Biological and Physical Anthropology Commons^™

Natural Selection Of Immune And Metabolic Genes Associated With Health In Two Lowland Bolivian Populations, Amanda J. Lea, Angela Garcia, Jesusa Arevalo, Julien F. Ayroles, Kenneth Buetow, Steve W. Cole, Daniel Eid Rodriguez, Maguin Gutierrez, Heather M. Highland, Paul L. Hooper, Anne Justice, Thomas Kraft, Kari E. North, Jonathan Stieglitz, Hillard Kaplan, Benjamin C. Trumble, Michael Gurven

ESI Publications

A growing body of work has addressed human adaptations to diverse environments using genomic data, but few studies have connected putatively selected alleles to phenotypes, much less among underrepresented populations such as Amerindians. Studies of natural selection and genotype–phenotype relationships in underrepresented populations hold potential to uncover previously undescribed loci underlying evolutionarily and biomedically relevant traits. Here, we worked with the Tsimane and the Moseten, two Amerindian populations inhabiting the Bolivian lowlands. We focused most intensively on the Tsimane, because long-term anthropological work with this group has shown that they have a high burden of both macro and microparasites, as …

Prevalence Of Dementia And Mild Cognitive Impairment In Indigenous Bolivian Forager-Horticulturalists, Margaret Gatz, Wendy J. Mack, Helena C. Chui, E. Meng Law, Giuseppe Barisano, M. Linda Sutherland, James D. Sutherland, Daniel Eid Rodriguez, Raul Quispe Gutierrez, Juan Copajira Adrian, Jesus Bani Cuata, Amy R. Borenstein, Ellen E. Waters, Andrei Irimia, Christopher J. Rowan, L. Samuel Wann, Adel H. Allam, Randall C. Thompson, Michael I. Miyamoto, David E. Michalik, Daniel K. Cummings, Edmond Seabright, Angela R. Garcia, Paul L. Hooper, Thomas S. Kraft, Caleb E. Finch, Gregory S. Thomas, Jonathan Stieglitz, Benjamin C. Trumble, Michael D. Gurven, Hillard Kaplan

ESI Publications

Introduction

We evaluated the prevalence of dementia and mild cognitive impairment (MCI) in indigenous Tsimane and Moseten, who lead a subsistence lifestyle.

Methods

Participants from population-based samples ≥ 60 years of age (n = 623) were assessed using adapted versions of the Modified Mini-Mental State Examination, informant interview, longitudinal cognitive testing and brain computed tomography (CT) scans.

Results

Tsimane exhibited five cases of dementia (among n = 435; crude prevalence = 1.2%, 95% confidence interval [CI]: 0.4, 2.7); Moseten exhibited one case (among n = 169; crude prevalence = 0.6%, 95% CI: 0.0, 3.2), all age ≥ 80 years. …

Marital Violence And Fertility In A Relatively Egalitarian High-Fertility Population, Jonathan Stieglitz, Benjamin C. Trumble, Hillard Kaplan, Michael Gurven

ESI Publications

Ultimate and proximate explanations of men’s physical intimate partner violence (IPV) against women have been proposed. An ultimate explanation posits that IPV is used to achieve a selfish fitness-relevant outcome, and predicts that IPV is associated with greater marital fertility. Proximate IPV explanations contain either complementary strategic components (for example, men’s desire for partner control), non-strategic components (for example, men’s self-regulatory failure), or both strategic and non-strategic components involving social learning. Consistent with an expectation from an ultimate IPV explanation, we find that IPV predicts greater marital fertility among Tsimané forager-horticulturalists of Bolivia (n = 133 marriages, 105 women). This …

Low Perceived Control Over Health Is Associated With Lower Treatment Uptake In A High Mortality Population Of Bolivian Forager-Farmers, Sarah Alami, Jonathan Stieglitz, Hillard Kaplan, Michael Gurven

ESI Publications

Indigenous people worldwide suffer from higher rates of morbidity and mortality than neighboring populations. In addition to having limited access to public health infrastructure, indigenous people may also have priorities and health perceptions that deter them from seeking adequate modern healthcare. Here we propose that living in a harsh and unpredictable environment reduces motivation to pursue deliberate, costly action to improve health outcomes. We assess whether variation in Health Locus of Control (HLC), a psychological construct designed to capture self-efficacy with respect to health, explains variation in treatment uptake behavior among Tsimane Amerindians (N=690; age range: 40–89 years; 55.8% female; …

Horticultural Activity Predicts Later Localized Limb Status In A Contemporary Pre-Industrial Population, Jonathan Stieglitz, Benjamin C. Trumble, Hillard Kaplan, Michael Gurven

ESI Publications

Objectives—Modern humans may have gracile skeletons due to low physical activity levels and mechanical loading. Tests using prehistoric skeletons are limited by the inability to assess behaviour directly, while modern industrialized societies possess few socio-ecological features typical of human evolutionary history. Among Tsimane forager-horticulturalists, we test whether greater activity levels and, thus, increased loading earlier in life are associated with greater later-life bone status and diminished age-related bone loss.

Materials and Methods—We used quantitative ultrasonography to assess radial and tibial status among adults aged 20+ years (mean±SD age=49±15; 52% female). We conducted systematic behavioural observations to assess earlier-life …

Cognitive Performance Across The Life Course Of Bolivian Forager-Farmers With Limited Schooling, Michael Gurven, Eric Fuerstenberg, Benjamin C. Trumble, Jonathan Stieglitz, Bret Beheim, Helen Davis, Hillard Kaplan

ESI Publications

Cognitive performance is characterized by at least two distinct life course trajectories. Many cognitive abilities (e.g. “effortful processing” abilities including fluid reasoning, and processing speed) improve throughout early adolescence and start declining in early adulthood, while other abilities (e.g. “crystallized” abilities like vocabulary breadth) improve throughout adult life, remaining robust even at late ages. Although schooling may impact performance and cognitive “reserve”, it has been argued that these age patterns of cognitive performance are human universals. Here we examine age patterns of cognitive performance among Tsimane forager-horticulturalists of Bolivia, and test whether schooling is related to differences in cognitive performance …

Growth References For Tsimane Forager-Horticulturalists Of The Bolivian Amazon, Aaron D. Blackwell, Samuel S. Urlacher, Bret Beheim, Christopher Von Rueden, Adrian V. Jaeggi, Jonathan Stieglitz, Benjamin C. Trumble, Michael Gurven, Hillard Kaplan

ESI Publications

Objectives—Growth standards and references currently used to assess population and individual health are derived primarily from urban populations, including few individuals from indigenous or subsistence groups. Given environmental and genetic differences, growth may vary in these populations. Thus, there is a need to assess whether international standards are appropriate for all populations, and to produce population specific references if growth differs. Here we present and assess growth references for the Tsimane, an indigenous population of Bolivian forager-horticulturalists.

Methods—Mixed cross-sectional/longitudinal anthropometrics (9,614 individuals; 30,118 observations; ages 0–29 years) were used to generate centile curves and Lambda-Mu-Sigma (LMS) tables for …

Associations Between Male Testosterone And Immune Function In A Pathogenically Stressed Forager-Horticultural Population, Benjamin C. Trumble, Aaron D. Blackwell, Jonathan Stieglitz, Melissa Emery Thompson, Ivan Maldonado Suarez, Hillard Kaplan, Michael Gurven

ESI Publications

Objectives—Despite well-known fitness advantages to males who produce and maintain high endogenous testosterone levels, such phenotypes may be costly if testosterone-mediated investment in reproductive effort trade-off against investment in somatic maintenance. Previous studies of androgen-mediated trade-offs in human immune function find mixed results, in part because most studies either focus on a few indicators of immunity, are confounded by phenotypic correlation, or are observational. Here the association between male endogenous testosterone and 13 circulating cytokines are examined before and after ex vivo antigen stimulation with phytohaemagglutinin (PHA) and lipopolysaccharides (LPS) in a high pathogen population of Bolivian forager-horticulturalists.

Materials …

High Resting Metabolic Rate Among Amazonian Forager-Horticulturalists Experiencing High Pathogen Burden, Michael Gurven, Benjamin C. Trumble, Jonathan Stieglitz, Gandhi Yetish, Daniel Cummings, Aaron D. Blackwell, Bret Beheim, Hillard Kaplan, Herman Pontzer

ESI Publications

Objectives—Resting metabolic rate (RMR) reflects energetic costs of homeostasis and accounts for 60-75% of total energy expenditure (TEE). Lean mass and physical activity account for much RMR variability, but the impact of prolonged immune activation from infection on human RMR is unclear in naturalistic settings. We evaluate the effects of infection on mass-corrected RMR among Bolivian forager-horticulturalists, and assess whether RMR declines more slowly with age than in hygienic sedentary populations, as might be expected if older adults experience high pathogen burden.

Materials and Methods—RMR was measured by indirect calorimetry (Fitmate MED, Cosmed) in 1,300 adults aged 20-90 …

Does Market Integration Buffer Risk, Erode Traditional Sharing Practices And Increase Inequality? A Test Among Bolivian Forager-Farmers, Michael Gurven, Adrian V. Jaeggi, Christopher Von Rueden, Paul L. Hooper, Hillard Kaplan

ESI Publications

Sharing and exchange are common practices for minimizing food insecurity in rural populations. The advent of markets and monetization in egalitarian indigenous populations presents an alternative means of managing risk, with the potential impact of eroding traditional networks. We test whether market involvement buffers several types of risk and reduces traditional sharing behavior among Tsimane Amerindians of the Bolivian Amazon. Results vary based on type of market integration and scale of analysis (household vs. village), consistent with the notion that local culture and ecology shape risk management strategies. Greater wealth and income were unassociated with the reliance on others for …

Depression As Sickness Behavior? A Test Of The Host Defense Hypothesis In A High Pathogen Population, Jonathan Stieglitz, Benjamin C. Trumble, Melissa Emery Thompson, Aaron D. Blackwell, Hillard Kaplan, Michael Gurven

ESI Publications

Sadness is an emotion universally recognized across cultures, suggesting it plays an important functional role in regulating human behavior. Numerous adaptive explanations of persistent sadness interfering with daily functioning (hereafter “depression”) have been proposed, but most do not explain frequent bidirectional associations between depression and greater immune activation. Here we test several predictions of the host defense hypothesis, which posits that depression is part of a broader coordinated evolved response to infection or tissue injury (i.e. “sickness behavior”) that promotes energy conservation and reallocation to facilitate immune activation. In a high pathogen population of lean and relatively egalitarian Bolivian foragerhorticulturalists, …

Low Mineral Density Of A Weight-Bearing Bone Among Adult Women In A High Fertility Population, Jonathan Stieglitz, Bret Beheim, Benjamin C. Trumble, Felicia C. Madimenos, Hillard Kaplan, Michael Gurven

ESI Publications

Evolutionary theories of aging posit that greater reproductive effort causes somatic decline given a fundamental trade-off between investing energy in reproduction and repair. Few studies in high fertility human populations support this hypothesis, and problems of phenotypic correlation can obscure the expected trade-off between reproduction and somatic condition. This cross-sectional study investigates whether greater reproductive effort is associated with reduced calcaneal bone mineral density (BMD) among female Tsimane forager-farmers of lowland Bolivia. We also investigate whether female Tsimane BMD values are lower than sex- and age-matched US reference values, despite the fact that Tsimane engage in higher physical activity levels …

Age-Independent Increases In Male Salivary Testosterone During Horticultural Activity Among Tsimane Forager-Farmers, Benjamin C. Trumble, Daniel K. Cummings, Kathleen A. O'Connor, Darryl J. Holman, Eric A. Smith, Hillard Kaplan, Michael D. Gurven

ESI Publications

Testosterone plays an important role in mediating male reproductive trade-offs in many vertebrate species, augmenting muscle and influencing behavior necessary for male-male competition and mating-effort. Among humans, testosterone may also play a key role in facilitating male provisioning of offspring as muscular and neuromuscular performance are deeply influenced by acute changes in testosterone. This study examines acute changes in salivary testosterone among 63 Tsimane men ranging in age from 16–80 (mean 38.2) years during one-hour bouts of treechopping while clearing horticultural plots. The Tsimane forager-horticulturalists living in the Bolivian Amazon experience high energy expenditure associated with food production, have high …

How Universal Is The Big Five? Testing The Five-Factor Model Of Personality Variation Among Forager-Farmers In The Bolivian Amazon, Michael Gurven, Christopher Von Rueden, Maxim Massenkoff, Hillard Kaplan, Marino Lero Vie

ESI Publications

The five-factor model (FFM) of personality variation has been replicated across a range of human societies, suggesting the FFM is a human universal. However, most studies of the FFM have been restricted to literate, urban populations, which are uncharacteristic of the majority of human evolutionary history. We present the first test of the FFM in a largely illiterate, indigenous society. Tsimane forager–horticulturalist men and women of Bolivia (n = 632) completed a translation of the 44-item Big Five Inventory (Benet-Martínez & John, 1998), a widely used metric of the FFM. We failed to find robust support for the FFM, based …

From The Womb To The Tomb: The Role Of Transfers In Shaping The Evolved Human Life History, Michael Gurven, Jonathan Stieglitz, Paul L. Hooper, Cristina Gomes, Hillard Kaplan

ESI Publications

Humans are the longest living and slowest growing of all primates. Although most primates are social, humans are highly cooperative and social in ways that likely co-evolved with the slow human life history. In this paper we highlight the role of resource transfers and non-material assistance within and across generations in shaping low human mortality rates. The use of complex cooperative strategies to minimize risk is a necessary precursor for selecting further reductions in mortality rate in late adulthood. In conjunction with changes in the age-profile of production, the impacts of resource transfers and other forms of cooperation on reducing …

Infidelity, Jealousy, And Wife Abuse Among Tsimane Forager-Farmers: Testing Evolutionary Hypotheses Of Marital Conflict, Jonathan Stieglitz, Michael Gurven, Hillard Kaplan, Jeffrey Winking

ESI Publications

What causes marital conflict, and which marital conflicts are more likely to result in men’s violence against their wives? It has long been argued that men’s jealousy over women’s infidelity is the strongest impetus to men’s lethal and non-lethal violence against female partners. Less is known about the extent to which women’s jealousy over men’s infidelity precipitates men’s violence against female partners. Husbands are more likely than wives to commit infidelity, and men and women report a similar frequency and intensity of jealous emotions during recalls of potential infidelity. If men are likely to use time and resources for pursuit …

The Social Strategy Game: Resource Competition Within Female Social Networks Among Small-Scale Forager-Horticulturalists, Stacey L. Rukas, Michael Gurven, Hillard Kaplan, Jeffrey Winking

ESI Publications

This paper examines social determinants of resource competition among Tsimane Amerindian women of Bolivia. We introduce a semi-anonymous experiment (the Social Strategy Game) designed to simulate resource competition among women. Information concerning dyadic social relationships and demographic data were collected to identify variables influencing resource competition intensity, as measured by the number of beads one woman took from another. Relationship variables are used to test how the affiliative or competitive aspects of dyads affect the extent of prosociality in the game. Using a mixed-modeling procedure, we find that women compete with those with whom they are quarreling over accusations of …

A Bioeconomic Approach To Marriage And The Sexual Division Of Labor, Michael Gurven, Jeffrey Winking, Hillard Kaplan, Christopher Von Rueden, Lisa Mcallister

ESI Publications

Children may be viewed as public goods whereby both parents receive equal genetic benefits yet one parent often invests more heavily than the other.We introduce a microeconomic framework for understanding household investment decisions to address questions concerning conflicts of interest over types and amount of work effort among married men and women. Although gains and costs of marriage may not be spread equally among marriage partners, marriage is still a favorable, efficient outcome under a wide range of conditions. This bioeconomic framework subsumes both cooperative and conflictive views on the sexual division of labor. We test hypotheses concerning marriage markets, …