertility compared to populations practicing other forms of subsistence, robust supportive evidence is lacking. We tested whether subsistence activities—incorporating market integration—are associated with fertility in 10,250 women from 27 small-scale societies and found considerable variation in fertility. This variation did not align with group-level subsistence typologies. Societies labeled as “farmers” did not have higher fertility than others, while “foragers” did not have lower fertility. However, at the individual level, we found strong evidence that fertility was positively associated with farming and moderate evidence of a negative relationship between foraging and fertility. Markers of market integration were strongly negatively correlated with fertility. Despite strong cross-cultural evidence, these relationships were not consistent in all populations, highlighting the importance of the socioecological context, which likely influences the diverse mechanisms driving the relationship between fertility and subsistence. 

To address claims of human exceptionalism, we determine where humans fit within the greater mammalian distribution of reproductive inequality. We show that humans exhibit lower reproductive skew (i.e., inequality in the number of surviving offspring) among males and smaller sex differences in reproductive skew than most other mammals, while nevertheless falling within the mammalian range. Additionally, female reproductive skew is higher in polygynous human populations than in polygynous nonhumans mammals on average. This patterning of skew can be attributed in part to the prevalence of monogamy in humans compared to the predominance of polygyny in nonhuman mammals, to the limited degree of polygyny in the human societies that practice it, and to the importance of unequally held rival resources to women’s fitness. The muted reproductive inequality observed in humans appears to be linked to several unusual characteristics of our species—including high levels of cooperation among males, high dependence on unequally held rival resources, complementarities between maternal and paternal investment, as well as social and legal institutions that enforce monogamous norms.