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Objectives: Studies suggest that living at high altitude decreases obesity risk, but this research is limited to single-country analyses. We examine the relationship between altitude and body mass index (BMI) among women living in a diverse sample of low- and middle-income countries., Materials and Methods: Using Demographic and Health Survey data from 1 583 456 reproductive age women (20-49 years) in 54 countries, we fit regression models predicting BMI and obesity by altitude controlling for a range of demographic factors-age, parity, breastfeeding status, wealth, and education., Results: A mixed-effects model with country-level random intercepts and slopes predicts an overall -0.162 kg/m 2 (95% CI -0.220, -0.104) reduction in BMI and lower odds of obesity (OR 0.90, 95% CI 0.87, 0.95) for every 200 m increase in altitude. However, countries vary dramatically in whether they exhibit a negative or positive association between altitude and BMI (34 countries negative, 20 positive). Mixed findings also arise when examining odds of obesity., Discussion: We show that past findings of declining obesity risk with altitude are not universal. Increasing altitude predicts slightly lower BMIs at the global level, but the relationship within individual countries varies in both strength and direction., (© 2024 Wiley Periodicals LLC.)

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'.

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., (© 2020 Wiley Periodicals LLC.)

Background: Valid measurement of hemoglobin is important for tracking and targeting interventions. This study compares hemoglobin distributions between surveys matched by country and time from The Demographic and Health Survey (DHS) Program and the Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project., Methods: Four pairs of nationally representative surveys measuring hemoglobin using HemoCue® with capillary (DHS) or venous (BRINDA) blood were matched by country and time. Data included 17,719 children (6-59 months) and 21,594 non-pregnant women (15-49 y). Across paired surveys, we compared distributional statistics and anemia prevalence., Results: Surveys from three of the four countries showed substantial differences in anemia estimates (9 to 31 percentage point differences) which were consistently lower in BRINDA compared to DHS (2 to 31 points for children, 1 to 16 points for women)., Conclusion: We identify substantial differences in anemia estimates from surveys of similar populations. Further work is needed to identify the cause of these differences to improve the robustness of anemia estimates for comparing populations and tracking improvements over time.

Objectives: Current standards for comparing stunting across human populations assume a universal model of child growth. Such comparisons ignore population differences that are independent of deprivation and health outcomes. This article partitions variation in height-for-age that is specifically associated with deprivation and health outcomes to provide a basis for cross-population comparisons., Materials and Methods: Using a multilevel model with a sigmoid relationship of resources and growth, we partition variation in height-for-age z-scores (HAZ) from 1.5 million children across 70 countries into two components: (1) "accrued HAZ" shaped by environmental inputs (e.g., undernutrition, infectious disease, inadequate sanitation, poverty) and (2) a country-specific "basal HAZ" independent of such inputs. We validate these components against population-level infant mortality rates and assess how these basal differences may affect cross-population comparisons of stunting., Results: Basal HAZ differs reliably across countries (range of approximately 1.5 SD) and is independent of measures of infant mortality. By contrast, accrued HAZ captures stunting as impaired growth due to deprivation and is more closely associated with infant mortality than observed HAZ. Assessing stunting prevalence by accrued HAZ suggest that populations in West Africa and Haiti suffer much greater levels of stunting than indicated by observed HAZ., Discussion: Current universal standards may dramatically underestimate stunting in populations with taller basal HAZ. Relying on observed HAZ rather than accrued HAZ may also lead to inappropriate cross-population comparisons, such as concluding that Haitian children enjoy better conditions for growth than do Indian or Guatemalan children., (© 2019 Wiley Periodicals, Inc.)

Objectives: Lack of wealth (poverty) impacts almost every aspect of human biology. Accordingly, many studies include its assessment. In almost all cases, approaches to assessing poverty are based on lack of success within cash economies (eg, lack of income, employment). However, this operationalization deflects attention from alternative forms of poverty that may have the most substantial influence on human wellbeing. We test how a multidimensional measure of poverty that considers agricultural assets expands the explanatory power of the construct of household poverty by associating it with one key aspect of wellbeing: symptoms of mental health., Methods: We used the case of three highly vulnerable but distinctive communities in Haiti-urban, town with a rural hinterland, and rural. Based on survey responses from adults in 4055 geographically sampled households, linear regression models were used to predict depression and anxiety symptom levels controlling for a wide range of covariates related to detailed measures of material poverty, including cash-economy and agricultural assets, income, financial stress, and food insecurity., Results: Household assets related to the cash economy were significantly associated with lower (ie, better) depression scores (-0.7, [95% CI: -1.2 to, -0.1]) but unrelated to anxiety scores (-0.3 [95% CI: -0.8 to 0.3]). Agricultural wealth was significantly-and more strongly-associated with both reductions in depression symptoms (-1.4 [95% CI: -2.2 to -0.7]) and anxiety symptoms (-1.8 [95% CI: -2.6 to -1.0]). These associations were consistent across the three sites, except in the fully urban site in Port-au-Prince where level of depression symptoms was not significantly associated with household agricultural wealth., Conclusions: Standard measures of poverty based on success in the cash economy can mask important associations between poverty and wellbeing, in this case related to household-level subsistence capacity and crucial food-producing household assets., (© 2019 Wiley Periodicals, Inc.)

Contemporary humans occupy the widest range of socioeconomic environments in their evolutionary history, and this has revealed unprecedented environmentally-induced plasticity in physical growth. This plasticity also has limits, and identifying those limits can help researchers: (1) parse when population differences arise from environmental inputs or not and (2) determine when it is possible to infer socioeconomic disparities from disparities in body form. To illustrate potential limits to environmental plasticity, we analyze body mass index (BMI) and height data from 1,768,962 women and 207,341 men (20-49 y) living in households exhibiting 1000-fold variation in household wealth (51 countries, 1985-2017, 164 surveys) across four world regions-sub-Saharan Africa, South Asia, Latin America, and North Africa and the Middle East. We find that relationships of environmental inputs with both mean height and BMI bottom out at roughly 100-700 USD per capita household wealth (2011 international units, PPP), but at different basal BMIs and basal heights for different regions. The relationship with resources tops out for BMI at around 20 K-35 K USD for women, with growth potential due to environmental inputs in the range of 6.2-8.4 kg/m 2 . By contrast, mean BMI for men and mean height for both sexes remains sensitive to environmental inputs even at levels far above the low- and middle-income samples studied here. This suggest that further work integrating comparable data from low- and high-income samples should provide a better picture of the full range of environmental inputs on human height and BMI. We conclude by discussing how neglecting such population-specific limits to human growth can lead to erroneous inferences about population differences., (Copyright © 2018 Elsevier B.V. All rights reserved.)

A key demographic hypothesis has been that fertility declines rely on stopping at target parities, but emerging evidence suggests that women frequently reduce fertility without specific numeric targets. To assess the relative importance of these two paths to fertility decline, we develop a novel mixture model to estimate: (1) the proportion of women who stop at a target parity; and (2) mean completed fertility among those who do not. Applied to Demographic and Health Survey data from women aged 45-49 in 84 low- and middle-income countries, and to United States Census cohorts, the model shows considerable variation in the proportion stopping at specific parities (1-84 per cent). The estimates also show that declines in completed fertility are largely attributable to women who do not stop at target parities, suggesting that stopping at ideal parities may be less important than parity-independent decisions for a wide range of fertility transitions.

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., Competing Interests: The authors declare no conflict of interest.

Competing Interests: The authors declare no conflict of interest.

Aim: To test whether a risk of child illness is best predicted by deviations from a population-specific growth distribution or a universal growth distribution., Subjects and Methods: Child weight for height and child illness data from 433 776 children (1-59 months) from 47 different low and lower income countries are used in regression models to estimate for each country the child basal weight for height. This study assesses the extent to which individuals within populations deviate from their basal slenderness. It uses correlation and regression techniques to estimate the relationship between child illness (diarrhoea, fever or cough) and basal weight for height, and residual weight for height., Results: In bivariate tests, basal weight for height z-score did not predict the country level prevalence of child illness (r 2  = -0.01, n = 47, p = 0.53), but excess weight for height did (r 2  = 0.14, p < 0.01). At the individual level, household wealth is negatively associated with the odds that a child is reported as ill (beta = -0.04, p < 0.001, n = 433 776) and basal weight for height was not (beta = 0.20, p = 0.27). Deviations from country-specific basal weight for height were negatively associated with the likelihood of illness (beta = -0.13, p < 0.01), indicating a 13% reduction in illness risk for every 0.1 standard deviation increase in residual weight-for-height Conclusion: These results are consistent with the idea that populations may differ in their body slenderness, and that deviations from this body form may predict the risk of childhood illness.

Material wealth is a key factor shaping human development and well-being. Every year, hundreds of studies in social science and policy fields assess material wealth in low- and middle-income countries assuming that there is a single dimension by which households can move from poverty to prosperity. However, a one-dimensional model may miss important kinds of prosperity, particularly in countries where traditional subsistence-based livelihoods coexist with modern cash economies. Using multiple correspondence analysis to analyze representative household data from six countries-Nepal, Bangladesh, Ethiopia, Kenya, Tanzania and Guatemala-across three world regions, we identify a number of independent dimension of wealth, each with a clear link to locally relevant pathways to success in cash and agricultural economies. In all cases, the first dimension identified by this approach replicates standard one-dimensional estimates and captures success in cash economies. The novel dimensions we identify reflect success in different agricultural sectors and are independently associated with key benchmarks of food security and human growth, such as adult body mass index and child height. The multidimensional models of wealth we describe here provide new opportunities for examining the causes and consequences of wealth inequality that go beyond success in cash economies, for tracing the emergence of hybrid pathways to prosperity, and for assessing how these different pathways to economic success carry different health risks and social opportunities.

The target article proposes the insurance hypothesis as an explanation for higher levels of obesity among food-insecure women living in high-income countries. An alternative hypothesis based on anti-fat discrimination in marriage can also account for such correlations between poverty and obesity and is more consistent with finer-grained analyses by marital status, gender, and age.

Gervais & Fessler dissect the folk concept of "contempt" to argue for a functionally integrated model of attitudes and emotions in the context of social relationships. Existing studies of how evaluations of warmth, competence, and closeness shape people's reactions and behaviors towards others may help in operationalizing and testing the proposed model.

Each year, hundreds of articles in population health and nutrition, many in high-profile journals, use standard cutoffs based on weight and height as assessments of obesity and undernutrition. These global efforts to monitor overweight and underweight often rest on the assumption that ethnic differences in underlying body form are sufficiently small to permit universal anthropometric cutoffs for comparing excess and insufficient body fat across populations. However, a century of work in human biological variation suggests that human populations can vary dramatically in underlying body form in a way that may require population-sensitive cutoffs for monitoring. Here, we describe recently developed methods that can provide population-sensitive assessments of both excess and insufficient energy reserves in a wide range of countries. We use this approach to illustrate how worldwide variation in human body form is far more widespread than previously thought, and that it can occur at several geographic scales, including the level of world regions, countries and populations within countries. The findings also suggest that using standard cutoffs that ignore this variation can underestimate current obesity levels in adults by more than 400-500 million while also incorrectly prioritizing high-risk areas for undernutrition in children in key regions around the world., (© 2016 The Authors. Obesity Reviews published by John Wiley & Sons Ltd on behalf of World Obesity Federation.)

Most work on the human fertility transition has focused on declines in mean fertility. However, understanding changes in the variance of reproductive outcomes can be equally important for evolutionary questions about the heritability of fertility, individual determinants of fertility and changing patterns of reproductive skew. Here, we document how variance in completed fertility among women (45-49 years) differs across 200 surveys in 72 low- to middle-income countries where fertility transitions are currently in progress at various stages. Nearly all (91%) of samples exhibit variance consistent with a Poisson process of fertility, which places systematic, and often severe, theoretical upper bounds on the proportion of variance that can be attributed to individual differences. In contrast to the pattern of total variance, these upper bounds increase from high- to mid-fertility samples, then decline again as samples move from mid to low fertility. Notably, the lowest fertility samples often deviate from a Poisson process. This suggests that as populations move to low fertility their reproduction shifts from a rate-based process to a focus on an ideal number of children. We discuss the implications of these findings for predicting completed fertility from individual-level variables., (© 2016 The Author(s).)

Objectives: One of the fundamental tradeoffs posited in life history theory is between storing energy for future reproduction versus spending that energy on current reproduction. However, past studies have shown variable and sometimes contradictory effects of reproduction on energy stores among women., Methods: To examine how varying economic resources can account for these diverse findings, we applied mixed models to Demographic and Health Survey (DHS) data from 187,848 nulliparous and primiparous women of reproductive age (20-34 years) in 65 countries varying widely in economic resources. Using this approach, we tracked average trajectories of body mass through pregnancy and the post-partum period, and assessed how these trajectories varied by household wealth and breastfeeding., Results: In all four wealth categories, sustained breastfeeding posed a substantial tradeoff with energy stores, reducing post-partum BMI by 0.5 to 1.0 kg m(-2) relative to non-breastfeeding women. However, among the wealthiest households (>6,400 USD per capita), this deficit was buffered substantially by greater pre-partum weight gain (+1.1 kg m(-2) compared to women from the poorest households)., Conclusion: These findings show how the level of economic resources can systematically and profoundly shape a physiological tradeoff in reproduction, and can help account for past contradictory findings. More broadly, these results illustrate how integrating economic and energetic resources in a common framework can help clarify the apparently disparate weight-related outcomes of fertility in different countries., (© 2015 Wiley Periodicals, Inc.)

Objective: To estimate the absolute wealth of households using data from demographic and health surveys., Methods: We developed a new metric, the absolute wealth estimate, based on the rank of each surveyed household according to its material assets and the assumed shape of the distribution of wealth among surveyed households. Using data from 156 demographic and health surveys in 66 countries, we calculated absolute wealth estimates for households. We validated the method by comparing the proportion of households defined as poor using our estimates with published World Bank poverty headcounts. We also compared the accuracy of absolute versus relative wealth estimates for the prediction of anthropometric measures., Findings: The median absolute wealth estimates of 1,403,186 households were 2056 international dollars per capita (interquartile range: 723-6103). The proportion of poor households based on absolute wealth estimates were strongly correlated with World Bank estimates of populations living on less than 2.00 United States dollars per capita per day (R(2)  = 0.84). Absolute wealth estimates were better predictors of anthropometric measures than relative wealth indexes., Conclusion: Absolute wealth estimates provide new opportunities for comparative research to assess the effects of economic resources on health and human capital, as well as the long-term health consequences of economic change and inequality.

Contemporary human populations conform to ecogeographic predictions that animals will become more compact in cooler climates and less compact in warmer ones. However, it remains unclear to what extent this pattern reflects plastic responses to current environments or genetic differences among populations. Analyzing anthropometric surveys of 232,684 children and adults from across 80 ethnolinguistic groups in sub-Saharan Africa, Asia and the Americas, we confirm that body surface-to-volume correlates with contemporary temperature at magnitudes found in more latitudinally diverse samples (Adj. R2 = 0.14-0.28). However, far more variation in body surface-to-volume is attributable to genetic population structure (Adj. R2 = 0.50-0.74). Moreover, genetic population structure accounts for nearly all of the observed relationship between contemporary temperature and body surface-to-volume among children and adults. Indeed, after controlling for population structure, contemporary temperature accounts for no more than 4% of the variance in body form in these groups. This effect of genetic affinity on body form is also independent of other ecological variables, such as dominant mode of subsistence and household wealth per capita. These findings suggest that the observed fit of human body surface-to-volume with current climate in this sample reflects relatively large effects of existing genetic population structure of contemporary humans compared to plastic response to current environments.

Introduction: Hypothalamic-pituitary-adrenal (HPA) axis activity is related to childhood disruptive behavior disorders and to exposure to abuse and neglect. This study explores the relationship of diurnal salivary cortisol levels with oppositional defiant disorder (ODD) and caregiver attitudes toward physical punishment among boys in Mongolia., Methods: Salivary cortisol was collected in the home or institution 4 times daily for 4 days from 46 boys, aged 4-10 years, in Ulaanbaatar, Mongolia. Caregivers rated child disruptive behavior symptoms, attitudes toward physical punishment, and community violence exposures. Mixed effects models were used to estimate the association of psychopathology and caregiver attitudes with salivary cortisol levels., Results: Boys meeting criteria for ODD displayed consistently lower diurnal salivary cortisol levels compared to boys without ODD diagnoses. Controlling for ODD diagnosis, boys with depression showed higher cortisol levels throughout the day. No other diagnosis was associated with cortisol levels. Psychiatric diagnosis accounted for 17% of between individual variations in cortisol levels unexplained by the covariates. In a separate model, caregivers' beliefs regarding physical punishment accounted for 11% of between individual differences: boys with caregivers who stated physical punishment was necessary for discipline displayed hypocortisolism. Institutionalization did not associate with cortisol levels., Discussion: Salivary cortisol data from a non-Western naturalistic setting support an association of reduced basal HPA activity with disruptive behavior disorders and caregiver attitudes toward discipline. These findings suggest HPA functioning may be a reflection of or mediate disruptive behavior disorders in children across ethnic and cultural settings., (© 2014 Wiley Publishing Asia Pty Ltd.)

Background: Concerted evolution is normally used to describe parallel changes at different sites in a genome, but it is also observed in languages where a specific phoneme changes to the same other phoneme in many words in the lexicon—a phenomenon known as regular sound change. We develop a general statistical model that can detect concerted changes in aligned sequence data and apply it to study regular sound changes in the Turkic language family., Results: Linguistic evolution, unlike the genetic substitutional process, is dominated by events of concerted evolutionary change. Our model identified more than 70 historical events of regular sound change that occurred throughout the evolution of the Turkic language family, while simultaneously inferring a dated phylogenetic tree. Including regular sound changes yielded an approximately 4-fold improvement in the characterization of linguistic change over a simpler model of sporadic change, improved phylogenetic inference, and returned more reliable and plausible dates for events on the phylogenies. The historical timings of the concerted changes closely follow a Poisson process model, and the sound transition networks derived from our model mirror linguistic expectations., Conclusions: We demonstrate that a model with no prior knowledge of complex concerted or regular changes can nevertheless infer the historical timings and genealogical placements of events of concerted change from the signals left in contemporary data. Our model can be applied wherever discrete elements—such as genes, words, cultural trends, technologies, or morphological traits—can change in parallel within an organism or other evolving group., (Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Validation studies of self-reported BMI are limited to populations in high-income countries or urban settings. Here, we assess the accuracy of two proxy measures of measured height, weight and BMI - self-reported values and the Stunkard figure scale - in a semi-rural population in Guatemala., Methods: Self-reported values and Stunkard figure selection were elicited prior to biometric measurements from a total of 175 non-pregnant women recruited based on a stratified random sample of households, with 92 women providing full data for validation across measures., Results: 86.3% of participants self-reported weight and 62.3% height. Among those responding, self-reported weight is highly accurate though lower relationships for height contribute to error in reported BMI. The Stunkard scale has a higher response rate (97.1%) and while less accurate in predicting BMI values, more accurately predicts BMI categories., Conclusions: Self-reported measures are more accurate than the Stunkard scale in estimating BMI values, while the latter is more accurate in estimating BMI categories. High non-response rates and lower correlations between reported and measured height caution against using self-reported biometric data other than raw weight in low-resource settings.

Many studies have linked measures of adult body shape and mass in ancient and contemporary populations to ecogeographical variables such as temperature and latitude. These results tend to support Bergmann's rule, which posits that bodies will be relatively less slender for their height in colder climates and more slender in warmer climates. Less well explored is the ontogeny of these population-level differences. Here we use data on infants and children from 46 low and lower income countries to test whether children's weight for height is associated with measures of temperature and latitude. We also test the hypothesis that children living in areas with greater pathogen prevalence will be lighter for their height because of life history trade-offs between investment in immune function and growth. Finally, we test whether population specific adult body mass predicts infant and child body mass, and whether this is independent of ecogeographical variables. Our results show that maximum monthly temperature explains 17% of children's weight for height while adult population-level body mass explains ∼44% (Table ). The measures of pathogen prevalence explain little of the variation in children's body shape (8%; P > 0.05). Our results suggest that population differences are consistent with Bergmann's rule but parental body shape explains more variance. Moreover, these population-level differences arise early in development, suggesting that any possible environmental influences occur in utero and/or result from epigenetic or population genetic differences., (Copyright © 2014 Wiley Periodicals, Inc.)

Measures of human body mass confound 1) well-established population differences in body form and 2) exposure to obesogenic environments, posing challenges for using body mass index (BMI) in cross-population studies of body form, energy reserves, and obesity-linked disease risk. We propose a method for decomposing population BMI by estimating basal BMI (bBMI) among young adults living in extremely poor, rural households where excess body mass accumulation is uncommon. We test this method with nationally representative, cross-sectional Demographic and Health Surveys (DHS) collected from 69,916 rural women (20-24 years) in 47 low-income countries. Predicting BMI by household wealth, we estimate country-level bBMI as the average BMI of young women (20-24 years) living in rural households with total assets <400 USD per capita. Above 400 USD per capita, BMI increases with both wealth and age. Below this point, BMI hits a baseline floor showing little effect of either age or wealth. Between-country variation in bBMI (range of 4.3 kg m(-2) ) is reliable across decades and age groups (R(2)  = 0.83-0.88). Country-level estimates of bBMI show no relation to diabetes prevalence or country-level GDP (R(2)  < 0.05), supporting its independence from excess body mass. Residual BMI (average BMI minus bBMI) shows better fit with both country-level GDP (R(2)  = 0.55 vs. 0.40) and diabetes prevalence (R(2)  = 0.23 vs. 0.17) than does conventional BMI. This method produces reliable estimates of bBMI across a wide range of nationally representative samples, providing a new approach to investigating population variation in body mass., (Copyright © 2013 Wiley Periodicals, Inc.)

Human populations differ reliably in the degree to which people favor family, friends, and community members over strangers and outsiders. In the last decade, researchers have begun to propose several economic and evolutionary hypotheses for these cross-population differences in parochialism. In this paper, we outline major current theories and review recent attempts to test them. We also discuss the key methodological challenges in assessing these diverse economic and evolutionary theories for cross-population differences in parochialism.

This paper proposes a benchmark for comparing SES gradients across countries, based on gross domestic product apportioned to members of differing wealth categories within countries. Using this approach, we estimate absolute wealth in 360 populations in 36 developing countries and model its relationship with overweight (BMI≥25) among non-pregnant women ages 18-49. A simple model based on absolute wealth alone strongly predicts odds of overweight (R(2)=0.59), a relationship that holds both between countries and between different groups in the same country (10 populations for each of 36 countries). Moreover, world region modifies this relationship, accounting for an additional 22% of variance (R(2)=0.81). This allows us to extract a basic pattern: rising rates of overweight in lower and middle income countries closely track increasing economic resources, and the shape of that gradient differs by region in systematic ways., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Much research has established reliable cross-population differences in motivations to invest in one's in-group. We compare two current historical-evolutionary hypotheses for this variation based on (1) effective large-scale institutions and (2) pathogen threats by analyzing cross-national differences (N = 122) in in-group preferences measured in three ways. We find that the effectiveness of government institutions correlates with favoring in-group members, even when controlling for pathogen stress and world region, assessing reverse causality, and providing a check on endogeneity with an instrumental variable analysis. Conversely, pathogen stress shows inconsistent associations with in-group favoritism when controlling for government effectiveness. Moreover, pathogen stress shows little to no association with in-group favoritism within major world regions whereas government effectiveness does. These results suggest that variation in in-group preferences across contemporary nation-states is more consistent with a generalized response to institutions that meet basic needs rather than an evolved response dedicated to pathogens.

The study of human variation in adiposity and lean mass is important for understanding core processes in human evolution, and is increasingly a public health concern as the "obesity epidemic" expands globally. The dominant measure of population differences in adiposity is Body Mass Index (BMI), which suffers from systematic biases across populations due to variation in the relationship between true body fat, height and weight. Here we develop simplified corrections for such anthropometric-based measures of adiposity that can take into account this population variation. These corrections derive from a recent model proposed by Burton that assumes humans accrue mass in two ways-growth in height that adds bone and muscle, and growth in body fat and the ancillary fat-free mass (FFM) needed to support this additional body fat. We analyze two ethnically diverse datasets with dual X-ray absorptiometry-measured (DXA) fat mass, assessing the fit of Burton's model and deriving novel corrections based on estimated musculoskeletal slenderness. The resulting model provides excellent fit to fat mass within populations (average R2 = 0.92 for women and R2 = 0.83 for men). World populations differ dramatically in musculoskeletal slenderness (up to a difference of 4.4 kg/m2), as do men and women (differences of 3.3-4.5 kg/m2), leading to clear population corrections. These findings point to a conceptually straightforward tool for estimating true differences in adiposity across populations, and suggest an alternative to BMI that provides a more accurate and theoretically based estimate of body fat than that traditionally derived from height and weight measures., (Copyright © 2013 Wiley Periodicals, Inc.)

Background: Post-conflict mental health studies in low-income countries have lacked pre-conflict data to evaluate changes in psychiatric morbidity resulting from political violence., Aims: This prospective study compares mental health before and after exposure to direct political violence during the People's War in Nepal., Method: An adult cohort completed the Beck Depression Inventory and Beck Anxiety Inventory in 2000 prior to conflict violence in their community and in 2007 after the war., Results: Of the original 316 participants, 298 (94%) participated in the post-conflict assessment. Depression increased from 30.9 to 40.6%. Anxiety increased from 26.2 to 47.7%. Post-conflict post-traumatic stress disorder (PTSD) was 14.1%. Controlling for ageing, the depression increase was not significant. The anxiety increase showed a dose-response association with conflict exposure when controlling for ageing and daily stressors. No demographic group displayed unique vulnerability or resilience to the effects of conflict exposure., Conclusions: Conflict exposure should be considered in the context of other types of psychiatric risk factors. Conflict exposure predicted increases in anxiety whereas socioeconomic factors and non-conflict stressful life events were the major predictors of depression. Research and interventions in post-conflict settings therefore should consider differential trajectories for depression v. anxiety and the importance of addressing chronic social problems ranging from poverty to gender and ethnic/caste discrimination.

In low income countries worldwide, rising standards of living have spurred an unprecedented rise in obesity. However, in numerous wealthy countries the trend frequently reverses with poorer and less educated women more likely to be overweight than their wealthier compatriots. One prominent explanation for this reverse gradient is that economic deprivation leads to food choices which paradoxically increase energy intake. If true, this would challenge current evolutionary accounts for the modern obesity epidemic and have serious implications for how policy makers tackle increasing obesity in the US and worldwide. In this article, we critically review the hypothesis that deprivation leads people to choose cheaper foods which in turn foster overconsumption of energy. Though the hypothesis is consistent with numerous cross-sectional studies, available longitudinal studies from high-, middle-, and low-income countries show the reverse-that when populations experience resource declines, they experience either declines in BMI or decelerations in BMI growth. Most notably, the recent recession in the US coincides with a clear deceleration in women's obesity across income groups. We conclude by briefly reviewing other plausible explanations for the reverse gradient among women in developing countries. Finally, we discuss how theoretical perspectives and comparative, historical approaches from human biology are useful tools for examining the current wealth of hypotheses about obesity in population health., (Copyright © 2012 Wiley Periodicals, Inc.)

Objectives: We aimed to test the hypothesized role of shared body size norms in the social contagion of body size and obesity., Methods: Using data collected in 2009 from 101 women and 812 of their social ties in Phoenix, Arizona, we assessed the indirect effect of social norms on shared body mass index (BMI) measured in 3 different ways., Results: We confirmed Christakis and Fowler's basic finding that BMI and obesity do indeed cluster socially, but we found that body size norms accounted for only a small portion of this effect (at most 20%) and only via 1 of the 3 pathways., Conclusions: If shared social norms play only a minor role in the social contagion of obesity, interventions targeted at changing ideas about appropriate BMIs or body sizes may be less useful than those working more directly with behaviors, for example, by changing eating habits or transforming opportunities for and constraints on dietary intake.

Obesity is understood as a major medical and public health challenge, but the stigma attached to it also creates extraordinary suffering. The pervasiveness of morally negative views toward the overweight and obese, such as laziness and lack of self-control, are undeniable in mainstream U.S. society, situated both institutionally (such as health care barriers or media stereotypes) and interpersonally (such as the negative comments of others). To test basic pathways related to the etiology of women's vulnerability to feeling "fat-stigma" in interpersonal relationships, we present a study conducted between August and November 2009 that combines social network, anthropometric, body image, and interview data for 112 women aged 18-45 years, living in Phoenix, Arizona, U.S., and linked follow-up interviews with 823 of their social ties. Based on the proposition that some social network characteristics should amplify the personal experience of stigma, and others should ameliorate it, we ask: what relationship qualities make women more sensitive to the judgments of others about their weight? We find that what others say about women has only a very limited influence on how women judge others' negative views of their weight once actual body size is taken into account, but that women are more influenced by the opinions of those they are closer to and interact with more often. Ultimately, the degree to which women perceive themselves to be judged by others regarding their weight is not well explained by the actual opinions of people in their networks, either known or unknown to them. The assumption that social network norms exert considerable influence on people's stigma experiences needs to be carefully evaluated, at least in the domain of overweight and obesity., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

In the aftermath of a decade-long Maoist civil war in Nepal and the recent relocation of thousands of Bhutanese refugees from Nepal to Western countries, there has been rapid growth of mental health and psychosocial support programs, including posttraumatic stress disorder treatment, for Nepalis and ethnic Nepali Bhutanese. This medical anthropology study describes the process of identifying Nepali idioms of distress and local ethnopsychology and ethnophysiology models that promote effective communication about psychological trauma in a manner that minimizes stigma for service users. Psychological trauma is shown to be a multifaceted concept that has no single linguistic corollary in the Nepali study population. Respondents articulated different categories of psychological trauma idioms in relation to impact on the heart-mind, brain-mind, body, spirit, and social status, with differences in perceived types of traumatic events, symptom sets, emotion clusters and vulnerability. Trauma survivors felt blamed for experiencing negative events, which were seen as karma transmitting past life sins or family member sins into personal loss. Some families were reluctant to seek care for psychological trauma because of the stigma of revealing this bad karma. In addition, idioms related to brain-mind dysfunction contributed to stigma, while heart-mind distress was a socially acceptable reason for seeking treatment. Different categories of trauma idioms support the need for multidisciplinary treatment with multiple points of service entry.

Studies of language change have begun to contribute to answering several pressing questions in cognitive sciences, including the origins of human language capacity, the social construction of cognition and the mechanisms underlying culture change in general. Here, we describe recent advances within a new emerging framework for the study of language change, one that models such change as an evolutionary process among competing linguistic variants. We argue that a crucial and unifying element of this framework is the use of probabilistic, data-driven models both to infer change and to compare competing claims about social and cognitive influences on language change.

In the last two decades, culture has emerged in population health as a common explanation for health outcomes and disparities. This paper systematically reviews such cultural accounts, focusing on a historical sample of articles from prominent population health journals (1930-2008, n=100) and a contemporary sample of articles in the American Journal of Public Health (2008, n=95). The review reveals that references to culture rarely (1) specify the precise pathways by which culture influences health or (2) assess the plausibility of these pathways. Despite these weaknesses, a few studies have begun to clarify, measure, and assess how culture can influence health outcomes, and these articles reflect promising new avenues for understanding how cultural factors influence variation in health and well-being.

Culture frequently is used to explain population differences in health. This glossary defines key concepts and terms relevant to the concept of culture and describes three challenges--definitional, theoretical, and methodological--in identifying specific pathways by which culture affects health.

The evolution of cooperation is a central problem in biology and the social sciences. While theoretical work using the iterated prisoner's dilemma (IPD) has shown that cooperation among non-kin can be sustained among reciprocal strategies (i.e. tit-for-tat), these results are sensitive to errors in strategy execution, cyclical invasions by free riders, and the specific ecology of strategies. Moreover, the IPD assumes that a strategy's probability of playing the PD game with other individuals is independent of the decisions made by others. Here, we remove the assumption of independent pairing by studying a more plausible cooperative dilemma in which players can preferentially interact with a limited set of known partners and also deploy longer-term accounting strategies that can counteract the effects of random errors. We show that cooperative strategies readily emerge and persist in a range of noisy environments, with successful cooperative strategies (henceforth, cliquers) maintaining medium-term memories for partners and low thresholds for acceptable cooperation (i.e. forgiveness). The success of these strategies relies on their cliquishness-a propensity to defect with strangers if they already have an adequate number of partners. Notably, this combination of medium-term accounting, forgiveness, and cliquishness fits with empirical studies of friendship and other long-term relationships among humans.

Cortisol measures often are used to examine variation in hypothalamic-pituitary-adrenal axis (HPA) activity as well as broader patterns of differential health. However, substantial within-individual variation renders single cortisol measurements unreliable as estimates for probing differences between individuals and groups. A standard practice to clarify between-individual differences involves collecting multiple samples from each participant and then deriving person-specific averages. By ignoring information about variation at between- and within-individual levels, this technique impedes cross-study comparison of results, ignores data useful for future study design, and hinders the analysis of cross-level interactions. This report describes how multilevel approaches can simultaneously model between- and within-individual variation in diurnal cortisol levels without using crude averages. We apply these models to data from children in Nepal (n=29, 11-15 samples per child), Mongolia (n=47, 8-12 samples per child) and the US (n=1269, 1-6 samples per child). Using the Nepal data, we show how an analysis of crude time-adjusted aggregates does not detect an association between aggressive behavior and cortisol levels, while a multilevel analysis does. More importantly, we argue that the 'roadmap' to variation generated by these multilevel models provides meaningful information about the predictive accuracy--not just statistical significance--of relationships between cortisol levels and individual-level variables, such as psychopathology, age, and gender. The 'roadmap' also facilitates comparison between the results from different studies and estimation of the necessary number of cortisol measurements for future investigations.

This study discusses quality of life in post-socialist Mongolia. Yadargaa, a fatigue-related illness in traditional Mongolian medicine, results from lifestyle imbalance. We examine the distribution of yadargaa and its association to socioeconomic changes under capitalism. Ethnographic interviews concerning yadargaa were conducted with health professionals, yadargaa patients, and laypersons. Epidemiological methods were used to identify risk groups, to estimate the point prevalence, and to assess the distribution of meanings and interpretations of yadargaa. The epidemiological sample included 194 individuals, half urban and half rural. Nearly half of the epidemiological sample suffered from yadargaa (49%). These yadargaa sufferers felt that they benefited less than non-yadargaa subjects from the current socioeconomic changes. Among these, perceived change in employment opportunities was one of the best predictors of yadargaa. Additionally, yadargaa sufferers were predominantly women, the elderly, and urban residents. Yadargaa varies greatly in presentation; Western psychiatric categories are only able to explain half of yadargaa cases. In conclusion, yadargaa strongly associates with disenfranchised groups in the capitalist economy. As a culturally constructed indicator of quality of life, yadargaa is a window into the lives of women and men in post-socialist Mongolia.

Mothers of infants (n = 328) born between 1996 and 1999 in four Guatemalan communities were interviewed every 2 wk until 6 mo postpartum (pp) to collect prospective breast-feeding data and assess the association between delayed (>3 d pp) onset of lactation (OL) and the risk of ending full breast-feeding. Cox proportional hazards regression was used to examine the association between delayed OL and the hazard of ending full breast-feeding in the first 6 mo, adjusted for potential confounders and effect modifiers. A significant interaction with community was found (community-specific hazard ratios: HR(A) = 2.87, 95% CI = 1.25, 6.60; HR(B) = 3.43, 95% CI = 1.55, 7.59; HR(C) = 0.26, 95% CI = 0.06, 1.14; HR(D) = 1.11, 95% CI = 0.44, 2.77). Supplementation before OL (preonset supplementation) was associated with delayed OL [odds ratio (OR) = 4.87, 95% CI = 2.29, 10.36] and an increased risk of ending full breast-feeding (HR = 1.49, 95% CI = 1.05, 2.11). In the two communities in which mothers who experienced delayed OL had a significantly greater risk of ending full breast-feeding than did mothers experiencing normal OL, the association between delayed OL and full breast-feeding was mediated in part by preonset supplementation. Further analyses suggest that this was due to delayed OL leading to nonbreast milk feeds, rather than to introduction of supplements delaying OL. We conclude that some mothers who experience delayed OL are less likely to continue full breast-feeding in the first 6 mo and that further research should examine the contextual factors that modify this relationship.