Parental hormones are associated with crop loss and family sickness following catastrophic flooding in lowland Bolivia

When the flood passes, does health return? A short panel examining water and food insecurity, nutrition, and disease after an extreme flood in lowland Bolivia

OBJECTIVES

Flooding is the most frequent extreme-weather disaster and disproportionately burdens marginalized populations. This article examines how food and water insecurity, blood pressure (BP), nutritional status, and diarrheal and respiratory illnesses changed during the 2 months following a historic flood in lowland Bolivia.

METHODS

Drawing on longitudinal data from Tsimane' forager-horticulturalist (n = 118 household heads; n = 129 children) directly after a historic 2014 flood and ~2 months later, we use fixed effects linear regression and random effects logistic regression models to test changes in the markers of well-being and health over the recovery process.

RESULTS

Results demonstrated that water insecurity scores decreased significantly 2 month's postflood, while food insecurity scores remained high. Adults' systolic and diastolic BP significantly declined 2 months after the flood's conclusion. Adults experienced losses in measures of adiposity (BMI, sum of four skinfolds, waist circumference). Children gained weight and BMI-for-age Z-scores indicating buffering of children by adults from food stress that mainly occurred in the community closer to the main market town with greater access to food aid. Odds of diarrhea showed a nonsignificant decline, while cough increased significantly for both children and adults 2 months postflood.

CONCLUSIONS

Water insecurity and BP improved during the recovery process, while high levels of food insecurity persisted, and nutritional stress and respiratory illness worsened. Not all indicators of well-being and health recover at the same rate after historic flooding events. Planning for multiphase recovery is critical to improve health of marginalized populations after flooding.

Household Food Insecurity, Hair Cortisol, and Adiposity Among Tsimane' Hunter-Forager-Horticulturalists in Bolivia

OBJECTIVES

This study examined how household food insecurity (HFI) and chronic stress relate to adiposity among Tsimane' hunter-forager-horticulturalists in remote Bolivia with limited access to energy-dense processed foods that promote weight gain among industrialized populations.

METHODS

Retrospective cross-sectional data on HFI (via the Household Food Insecurity Access Scale [HFIAS]), hair cortisol concentration (HCC), adiposity (BMI, body fat percentage [%BF]), and sociodemographics were collected from 171 men, 164 women, and 167 children. Linear mixed-effects models tested linear, quadratic, joint, and interactive relationships between adiposity measures and both the HFIAS score and HCC.

RESULTS

Among children, each 3-point HFIAS score increase was associated with a 0.44-point higher %BF (SE = 0.22, P = 0.04). However, each 20% increase in HCC was associated with a -0.29-point difference in %BF (SE = 0.12, P = 0.01). Among men, a slight curvilinear relationship emerged between HFIAS and BMI. HFIAS and HCC were unrelated to adiposity measures among women. HCC did not modify relationships between HFIAS and adiposity in any subgroup.

CONCLUSIONS

These findings from a remote, small-scale population suggest that positive associations between HFI and adiposity are not isolated to contexts of industrialized food environments and heavy reliance on processed foods. However, these dynamics and the role of stress appear to differ by sex and age group.

Do wealth and inequality associate with health in a small-scale subsistence society?

In high-income countries, one’s relative socio-economic position and economic inequality may affect health and well-being, arguably via psychosocial stress. We tested this in a small-scale subsistence society, the Tsimane, by associating relative household wealth (n = 871) and community-level wealth inequality (n = 40, Gini = 0.15–0.53) with a range of psychological variables, stressors, and health outcomes (depressive symptoms [n = 670], social conflicts [n = 401], non-social problems [n = 398], social support [n = 399], cortisol [n = 811], body mass index [n = 9,926], blood pressure [n = 3,195], self-rated health [n = 2523], morbidities [n = 1542]) controlling for community-average wealth, age, sex, household size, community size, and distance to markets. Wealthier people largely had better outcomes while inequality associated with more respiratory disease, a leading cause of mortality. Greater inequality and lower wealth were associated with higher blood pressure. Psychosocial factors did not mediate wealth-health associations. Thus, relative socio-economic position and inequality may affect health across diverse societies, though this is likely exacerbated in high-income countries.

Poverty is bad for health. People living in poverty are more likely to struggle to afford nutritious food, lack access to health care, or be overworked or stressed. This may make them susceptible to chronic diseases, contribute to faster aging, and shorten their lifespans. In high-income countries, there is growing evidence to suggest that a person’s ‘rank’ in society also impacts their health. For example, individuals who have a lower position in the social hierarchy report worse health outcomes, regardless of their incomes. But it is unclear why living in an unequal society or having a lower social status contributes to poorer health.

One possibility is that inequalities in society are creating a stressful environment that leads to worse physical and mental outcomes. It is thought that this stress largely comes from how humans evolved to prioritize reaching a higher social status over having a long and healthy life. If this is the case, this would mean that the link between social status and health would also be present in non-industrialized communities where social hierarchies tend to be less pronounced.

To test this, Jaeggi, Blackwell et al. studied the Indigenous Tsimane population in Bolivia who live in small communities and forage and farm their own food. The income and relative wealth of 870 households from 40 Tsimane communities were compared against various outcomes, including symptoms associated with depression, stress hormone levels, blood pressure, self-rated health and several diseases.

Jaeggi, Blackwell et al. found poverty and inequality did not negatively impact all of the health outcomes measured as has been previously reported for industrialized societies. However, blood pressure was higher among people with lower incomes or those who lived in more unequal communities. But because the Tsimane people generally have low blood pressure, the differences were too small to have much effect on their health. People who lived in more unequal communities were also three times more likely to have respiratory infections, but the reason for this was unclear.

This shows that social determinants such as a person’s wealth or inequality can affect health, even in communities with less rigid social hierarchies. In industrial societies the effect may be worse in part because they are compounded by lifestyle factors, such as diets rich in fat and sugar, and physical inactivity which can also increase blood pressure. This information may help policy makers reduce health disparities by addressing some of the social determinants of health and the lifestyle factors that cause them.

Sharing and caring: Testosterone, fathering, and generosity among BaYaka foragers of the Congo Basin

Humans are rare among mammals in exhibiting paternal care and the capacity for broad hyper-cooperation, which were likely critical to the evolutionary emergence of human life history. In humans and other species, testosterone is often a mediator of life history trade-offs between mating/competition and parenting. There is also evidence that lower testosterone men may often engage in greater prosocial behavior compared to higher testosterone men. Given the evolutionary importance of paternal care and heightened cooperation to human life history, human fathers' testosterone may be linked to these two behavioral domains, but they have not been studied together. We conducted research among highly egalitarian Congolese BaYaka foragers and compared them with their more hierarchical Bondongo fisher-farmer neighbors. Testing whether BaYaka men's testosterone was linked to locally-valued fathering roles, we found that fathers who were seen as better community sharers had lower testosterone than less generous men. BaYaka fathers who were better providers also tended to have lower testosterone. In both BaYaka and Bondongo communities, men in marriages with greater conflict had higher testosterone. The current findings from BaYaka fathers point to testosterone as a psychobiological correlate of cooperative behavior under ecological conditions with evolutionarily-relevant features in which mutual aid and sharing of resources help ensure survival and community health.

Relationship of sanitation, water boiling, and mosquito nets to health biomarkers in a rural subsistence population

OBJECTIVES

Throughout human evolutionary history, parasites and pathogens were a major cause of mortality-modern urban life with public health infrastructure has changed disease exposure. We examine associations between boiling water, using latrines, mosquito net usage, and biomarkers among the Tsimane, a nonindustrial subsistence population with little public health infrastructure.

METHODS

We conducted cross sectional surveys on water, latrines, and bed nets among 507 heads of households (aged 18-92 years, median age 41 years). Regression models estimated associations between behaviors and health biomarkers (ie, white blood cell count [WBC], hemoglobin, eosinophil count, and erythrocyte sedimentation rate) adjusting for age, sex, body mass index, wealth, schooling, and distance to the nearby market town.

RESULTS

Latrine use is associated with 6.5% lower WBC count (β = -679.6, P = .031, SE = 314.1), 17.4% lower eosinophil counts (β = -244.7, P = .023, SE = 107.2), and reduced odds of eosinophilia (adjusted OR = 0.40, P < .019, 95% CI = 0.18-0.86). Boiling water and mosquito net use are not significantly associated with any biomarkers measured.

CONCLUSIONS

In a subsistence population currently undergoing epidemiological transition, we find that latrine use was associated with several objective measures of health. This suggests that relatively low cost and low maintenance public health interventions may wish to focus on latrine use, as there is unmet need and potential health benefits for those who use latrines. Additionally, while the cost is higher, public health organizations aimed at improving sanitation may be able to use minimally invasive field-collected biomarkers as a diagnostic to objectively test the efficacy of interventions with greater specificity than anthropometric measurements.

With a little help from her friends (and family) part II: Non-maternal caregiving behavior and physiology in mammals

The diversity of competing frameworks for explaining the evolution of non-maternal care in mammals (Part I, this issue) reflects the vast range of behaviors and associated outcomes these theories attempt to subsume. Caretaking comprises a wide variety of behavioral domains, and is mediated by an equally large range of physiological systems. In Part II, we provide an overview of how non-maternal care in mammals is expressed, the ways in which it is regulated, and the many effects such care has on both recipients and caretakers. We also discuss the two primary ways in which closer integration of ultimate and proximate levels of explanation can be useful when addressing questions about non-maternal caretaking. Specifically, proximate mechanisms provide important functional clues, and are key to testing theory concerning evolutionary tradeoffs. Finally, we highlight a number of methodological and publication biases that currently shape the literature, which provide opportunities for knowledge advancement in this domain going forward. In this conclusion to our two-part introduction, we provide a broad survey of the behavior and physiology that the contributions to this special issue represent.

Nutrition transition in 2 lowland Bolivian subsistence populations

Background

Traditional diets are often credited for the robust cardiometabolic health of subsistence populations. Yet, rural subsistence populations are undergoing nutrition transitions that have been linked to the increase in chronic noncommunicable diseases. Few studies have presented detailed dietary estimates in transitioning populations.

Objectives

We aimed to 1) characterize and compare dietary profiles of 2 neighboring subsistence populations in Bolivia who vary in market integration and 2) identify dietary factors contributing to low cardiovascular disease risk.

Design

We used a mixed longitudinal design to estimate nutrient intake via 24-h recall and dietary questionnaires among 1299 Tsimane (aged 30-91 y) and 229 Moseten (aged 30-84 y) men and women. We constructed population-level estimates of energy intake, dietary diversity, and nutrient shortfalls and analyzed dietary changes over time and space using multilevel models. Last, we compared Tsimane and Moseten dietary profiles with those of Americans (NHANES).

Results

The Tsimane diet was characterized by high energy (2422-2736 kcal/d), carbohydrate (376-423 g/d), and protein (119-139 g/d) intakes; low fat intake (40-46 g/d); and low dietary diversity relative to the average US diet. Most calories (64%) were derived from complex carbohydrates. Total energy and carbohydrate intake increased significantly during the 5-y study, particularly in villages near market towns. Tsimane consumption of food additives (lard, oil, sugar, salt) increased significantly [sugar (15.8 g ⋅ person-1 ⋅ d-1) and oil (4.9 mL ⋅ person-1 ⋅ d-1)] between 2010 and 2015. The more-acculturated Moseten consumed substantially more sugar (by 343%) and oil (by 535%) than the Tsimane.

Conclusions

A high-energy diet rich in complex carbohydrates is associated with low cardiovascular disease risk when coupled with a physically active lifestyle. A transition away from a high-fiber and low-fat, low-salt, and low-processed-sugar diet is a salient health risk for transitioning populations. Evidence of a nutrition transition in Bolivia parallels trends of increasing body fat and body mass index, which suggests that a low prevalence of cardiovascular disease may not persist.