Social and Behavioral Sciences Commons^™

Helminth Infection, Fecundity, And Age Of First Pregnancy In Women, Aaron D. Blackwell, Marilyne D. Tamayo, Bret Beheim, Benjamin C. Trumble, Jonathan Stieglitz, Paul L. Hooper, Melanie Martin, Hillard Kaplan, Michael Gurven

ESI Publications

Infection with intestinal helminths results in immunological changes that influence the odds of comorbid infections, and might also affect fecundity by inducing immunological states supportive of conception and pregnancy. Here we investigate associations between intestinal helminths and fertility in human females, utilizing nine years of longitudinal data from 986 Bolivian forger-horticulturalists, experiencing natural fertility and a 70% helminth prevalence. We find that different species of helminth are associated with opposing effects on fecundity. Infection with roundworm (Ascaris lumbricoides) is associated with earlier first births and shortened interbirth intervals, while infection with hookworm is associated with delayed first pregnancy and extended …

Natural Sleep And Its Seasonal Variations In Three Pre-Industrial Societies, Gandhi Yetish, Hillard Kaplan, Michael Gurven, Brian Wood, Herman Pontzer, Paul R. Manger, Charles Wilson, Ronald Mcgregor, Jerome M. Siegel

ESI Publications

How did humans sleep before the modern era? Because the tools to measure sleep under natural conditions were developed long after the invention of the electric devices suspected of delaying and reducing sleep, we investigated sleep in three preindustrial societies[1–3]. We find that all three show similar sleep organization, suggesting that they express core human sleep patterns, likely characteristic of pre-modern era Homo sapiens. Sleep periods, the times from onset to offset, averaged 6.9–8.5-h, with sleep durations of 5.7–7.1-h, amounts near the low end of those industrial societies[4–7]. There was a difference of nearly 1-h between summer and winter sleep. …

Calcaneal Quantitative Ultrasound Indicates Reduced Bone Status Among Physically Active Adult Forager-Horticulturalists, Jonathan Stieglitz, Felicia C. Madimenos, Hillard Kaplan, Michael Gurven

ESI Publications

Six months of exclusive breastfeeding (EBF) is considered optimal for infant health, though globally most infants begin complementary feeding (CF) earlier—including among populations that practice prolonged breastfeeding. Two frameworks for understanding patterns of early CF emerge in the literature. In the first, maternal and infant needs trade-off, as “maternal-centric” factors—related to time and energy demands, reproductive investment, cultural influences, and structural barriers— favor supplanting breastfeeding with earlier and increased CF. A second framework considers that “infant-centric” factors—related to infant energetic needs—favor CF before six months to supplement breastfeeding.

We apply these two frameworks in examining early CF among the Tsimane—a …

Peace Profile: Christiana Thorpe, Whitney Mcintyre Miller, Michael Wundah

Education Faculty Articles and Research

"The profile of an illustrious Sierra Leonean, Dr. Christiana Thorpe, epitomizes a success story worthy of emulation. The cultivation of sustainable peace and political stability through the eyes of social activism, service for gender parity, and electoral and education reforms are at the heart of this account. Christiana’s kind heartedness and relentless urge to labor in the service of her country and mankind make her a unique and fascinating peace maker."

Building A Better Model: Variable Selection To Predict Poverty In Pakistan And Sri Lanka, Marium Afzal, Jonathan Hersh, David Newhouse

Economics Faculty Articles and Research

Numerous studies have developed models to predict poverty, but surprisingly few have rigorously examined different approaches to developing prediction models. This paper applies out of sample validation techniques to household data from Pakistan and Sri Lanka, to compare the accuracy of regional poverty predictions from models derived using manual selection, stepwise regression, and Lasso-based procedures. It also examines how much incorporating publically available satellite data into the model improves its accuracy. The five main findings are that: 1) Lasso tends to outperform both discretionary and stepwise models in Pakistan, where the set of potential predictors is large. 2) Lasso and …

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, …

Yo Soy Latino: Does My Vote Matter?, Jonathan Charres

Student Scholar Symposium Abstracts and Posters

It has been said by many political scientists that the Latino population in the United States has the potential to be a huge political player in political elections, especially with their steady growing population. However, population growth is not translating into an increase of political participation. Although many studies have been made to understand why Latino political participation is low, I will take a different approach and focus on Latino political efficacy, comparing different states. Using the Inter-university Consortium for Political and Social Research (ICPSR) Latino National Survey, I will seek to answer whether Latinos feel more politically empowered in …

Inclusive Fitness And Differential Productivity Across The Life Course Determine Intergenerational Transfers In A Small-Scale Human Society, Paul L. Hooper, Michael Gurven, Jeffrey Winking, Hillard Kaplan

ESI Publications

Transfers of resources between generations are an essential element in current models of human life-history evolution accounting for prolonged development, extended lifespan and menopause. Integrating these models with Hamilton’s theory of inclusive fitness, we predict that the interaction of biological kinship with the age-schedule of resource production should be a key driver of intergenerational transfers. In the empirical case of Tsimane’ forager–horticulturalists in Bolivian Amazonia, we provide a detailed characterization of net transfers of food according to age, sex, kinship and the net need of donors and recipients. We show that parents, grandparents and siblings provide significant net downward transfers …

Historicity, Achronicity, And The Materiality Of Cultures In Colonial Brazil, Amy J. Buono

Art Faculty Articles and Research

"In this essay, I use three nontraditional forms from the visual culture of colonial Brazil—Tupinambá featherwork, Portuguese Atlantic mandinga pouches, and azulejos (tilework)— in order to meditate upon materiality and temporality as methodological problems with which our discipline should engage. Each of these art forms has historical trajectories that span cultures, continents, and centuries, a circumstance that raises questions as to how such diverse and stubbornly nonhistoricizable genres can be melded into a coherent historical narrative of the visual and material cultures specific to 'Brazil,' especially when two of them — the mandinga bags and azulejos — are not intrinsically …

Women And Violence In The Age Of Migration, Lilia D. Monzó, Peter Mclaren

Education Faculty Articles and Research

"Women from across Latin America are migrating north at great peril to their lives – their intended destination is, as expected, the US – that giant powerhouse that in spite of its well documented historical and continued imperialist violence and exploitation against Latin America is still able to create the ideological haze that encourages hope for that illusive “American dream.” Pushed to the brink of desperation resulting from unimaginable poverty, privation, and fear, these women muster the courage that only women of color know that they have (it is imbued in their flesh and in their hearts as a result …