Medical mistrust, discrimination and healthcare experiences in a rural Namibian community.

Substantial evidence indicates that medical mistrust, resulting from experiences with discrimination and marginalisation, is a determinant of health disparities in minority populations. However, this research is largely limited to the US and other industrialised countries. To broaden our understanding of the role of medical mistrust on health-care decision making, we conducted a study on healthcare experiences and perceptions in a rural, underserved indigenous community in northwest Namibia (n = 86). Mixing semi-structured interview questions with the medical mistrust index (MMI), we aim to determine the relevance of the MMI in a non-industrialised population and compare index scores with reports of healthcare experiences. We find that medical mistrust is a salient concept in this community, mapping onto negative healthcare experiences and perceptions of discrimination. Reported healthcare experiences indicate that perceived incompetence, maltreatment and discrimination drive mistrust of medical personnel. However, reporting of recent healthcare experiences are generally positive. Our results indicate that the concept of medical mistrust can be usefully applied to communities in the Global South. These populations, like minority communities in the US, translate experiences of discrimination and marginalisation into medical mistrust. Understanding these processes can help address health disparities and aid in effective public health outreach in underserved populations.

Women's subsistence strategies predict fertility across cultures, but context matters.

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.

Remote sensing evidence for population growth of isolated indigenous societies in Amazonia.

Isolated indigenous societies who actively avoid sustained peaceful contact with the outside world are critically endangered. Last year, "Tanaru", the lone surviving man of his tribe for at least 35 years, died in Southwest Amazonia, marking the latest cultural extinction event in a long history of massacres, enslavement, and epidemics. Yet in the upper reaches of the Amazon Basin, dozens of resilient isolated tribes still manage to survive. Remote sensing is a reliable method of monitoring the population dynamics of uncontacted populations by quantifying the area cleared for gardens and villages, along with the fire detections associated with the burning of those clearings. Remote sensing also provides a method to document the number of residential structures and village fissioning. Only with these longitudinal assessments can we better evaluate the current no-contact policies by the United Nations and governments, along with the prospects for the long-term survival of isolated tribes. While the world's largest isolated indigenous metapopulation, Pano speakers in Acre, Brazil, appears to be thriving, other smaller isolated populations disconnected from metapopulations continue to be extremely vulnerable to external threats. Our applied anthropological conservation approach is to provide analyses of publicly available remote sensing datasets to help inform policies that enhance the survival and well-being of isolated cultural groups.

Only Death Will Separate Us: The Role of Extramarital Partnerships among Himba Pastoralists.

Extramarital partnerships are highly stigmatized in many societies and are typically excluded from studies of family dynamics and social support. Nevertheless, in many societies such relationships are common and can have important impacts on resource security and health outcomes. However, current studies of these relationships come mainly from ethnographic studies, with quantitative data extremely rare. Here we present data from a 10-year study of romantic partnerships among a community of Himba pastoralists in Namibia, where concurrency is common. The majority of married men (97%) and women (78%) currently reported having more than one partner (n = 122). Using multilevel models comparing marital and nonmarital relationships, we found that, contrary to conventional wisdom surrounding concurrency, Himba form enduring bonds with extramarital partners that often last decades and are very similar to marital ones in terms of length, emotional affect, reliability, and future prospects. Qualitative interview data showed that extramarital relationships were imbued with a set of rights and obligations that, while distinct from those of spouses, provide an important source of support. Greater inclusion of these relationships in studies of marriage and family would provide a clearer picture of social support and resource transfers in these communities and help to explain variation in the practice and acceptance of concurrency around the world.

Examination of runs of homozygosity in relation to height in an endogamous Namibian population.

OBJECTIVES: Height is a complex, highly heritable polygenic trait subject to both genetic composition and environmental influences. Recent studies suggest that a large proportion of height heritability is determined by the cumulative effect of many low allele frequency variants across the genome. Previous research has also identified an inverse relationship between height and runs of homozygosity (ROH); however, this has yet to be examined within African populations. We aim to identify this association within the Himba, an endogamous Namibian population who are recently bottlenecked, resulting in elevated haplotype sharing and increased homozygosity. MATERIALS AND METHODS: Here, we calculate the fraction of the genome composed of long runs of homozygosity (FROH) in a sample of 245 adults and use mixed effects models to assess its effect on height. RESULTS: We find that Himba adults exhibit increased homozygosity. However, in contrast to previous studies in other populations, we do not find a significant effect of FROH on height within the Himba. We further estimated heritability of height, noting both an enrichment of distant relatives and greater developmental homogeneity across households; we find that h g 2 = 0.59 (SE ± 0.146), comparable to estimates reported in Europeans. DISCUSSION: Our results may be due to other environmental variables we were not able to include, measurement error, or low statistical power, but may also imply that phenotypic expression resulting from increased homozygosity may vary from population to population.

The dietary impacts of drought in a traditional pastoralist economy.

OBJECTIVES: 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. METHODS: Participants completed a five-item food insecurity survey and recalled diet breadth survey over the course of 4 years (N = 191-234). Additionally, women completed a short survey of recent stressors, including health and resource stressors (N = 127). 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. RESULTS: 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.

The effect of mating market dynamics on partner preference and relationship quality among Himba pastoralists.

Relative mate value has long been believed to be a critical component of mate choice in humans. However, most empirical work focuses on preferences rather than actual pair formation, and data connecting partner preferences, partnership formation, and relationship quality remain rare. Here, we estimate mate value using >12,000 ratings by opposite-sex, in-group members to understand both hypothetical partnership preferences and actualized relationship dynamics. When evaluating hypothetical partnerships, people generally prefer individuals whose mate value is higher than their own, indicating an aspirational matching strategy. However, mate value comparisons of individuals in marital and nonmarital relationships show a positive correlation, suggesting that individuals tend to pair up with similarly desirable individuals. Furthermore, despite aspirational preferences, couples who are more closely matched reported greater relationship quality, measured through frequency of interactions, reported sexual histories, and partnership length.

Navigating cross-cultural research: methodological and ethical considerations.

The intensifying pace of research based on cross-cultural studies in the social sciences necessitates a discussion of the unique challenges of multi-sited research. Given an increasing demand for social scientists to expand their data collection beyond WEIRD (Western, educated, industrialized, rich and democratic) populations, there is an urgent need for transdisciplinary conversations on the logistical, scientific and ethical considerations inherent to this type of scholarship. As a group of social scientists engaged in cross-cultural research in psychology and anthropology, we hope to guide prospective cross-cultural researchers through some of the complex scientific and ethical challenges involved in such work: (a) study site selection, (b) community involvement and (c) culturally appropriate research methods. We aim to shed light on some of the difficult ethical quandaries of this type of research. Our recommendation emphasizes a community-centred approach, in which the desires of the community regarding research approach and methodology, community involvement, results communication and distribution, and data sharing are held in the highest regard by the researchers. We argue that such considerations are central to scientific rigour and the foundation of the study of human behaviour.

Why men invest in non-biological offspring: paternal care and paternity confidence among Himba pastoralists.

Paternal investment is predicted to be a facultative calculation based on expected fitness returns and modulated by a host of social predictors including paternity uncertainty. However, the direct role of paternity confidence on the patterns of paternal investment is relatively unknown, in part due to a lack of research in populations with high levels of paternity uncertainty. Additionally, much of the work on paternity certainty uses cues of paternity confidence rather than direct assessments from fathers. We examine the effect of paternity assertions on the multiple measures of paternal investment in Himba pastoralists. Despite a high degree of paternity uncertainty, Himba have strong norms associated with social fatherhood, with men expected to invest equally in biological and non-biological offspring. Our behavioural data show patterns that largely conform to these norms. For domains of investment that are highly visible to the community, such as brideprice payments, we find no evidence of investment biased by paternity confidence. However, more private investment decisions do show some evidence of sex-specific titration. We discuss these results in light of broader considerations about paternal care and the mating-parenting trade-off.

The ethics and logistics of field-based genetic paternity studies.

The rapidly decreasing costs of generating genetic data sequencing and the ease of new DNA collection technologies have opened up new opportunities for anthropologists to conduct field-based genetic studies. An exciting aspect of this work comes from linking genetic data with the kinds of individual-level traits evolutionary anthropologists often rely on, such as those collected in long-term demographic and ethnographic studies. However, combining these two types of data raises a host of ethical questions related to the collection, analysis and reporting of such data. Here we address this conundrum by examining one particular case, the collection and analysis of paternity data. We are particularly interested in the logistics and ethics involved in genetic paternity testing in the localized settings where anthropologists often work. We discuss the particular issues related to paternity testing in these settings, including consent and disclosure, consideration of local identity and beliefs and developing a process of continued community engagement. We then present a case study of our own research in Namibia, where we developed a multi-tiered strategy for consent and community engagement, built around a double-blind procedure for data collection, analysis and reporting.

Resource demands reduce partner discrimination in Himba women.

Where autonomy for partner choice is high, partner preferences may be shaped by both social and ecological conditions. In particular, women's access to resources can influence both the type and number of partnerships she engages in. However, most existing data linking resources and partner choice rely on either priming effects or large demographic databases, rather than preferences for specific individuals. Here we leverage a combination of demographic data, food insecurity scores and trait and partner preference ratings to determine whether resource security modulates partner preferences among Himba pastoralists. We find that while food insecurity alone has a weak effect on women's openness to new partners, the interaction of food insecurity and number of dependent children strongly predicts women's openness to potential partners. Further, we show that women who have more dependants have stronger preferences for wealthy and influential men. An alternative hypothesis derived from mating-market dynamics, that female desirability affects female preferences, had no effect. Our data show that women who face greater resource constraints are less discriminating in the number of partners they are open to, and have stronger preferences for resource-related traits. These findings highlight the importance of ecological signals in explaining the plasticity of mate preferences.

Patterns of paternal investment predict cross-cultural variation in jealous response.

Long-lasting, romantic partnerships are a universal feature of human societies, but almost as ubiquitous is the risk of instability when one partner strays. Jealous response to the threat of infidelity is well studied, but most empirical work on the topic has focused on a proposed sex difference in the type of jealousy (sexual or emotional) that men and women find most upsetting, rather than on how jealous response varies1,2. This stems in part from the predominance of studies using student samples from industrialized populations, which represent a relatively homogenous group in terms of age, life history stage and social norms3,4. To better understand variation in jealous response, we conducted a 2-part study in 11 populations (1,048 individuals). In line with previous work, we find a robust sex difference in the classic forced-choice jealousy task. However, we also show substantial variation in jealous response across populations. Using parental investment theory, we derived several predictions about what might trigger such variation. We find that greater paternal investment and lower frequency of extramarital sex are associated with more severe jealous response. Thus, partner jealousy appears to be a facultative response, reflective of the variable risks and costs of men's investment across societies.

The disequilibrium of double descent: changing inheritance norms among Himba pastoralists.

Matrilineal systems in sub-Saharan Africa tend to co-occur with horticulture and are rare among pastoralists, with the causal arrow pointing from the introduction of cattle to the loss of matriliny. However, most work on this topic stems from either phylogenetic analyses or historical data. To better understand the shift from matrilineal to patrilineal inheritance that occurred among Bantu populations after the adoption of pastoralism, data from societies that are currently in transition are needed. Himba pastoralists, who practice 'double descent', may represent one such society. Using multi-generational ethnography and structured survey data, we describe current norms and preferences about inheritance, as well as associated norms related to female autonomy. We find that preferences for patrilineal inheritance are strong, despite the current practice of matrilineal cattle inheritance. We also find that a preference for patriliny predicts greater acceptance of norm violating behaviour favouring sons over nephews. Finally, we show that there are important generational differences in how men view women's autonomy, which are probably attributable to both changing norms about inheritance and exposure to majority-culture views on women's roles. Our data shed light on how systemic change like the shifts in descent reckoning that occurred during the Bantu expansion can occur. This article is part of the theme issue 'The evolution of female-biased kinship in humans and other mammals'.

The influence of age- and sex-specific labor demands on sleep in Namibian agropastoralists.

OBJECTIVE: To understand the basics of sleep quality in a pastoralist population and to explore predictors of this variation. DESIGN: Cross-sectional. SETTING: Northern Namibia, dry seasons of 2016 and 2017. PARTICIPANTS: The Himba, a nonindustrial seminomadic agropastoralist population without access to the electrical grid. MEASUREMENTS: Using Actiwatch-2 devices, 75 participants completed 721 days of wear. We calculated sleep duration, efficiency, and activity counts before and after sunset/sunrise and onset/offset. Participants were also interviewed about sleeping arrangements and nighttime disruptions. RESULTS: Himba show lower sleep duration and efficiency than other populations studied, and men had substantially lower duration and efficiency than women. Sex differences were not attenuated when napping was included with total sleep time. Age predicted longer sleep duration and lower evening and morning activity levels. Number of adult co-sleepers predicted increased sleep duration and efficiency in women. Livestock disturbance was not a commonly reported cause of nighttime waking. CONCLUSIONS: These findings support predictions that pastoralist groups may have lower sleep quality than other subsistence populations, but this does not appear to be a consequence of noise from livestock. Instead, lower sleep quality appears to be the result of subsistence and social activities, particularly for men and young adults overall.

DHEA Modulates Immune Function: A Review of Evidence.

DHEA and DHEA-S have numerous associations with multiple aspects of immune function and are often characterized as beneficial and supportive of immunocompetence. However, closer inspection of these studies reveals confusion regarding the immunological components modified, the mechanisms of action, and degree of impact, and even whether these hormones even have direct action or are mediated by metabolites and interactions with other hormones and hormone receptors. Additionally, much of the research is conducted on rodent models using very high concentrations of hormone supplements, which may not be representative of the effects of these hormones in natural circulating concentrations, or may not translate to human physiology in a meaningful way. Here, we review the effects of DHEA and DHEA-S on immune function and examine the potential roles these hormones play on specific components of immune function. Drawing from the literature on hormone supplementation, as well as studies examining the natural circulating levels of DHEA and DHEA-S on specific immunological components and disease processes, we argue that DHEA has differential actions on human immune function, and that its effects are further shaped by concentrations of other hormones. Of particular interest is the role of DHEA as an antiglucocorticoid, and for its actions on both androgen and estrogen receptors. With additional research, DHEA may be useful as a therapeutic, particularly in diseases with high levels of inflammation, or where adrenal production is altered. The convoluted nature of DHEA-immune interactions makes direct effects difficult to interpret, and future research needs to consider direct, intracrine, and downstream effects of these hormones.

Short-term resource allocation during extensive athletic competition.

OBJECTIVES: Following predictions from life history theory, we sought to identify acute trade-offs between reproductive effort (as measured by psychological arousal) and somatic maintenance (via functional measures of innate immunity) during conditions of severe energetic imbalance. METHODS: Sixty-six male ultramarathon runners (ages 20 to 37 years) were sampled before and after a lengthy race. Saliva and sera were collected for testosterone and immunological analyses (hemolytic complement activity and bacterial killing ability). Lean body mass was assessed by bioelectrical impedance, and libido was measured using a slideshow of arousing and neutral images. RESULTS: Following predictions, there was a significant decrease in salivary testosterone levels (109.59 pg/mL versus 97.61 pg/mL, P < .001) and arousal scores in response to provocative images (5.40 versus 4.89, P = .001) between prerace and postrace time points. Additionally, participant bacterial killing ability (P = .035) and hemolytic complement activity (P = .021) increased between prerace and postrace. CONCLUSIONS: Decreased libido and testosterone with concomitant heightened innate immune responses suggest a shift in energetic priorities away from reproduction and toward maintenance/defense during a period of energetic stress.

A Survey of Perceived Effectiveness of Part 4 Maintenance of Certification.

OBJECTIVES: Evaluative assessment is needed to inform improvement of Part 4 Maintenance of Certification (MOC), a large-scale program that aims to improve physician knowledge, engagement, and skills in quality improvement (QI). We sought to determine if Part 4 MOC participation improves perceived educational and clinical outcomes by piloting a new physician survey. METHODS: We administered a new online survey (MOC Practice, Engagement, Attitude, and Knowledge Survey) to physicians at the beginning and end of a Part 4 MOC project sponsored by a pediatric hospital's American Board of Medical Specialties' portfolio program during 2015. Participants worked in academic and community settings and in various accredited specialties. The main outcome was change in survey response on a 5-point Likert scale (1 = best) for 3 learning domains (QI engagement and attitude; QI method application, and improved patient care). RESULTS: Of 123 complete responses and a 97% response rate, mean baseline responses were positive or neutral (2.2, 2.3, 1.9, respectively). Responses improved in QI engagement and attitude (-0.15, z score = -2.78, P = .005), QI method application (-0.39, z score = -7.364, P < .005), and improved patient care (-0.11, z score = -1.728, P = .084). CONCLUSIONS: A Part 4 MOC physician survey provides valuable data to evaluate and improve the learning activity. In this children's hospital program, physicians view Part 4 favorably. Participation was associated with modest improvements in perceptions of QI engagement and attitude, application of QI methods, and patient care. Systematic evaluation of all Part 4 MOC projects and programs has the potential to improve the program nationally.

Child fosterage and sex-biased nutritional outcomes among Namibian pastoralists.

OBJECTIVES: Across cultures, fosterage has been shown to impact child health. Contextual factors, such as the reason for fosterage and the relationship between foster parent and child, are known to magnify variance in nutritional outcomes for foster children. Another important, but less studied, factor is the role of gender. Sex-biases in physiology and cultural norms are both known to affect child nutrition, and we posit these effects might be magnified in the presence of fosterage. In this study, we investigate how sex interacts with fosterage to affect nutritional outcomes among Namibian pastoralists. METHODS: Anthropometrics for children and adults were collected using standard procedures, and linear models were used to predict the effects of age, sex, and fosterage on height, weight, and body mass index Z-scores. Semi-structured interviews with adults provided context for understanding sex specific reasons for fosterage and biases in investment. RESULTS: Boys in this population have lower nutritional scores than girls, and fostered boys have lower weight and BMI Z-scores than nonfostered boys. Fostered girls have lower height Z-scores and are more likely to be stunted and underweight than nonfostered girls. These effects extend into adulthood, with fostered women being shorter than their nonfostered counterparts. CONCLUSIONS: Sex plays a role in the nutritional impact of fosterage among Himba children. These differences could be related to differential child labor demands, investment patterns, and the divergent reasons girls and boys are placed into fosterage. Future studies should consider how fosterage can magnify existing biases, like sex, when studying its impact on child health.

Adrenal maturation, nutritional status, and mucosal immunity in Bolivian youth.

OBJECTIVES: Humans-and several other apes-exhibit a unique pattern of post-natal adrenal maturation; however, the causes and consequences of variation in adrenal development are not well understood. In this study, we examine developmental and age-related maturation of the adrenal gland (measured via dehydroepiandrosterone-sulfate [DHEA-S]) for potential life-history associations with growth and mucosal immunity in a rural population of immune-challenged Bolivian juveniles and adolescents. METHODS: Salivary DHEA-S, anthropometrics, and salivary mucosal immunity (secretory IgA [sIgA]) were measured in 171 males and females, aged 8-23. RESULTS: Males with greater energy (i.e. fat) stores showed higher DHEA-S levels. Controlling for age and energetic condition (to control for phenotypic correlation), higher DHEA-S was associated with higher mucosal immunity (sIgA) among both males and females. Higher DHEA-S levels were positively associated with growth (i.e. height and strength) in males. CONCLUSIONS: In accordance with predictions derived from life-history theory, males with higher energy stores secrete more adrenal androgens. This suggests that adrenal maturation is costly and subject to constraints; that is, only males with sufficient reserves will invest in accelerated adrenal maturation. Further, DHEA-S appears to have a measureable influence on immunocompetence in adolescent males and females; therefore, deficits in DHEA-S may have important consequences for health and maturation during this period. Adrenal maturation is an important, but understudied component of human growth and development.

The role of dehydroepiandrosterone on functional innate immune responses to acute stress.

The androgen dehydroepiandrosterone (DHEA) responds to stress activation, exhibits anti-glucocorticoid properties, and modulates immunity in diverse ways, yet little is known of its role in acute stress responses. In this study, the effects of DHEA and its sulfate ester DHEA-S on human male immune function during exposure to an acute stressor is explored. Variation in DHEA, DHEA-S, testosterone, and cortisol, along with bacterial killing assays, was measured in response to a modified Trier Social Stress test in 27 young adult males. Cortisol was positively related to salivary innate immunity but only for participants who also exhibited high DHEA responses. Additionally, DHEA positively and DHEA-S negatively predicted salivary immunity, but the opposite was observed for serum-based innate immunity. The DHEA response to acute stress appears to be an important factor in stress-mediated immunological responses, with differential effects on immunity dependent upon the presence of other hormones, primarily cortisol and DHEA-S. These results suggest that DHEA plays an important role, alongside other hormones, in modulating immunological shifts during acute stress.