Adipose development is consistent across hunter-gatherers and diverges from western references.

Despite agreement that humans have evolved to be unusually fat primates, adipose patterning among hunter-gatherers has received little empirical consideration. Here we consider the development of adiposity among four contemporary groups of hunter-gatherers, the Aka, Savanna Pumé, Ju'/Hoansi and Agta using multi-level generalized additive mixed modelling to characterize the growth of tricep skinfolds from early childhood through adolescence. In contrast to references, hunter-gatherers show several consistent patterns: (i) children are lean with little fat accumulation; (ii) no adiposity rebound at 5 years is evident; (iii) girls on average have built 90% of their body size, and reach menarche when adiposity is at its maximum velocity; and (iv) a metabolic trade-off is evident in young, but not older children, such that both boys and girls prioritize skeletal growth during middle childhood, a trade-off that diminishes during adolescence when height velocity increases in pace with fat accumulation.

Uncertainty in a globalizing world. Livelihood and fertility variance increases in response to rapid change.

Objectives: The extreme condition that we address in this special issue is how people adapt to rapid change, which in this case study is instigated by globalization and the process of market integration. Although market integration has been underway for centuries in some parts of the world, it often occurs precipitously in small-scale societies, initiating an abrupt break with traditional ways of life and fostering a keen sense of uncertainty.

Methods: Using cross sections from 30-years of data collected in a Yucatec Maya subsistence farming community, we test the expectation that when payoffs to pursue new livelihood and reproductive options are uncertain, variance in social, economic, and reproductive traits will increase in the population.

Kin networks and opportunities for reproductive cooperation and conflict among hunter-gatherers.

Little is known about the potential for reproductive conflict among hunter-gatherer populations, who are characterized by bilateral kinship ties, flexible residential mobility, and high offspring mortality. To assess the potential for reproductive conflict, we use longitudinal residence and reproductive history data for two bands of South American foragers. Using multilevel logistic regressions ( = 44 women, = 712 person years), we examine how yearly measures of (i) camp composition, (ii) distribution of female kin and (iii) a woman's position in a female kinship network impact the likelihood of giving birth or experiencing a child's death.

Sex differences in adipose development in a hunter-gatherer population.

Objective: Humans are unusually sexually dimorphic in body composition, with adult females having on average nearly twice the fat mass as males. The development of adipose sex differences has been well characterized for children growing up in food-abundant environments, with less known about cross-cultural variation, particularly in populations without exposure to market foods, mechanized technologies, schooling, vaccination, or other medical interventions.

Methods: To add to the existing cross-cultural data, we fit multiple growth curves to body composition and anthropometric data to describe adipose development for the Savanna Pumé, South American hunter-gatherers.

Food insecurity, morbidity, and : Factors associated with depression severity in Guatemala measured with the Personal Health Questionnaire 9.

Background: Depression is the largest contributor to non-fatal health loss globally and the majority of this burden occurs in low- and middle-income countries. Yet, estimates of prevalence rates and severity in these contexts may be uncertain due to limited screening, lack of mental health providers, and stigma around mental disorders which may prevent individuals from seeking care. In Guatemala, estimates of depression vary, due in part to the range of screening and diagnostic instruments used and diversity of sample populations.

Body norms and normative bodies in Highland Guatemala.

Objectives: The concept of bionormalcy highlights the potential tensions between bodies defined clinically as normal or healthy, bodies that are normative (frequent) within a population, and bodies defined within a given social context as abnormal or devalued. Theories of resource scarcity predict preferences for larger bodies should deviate from what is biologically normative (i.e.

Balancing fertility and livelihood diversity in mixed economies.

Mixed economies provide a unique context for testing theories of fertility change. Because they have a stake in two traditions, mixed-economy households balance the demands of both a labor-based subsistence economy, which benefits from a large family, and a wage-labor economy, which benefits from reduced fertility. Additionally, household size changes over the course of its life-cycle and shapes available economic opportunities.

Disentangling wealth effects on fertility in 64 low- and middle-income countries.

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.

Scaling climate change to human behavior predicting good and bad years for Maya farmers.

Objectives: Human responses to climate variation have a rich anthropological history. However, much less is known about how people living in small-scale societies perceive climate change, and what climate data are useful in predicting food production at a scale that affects daily lives.

Methods: We use longitudinal ethnographic interviews and economic data to first ask what aspects of climate variation affect the agricultural cycle and food production for Yucatec Maya farmers.

Disentangling basal and accrued height-for-age for cross-population comparisons.

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.

Generalizability is not optional: insights from a cross-cultural study of social discounting.

Current scientific reforms focus more on solutions to the problem of reliability (e.g. direct replications) than generalizability.

Identifying the limits to socioeconomic influences on human growth.

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.

Learning from failures of protocol in cross-cultural research.

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.

Reproductive preferences during middle childhood and early adolescence in Guatemala.

Reproductive preferences and the spread of low fertility norms occupy a key position in debates regarding the causal mechanisms underlying sustained fertility declines. Most of the literature on reproductive preferences focuses on stability and variability of adult fertility preferences, and their relationship with behavioural outcomes. Little work has focused on the developmental origins of these preferences, particularly in populations undergoing rapid social and demographic change.

Worldwide fertility declines do not rely on stopping at ideal parities.

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).

Material wealth in 3D: Mapping multiple paths to prosperity in low- and middle- income countries.

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.

Revisiting Psychological Mechanisms in the Anthropology of Altruism.

Anthropologists have long been interested in the reasons humans choose to help some individuals and not others. Early research considered psychological mediators, such as feelings of cohesion or closeness, but more recent work, largely in the tradition of human behavioral ecology, shifted attention away from psychological measures to clearer observables, such as past behavior, genetic relatedness, affinal ties, and geographic proximity. In this paper, we assess the value of reintegrating psychological measures-perceived social closeness-into the anthropological study of altruism.

Weight-related stigma is a significant psychosocial stressor in developing countries: Evidence from Guatemala.

Weight-related stigma is established as a major psychosocial stressor and correlate of depression among people living with obesity in high-income countries. Anti-fat beliefs are rapidly globalizing. The goal of the study is to (1) examine how weight-related stigma, enacted as teasing, is evident among women from a lower-income country and (2) test if such weight-related stigma contributes to depressive symptoms.