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Humans rely on both kin and non-kin social ties for a wide range of support. In patrilocal societies that practice village exogamy, women can face the challenge of building new supportive networks when they move to their husband's village and leave many genetic kin behind. In this paper, we track how women from 10 diverse communities in rural Bangladesh build supportive networks after migrating to their husband's village, comparing their trajectories with women who remained in their childhood village (Bengali: n = 317, Santal: n = 36, Hajong: n = 39, Mandi: n = 36). Women who migrated for marriage started with almost no adult close kin (mean 0.1) compared to women who remained in their childhood village (mean 2.4). However, immigrants compensated for the lack of genetic kin by a combination of close affinal kin and close friends. By their late 20s, immigrants reported substantially more non-kin friends than did non-immigrants (mean 1.4 versus 1.1) and a comparable number of supportive partners in several domains. These findings raise questions about the functions and quality of these different social ties and how different composition of supportive networks may provide different opportunities for women in these settings. This article is part of the theme issue ‘Cooperation among women: evolutionary and cross-cultural perspectives’.

Social scientists have developed numerous asset-based wealth indices to assess and target socioeconomic inequalities globally. However, there are no systematic studies of the relative performance of these different measures as proxies for socioeconomic position. In this study, we compare how five asset-based wealth indices—the International Wealth Index (IWI), the Standard of Living portion of the Multi-Dimensional Poverty Index (MPI-SL), the Poverty Probability Index (PPI), the Absolute Wealth Estimate (AWE), and the DHS Wealth Index (DHS)—predict benchmarks of socioeconomic position across 11 communities in rural Bangladesh. All indices were highly correlated. The IWI best explained variation in individual and community ranking of economic well-being, while the PPI best explained variation both between and within communities for total household wealth and a general measure of subjective social status.

In high-income countries, poverty is often associated with higher average body mass index (BMI). To account for this reverse gradient, deprivation theories posit that declining economic resources make it more difficult to maintain a healthy weight. By contrast, discrimination theories argue that anti-fat discrimination in hiring and marriage sorts heavier individuals into lower-income households. This study assesses competing predictions of these theories by examining how household income in representative samples from South Korea (2007–2014, N=20,823) and the US (1999–2014, N=6395) is related to BMI in two key contrasting groups: (1) currently-married and (2) never-married individuals. As expected by anti-fat discrimination in marriage, the reverse gradient is observed among currently-married women but not among never-married women in both countries. Also consistent with past studies no evidence was found for a reverse gradient among men. These findings are consistent with anti-fat discrimination in marriage as a key cause of the reverse gradient and raise serious challenges to deprivation accounts as well as explanations based on anti-fat discrimination in labour markets.

Social scientists have increasingly used asset‐based wealth scores, like the Demographic and Health Survey (DHS) wealth index, to assess economic disparities. However, current indices primarily capture wealth in globalized market economies, thus ignoring other forms of prosperity, such as success in agricultural activities. Using a simple extension to the standard estimation of the DHS wealth index, we describe procedures for estimating an agricultural wealth index (AWI) that complements market‐based wealth indices by capturing household success in agricultural activities. We apply this procedure to household data from 129 DHS surveys from over 40 countries with sufficient land and livestock data to estimate a reliable and consistent AWI. We assess the construct validity of the AWI using benchmarks of growth in both adults and children. This alternative measure of wealth provides new opportunities for understanding the causes and consequences of wealth inequality, and how success along different dimensions of wealth creates different social opportunities and constraints for health and well‐being.

Hamilton's rule predicts that altruism should depend on costs incurred and benefits provided, but these depend on the relative needs of the donor and recipient. Rewriting Hamilton's rule to account for relative need suggests an amplifying effect of need on relatedness, but not necessarily other relationship qualities. In a reanalysis of three studies of social discounting and a new replication, we find that relative need amplifies the effects of relatedness on giving in two samples of U.S. adults recruited online, but not U.S. undergraduates or Indian adults recruited online. Among U.S. online participants, the effect of genetic kinship was greater when the partner was perceived to be in higher need than when in lower need. In the other samples, relatedness and greater partner need were associated with greater giving, but the effect of relatedness on giving was not significantly amplified by need. Need never amplified the effect of social closeness on giving, although it did diminish the effect of closeness in U.S. undergraduates, likely reflecting a ceiling effect. These results confirm predictions from a modification of Hamilton's rule in a sample of U.S. adults, but raise important questions about why they hold in some samples but not others. They also illustrate the importance of understanding how contextual factors, such as relative need, can moderate the importance of common variables used in evolutionary cost-benefit analyses.

OBJECTIVE: We investigate how alcohol use and friendship co-evolve during students’ transition to university. We discern effects of peer influence from friend selection based on alcohol use, whether such effects vary in strength across the school year, and whether alcohol has different effects on friendship formation versus friendship maintenance. METHOD: We gathered data on friendships, alcohol use, and binge drinking from 300 residence hall students (71% female) at a large, public U.S. university. Surveys were conducted at four time points during the 2015–2016 academic year. We used a stochastic actor-oriented model to test whether alcohol use was influenced by one’s friends, while simultaneously testing for friend selection based on alcohol use and related network processes. RESULTS: Students were 7.0 times more likely to drink alcohol weekly if all versus none of their friends drank weekly and 6.8 times more likely to binge drink when all versus none of their friends engaged in binge drinking, after we controlled for friend selection. Alcohol use differentially affected friendship creation and maintenance in a complex manner: (a) weekly drinkers were more likely to form new friendships and dissolve existing friendships than nondrinkers and (b) similarity on drinking fostered new friendships but had no effect on friendship persistence. CONCLUSIONS: Friends influence one another’s weekly drinking and binge drinking, whereas conversely, alcohol use contributes to both friendship formation and friendship instability.

Public health practitioners and social scientists frequently compare height against one-size-fits-all standards of human growth to assess well-being, deprivation, and disease risk. However, underlying differences in height can make some naturally tall populations appear well-off by universal standards, even though they live in severe states of deprivation. In this article, I describe the worldwide extent of these population differences in height and illustrate how using a universal yardstick to compare population height can create puzzling disparities (eg, between South Asia and sub-Saharan Africa) while also underestimating childhood stunting in specific world regions (eg, West Africa and Haiti). I conclude by discussing potential challenges of developing and implementing population-sensitive standards for assessing healthy development.

The relationship between material wealth and HIV infection in sub-Saharan Africa has been the subject of considerable debate in part because many studies show that wealth is positively associated with infection. Others have critiqued such results, suggesting that the widely used indicators of wealth underlying these results fail to capture the diversity of livelihood portfolios in East Africa. Using population representative data from 35,799 households in Kenya, Ethiopia, and Tanzania, we estimate household wealth along two different dimensions, associated respectively with success in wage economies and agricultural economies. Regression models for men and women show consistent and opposing associations between type of wealth and HIV infection. Controlling for age, education, and urban dwelling, increasing achievement along the wage economy dimension is positively (often significantly) associated with HIV infection. In contrast, increasing achievement along the agricultural economy dimension is often negatively associated with HIV infection, and is never associated with increased HIV risk. Interestingly, variables to assess risky sexual behaviors do not mediate the relationship between either type of wealth and HIV infection. Our results suggest that future studies on the relationship between HIV and wealth need to take into account the different dimensions of household wealth found in East African countries. Our results also generate new, important questions about why and how different forms of wealth drive HIV infection.

The many tools that social and behavioral scientists use to gather data from their fellow humans have, in most cases, been honed on a rarefied subset of humanity: highly educated participants with unique capacities, experiences, motivations, and social expectations. Through this honing process, researchers have developed protocols that extract information from these participants with great efficiency. However, as researchers reach out to broader populations, it is unclear whether these highly refined protocols are robust to cultural differences in skills, motivations, and expected modes of social interaction. In this paper, we illustrate the kinds of mismatches that can arise when using these highly refined protocols with nontypical populations by describing our experience translating an apparently simple social discounting protocol to work in rural Bangladesh. Multiple rounds of piloting and revision revealed a number of tacit assumptions about how participants should perceive, understand, and respond to key elements of the protocol. These included facility with numbers, letters, abstract number lines, and 2D geometric shapes, and the treatment of decisions as a series of isolated events. Through on-the-ground observation and a collaborative refinement process, we developed a protocol that worked both in Bangladesh and among US college students. More systematic study of the process of adapting common protocols to new contexts will provide valuable information about the range of skills, motivations, and modes of interaction that participants bring to studies as we develop a more diverse and inclusive social and behavioral science.

The increasing availability of large digital corpora of cross-linguistic data is revolutionizing many branches of linguistics. Overall, it has triggered a shift of attention from detailed questions about individual features to more global patterns amenable to rigorous, but statistical, analyses. This engenders an approach based on successive approximations where models with simplified assumptions result in frameworks that can then be systematically refined, always keeping explicit the methodological commitments and the assumed prior knowledge. Therefore, they can resolve disputes between competing frameworks quantitatively by separating the support provided by the data from the underlying assumptions. These methods, though, often appear as a ‘black box’ to traditional practitioners. In fact, the switch to a statistical view complicates comparison of the results from these newer methods with traditional understanding, sometimes leading to misinterpretation and overly broad claims. We describe here this evolving methodological shift, attributed to the advent of big, but often incomplete and poorly curated data, emphasizing the underlying similarity of the newer quantitative to the traditional comparative methods and discussing when and to what extent the former have advantages over the latter. In this review, we cover briefly both randomization tests for detecting patterns in a largely model-independent fashion and phylolinguistic methods for a more model-based analysis of these patterns. We foresee a fruitful division of labor between the ability to computationally process large volumes of data and the trained linguistic insight identifying worthy prior commitments and interesting hypotheses in need of comparison.

There is broad anthropological interest in understanding how people define "insiders" and "outsiders" and how this shapes their attitudes and behaviors toward others. As such, a suite of hypotheses has been proposed to account for the varying degrees of in-group preference between individuals and societies. We test three hypotheses related to material insecurity, pathogen stress, and views of gender equality among cross-sectional (n = 1896) and longitudinal (n = 1002) samples of young people in Ethiopia (aged 13-17 years at baseline) to explore stability and change in their preferences for coethnic spouses. We show that food insecurity is associated with a greater likelihood of intolerant mate preferences. We also find that young people who hold more gender equitable attitudes tended to hold more tolerant mate preferences. Finally, we find no support for the hypothesis that expected pathogen exposure is associated with intolerant mate preferences. Our results most strongly support a material insecurity hypothesis of in-group bias, which assumes that uncertainty over meeting basic needs leads people to favor those in their in-group. As such, our findings join a small but growing group of studies that highlight the importance of material insecurity for understanding tolerance, xenophobia, in-group bias, and favoritism.

PurposeIdentify how higher Body Mass Index (BMI) and weight discrimination are associated with romantic relationship formation and termination in young adults, and if the association was consistent for males and females.MethodsFirst-year students (N = 1096) at entry to university (Time 1) provided BMI and self-reports of weight discrimination and romantic relationship status (in a relationship vs single); 550 were successfully resampled four months later (Time 2). Logistic generalized estimating equations (GEEs) examined if Time 1 relationship status was predicted by BMI and weight discrimination. Logistic GEEs were used to determine if Time 1 BMI and weight discrimination predicted Time 2 relationship status for the strata of students in, and out, of a relationship at Time 1.ResultsAt baseline, students were less likely to be in a relationship if they had a higher BMI (OR = 0.94, 95% CI = 0.92, 0.96) or reported weight discrimination (OR = 0.69, 95% CI = 0.53, 0.90). When stratified by gender, the association between higher BMI and weight discrimination with relationship status was only observed for females. Longitudinally, a BMI-based selection effect was observed for romantic relationship formation, but not termination. Of the students who were single at Time 1, each one unit higher baseline BMI decreased the odds of the student transitioning to a relationship by 9% at Time 2 (OR = 0.91, 95% CI = 0.85, 0.96). When stratified by gender the association of higher BMI decreased odds of relationship formation was only significant for females. No weight discrimination differences for selection in or out of a romantic relationship were observed.ConclusionsThese findings suggest a weight-related selection effect for romantic relationship initiation, but not termination, in young female adults with lower BMIs. Weight discrimination was not associated with romantic relationship initiation or termination in this sample.

ObjectiveTo examine if first-year roommates made similar meal plan decisions.MethodsResidence information for 1186 first-year students (N = 593 roommate pairs) and 559 floormates was obtained for the 2015-2016 academic year. Linear generalized estimating equations (GEEs) were used to examine if the number of meals students used over the semester was higher if their roommate used their meal plan more frequently. A logistic GEE examined joint meal plan usage between students and roommates for each month of the semester. To determine if residence, rather than roommate, explained the results, a simulation was conducted by randomly assigning the floormates to a same-sex roommate.ResultsThe number of meals students used in spring was higher if the students' roommate had used more meals in spring, even after controlling for the number of meals students used in fall (Female: β = 0.07, 99% CI = 0.00, 0.13; Male: β = 0.10, 99% CI = 0.02, 0.18). Students were more likely to use a meal with their roommate if they were on the same meal plan (Female: OR = 1.61, 99% CI = 1.27, 2.04; Male: OR = 1.57, 99% CI = 1.09, 2.25), and less likely after the first month of being roommates (Female: OR = 0.57-0.25; Male: OR = 0.50-0.22; p

Studies have shown mixed associations between wealth and fertility, a finding that has posed ongoing puzzles for evolutionary theories of human reproduction. However, measures of wealth do not simply capture economic capacity, which is expected to increase fertility. They can also serve as a proxy for market opportunities available to a household, which may reduce fertility. The multifaceted meaning of many wealth measures obscures our ability to draw inferences about the relationship between wealth and fertility. Here, we disentangle economic capacity and market opportunities using wealth measures that do not carry the same market-oriented biases as commonly used asset-based measures. Using measures of agricultural and market-based wealth for 562,324 women across 111,724 sampling clusters from 151 DHS surveys in 64 countries, we employ a latent variable structural equation model to estimate (a) latent variables capturing economic capacity and market opportunity and (b) their effects on completed fertility. Market opportunities had a consistent negative effect on fertility, while economic capacity had a weaker but generally positive effect on fertility. The results show that the confusion between operational measures of wealth and the concepts of economic capacity can impede our understanding of how material resources and market contexts shape reproduction.