Economic Theory Commons^™

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 …

Salivary Microbiomes Of Indigenous Tsimane Mothers And Infants Are Distinct Despite Frequent Premastication, Cliff S. Han, Melanie Ann Martin, Armand E.K. Dichosa, Ashlynn R. Daughton, Seth Frietze, Hillard Kaplan, Michael D. Gurven, Joe Alcock

ESI Publications

Background. Premastication, the transfer of pre-chewed food, is a common infant and young child feeding practice among the Tsimane, forager-horticulturalists living in the Bolivian Amazon. Research conducted primarily with Western populations has shown that infants harbor distinct oral microbiota from their mothers. Premastication, which is less common in these populations, may influence the colonization and maturation of infant oral microbiota, including via transmission of oral pathogens. We collected premasticated food and saliva samples from Tsimane mothers and infants (9-24 months of age) to test for evidence of bacterial transmission in premasticated foods and overlap in maternal and infant salivary …

Angels And Demons: Using Behavioral Types In A Real-Effort Moral Dilemma To Identify Expert Traits, Hernan Bejerano, Ellen P. Green, Stephen Rassenti

ESI Publications

In this article, we explore how independently reported measures of subjects' cognitive capabilities, preferences, and sociodemographic characteristics relate to their behavior in a real-effort moral dilemma experiment. To do this, we use a unique dataset, the Chapman Preferences and Characteristics Instrument Set (CPCIS), which contains over 30 standardized measures of preferences and characteristics. We find that simple correlation analysis provides an incomplete picture of how individual measures relate to behavior. In contrast, clustering subjects into groups based on observed behavior in the real-effort task reveals important systematic differences in individual characteristics across groups. However, while we find more differences, these …

Conflict Or Congruence? Maternal And Infant-Centric Factors Associated With Shorter Exclusive Breastfeeding Durations Among The Tsimane, Melanie A. Martin, Geni Garcia, Hillard Kaplan, Michael Gurven

ESI Publications

No abstract provided.

Cardiovascular Disease And Type 2 Diabetes In Evolutionary Perspective: A Critical Role For Helminths?, Michael D. Gurven, Benjamin C. Trumble, Jonathan Stieglitz, Aaron D. Blackwell, David E. Michalik, Caleb E. Finch, Hillard Kaplan

ESI Publications

Heart disease and type 2 diabetes are commonly believed to be rare among contemporary subsistencelevel human populations, and by extension prehistoric populations. Although some caveats remain, evidence shows these diseases to be unusual among well-studied hunter-gatherers and other subsistence populations with minimal access to healthcare. Here we expand on a relatively new proposal for why these and other populations may not show major signs of these diseases. Chronic infections, especially helminths, may offer protection against heart disease and diabetes through direct and indirect pathways. As part of a strategy to insure their own survival and reproduction, helminths exert multiple cardio-protective …

An Experimental Investigation Of Simultaneous Multi-Battle Contests With Complementarities, Cary Deck, Sudipta Sarangi, Matt Wiser

ESI Publications

This paper reports the results of laboratory experiments that are designed to test theoretical predictions in a multi-battle contest with value complementarities among the battles. The specific setting is a game of Hex where control of each region is determined by a Tullock contest and the overall winner is determined by the combination of claimed regions. We find that in a game with only a few regions, aggregate behavior across regions is largely consistent with the theoretical predictions. However, examining individual level behavior suggests that bidders are not behaving in accordance with the model, but often pursue specific winning combinations. …

An Epigenetic Clock Analysis Of Race/Ethnicity, Sex, And Coronary Heart Disease, Steve Horvath, Michael Gurven, Morgan E. Levine, Benjamin C. Trumble, Hillard Kaplan, Hooman Allayee, Beate R. Ritz, Brian Chen, Ake T. Lu, Tammy M. Rickabaugh, Beth D. Jamieson, Dianjianyi Sun, Shengxu Li, Wei Chen, Lluis Quintana-Murci, Maud Fagny, Michael S. Kobor, Philip S. Tsao, Alexander P. Reiner, Kerstin L. Edlefsen, Devin Absher, Themistocles L. Assimes

ESI Publications

Background: Epigenetic biomarkers of aging (the “epigenetic clock”) have the potential to address puzzling findings surrounding mortality rates and incidence of cardio-metabolic disease such as: (1) women consistently exhibiting lower mortality than men despite having higher levels of morbidity; (2) racial/ethnic groups having different mortality rates even after adjusting for socioeconomic differences; (3) the black/white mortality cross-over effect in late adulthood; and (4) Hispanics in the United States having a longer life expectancy than Caucasians despite having a higher burden of traditional cardio-metabolic risk factors.

Results: We analyzed blood, saliva, and brain samples from seven different racial/ethnic groups. …

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 …

Indirect Reciprocity, Resource Sharing, And Environmental Risk: Evidence From Field Experiments In Siberia, E. Lance Howe, James J. Murphy, Drew Gerkey, Colin Thor West

ESI Publications

Integrating information from existing research, qualitative ethnographic interviews, and participant observation, we designed a field experiment that introduces idiosyncratic environmental risk and a voluntary sharing decision into a standard public goods game. Conducted with subsistence resource users in rural villages on the Kamchatka Peninsula in Northeast Siberia, we find evidence consistent with a model of indirect reciprocity and local social norms of helping the needy. When participants are allowed to develop reputations in the experiments, as is the case in most small-scale societies, we find that sharing is increasingly directed toward individuals experiencing hardship, good reputations increase aid, and the …

Health Costs Of Reproduction Are Minimal Despite High Fertility, Mortality And Subsistence Lifestyle, Michael Gurven, Megan Costa, Ben Trumble, Jonathan Stieglitz, Bret Beheim, Daniel Eid Rodriguez, Paul L. Hooper, Hillard Kaplan

ESI Publications

Women exhibit greater morbidity than men despite higher life expectancy. An evolutionary life history framework predicts that energy invested in reproduction trades-off against investments in maintenance and survival. Direct costs of reproduction may therefore contribute to higher morbidity, especially for women given their greater direct energetic contributions to reproduction. We explore multiple indicators of somatic condition among Tsimane forager-horticulturalist women (Total Fertility Rate = 9.1; n = 592 aged 15–44 years, n = 277 aged 45+). We test whether cumulative live births and the pace of reproduction are associated with nutritional status and immune function using longitudinal data spanning 10 …

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 …

Immune Function In Amazonian Horticulturalists, Aaron D. Blackwell, Benjamin C. Trumble, Ivan Maldonado Suarez, Jonathan Stieglitz, Bret Beheim, J. Josh Snodgrass, Hillard Kaplan, Michael Gurven

ESI Publications

Background—Amazonian populations are exposed to diverse parasites and pathogens, including protozoal, bacterial, fungal, and helminthic infections. Yet much of our understanding of the immune system is based on industrialised populations where these infections are relatively rare.

Aim—We examine distributions and age-related differences in 22 measures of immune function for Bolivian forager-horticulturalists and US and European populations.

Subjects and Methods—Subjects were 6,338 Tsimane aged 0–90 years. Blood samples collected between 2004–2014 were analysed for 5-part blood differentials, C-reactive protein, erythrocyte sedimentation rate (ESR), and total immunoglobulins E, G, A, and M. Flow cytometry was used to quantify naive …

An Experimental Investigation Of Procurement Auctions With Asymmetric Sellers, John Aloysius, Cary A. Deck, Li Hao, Ryan French

ESI Publications

Electronic reverse auctions are a commonly used procurement mechanism. Research to date has focused on suppliers who are ex ante symmetric in that their costs are drawn from a common distribution. However, in many cases a seller's range of potential costs depends on their own operations, location, or economies of scale and scope. Thus, understanding how different bidder types impact auction outcomes is key when designing an auction. This paper reports the results of the first controlled laboratory experiment designed to compare prices between first-price and second-price procurement auctions for homogeneous goods when seller cost types are asymmetric and the …

State Dependent Price Setting Rules Under Implicit Thresholds: An Experiment, Justin Deloy Leblanc, Andrea Civelli, Cary A. Deck, Klajdi Bregu

ESI Publications

How firms make their pricing decisions is a fundamental question of macroeconomics. We use a laboratory experiment to examine individual choices in a price updating task that provide insight into how well state dependent models reflect behavior. We find that in general subjects behave as if they recognize the importance of a state dependent pricing strategy, but they are unable to ascertain this threshold with precision and they also exhibit a substantial degree of time dependence. As a result, they update prices too frequently, and perform statistically significantly fewer real effort profit-generating tasks than theoretically optimal under full state dependence, …

Religious Identity And The Provision Of Public Goods: Evidence From The Indian Princely States, Latika Chaudhary, Jared Rubin

ESI Publications

This paper describes a simple model of how a ruler’s religious identity affects public goods provision. Our primary insight is that rulers reduce public goods expenditures to a greater degree when there are privately-provided substitutes excludable by religion.The basic idea is that if the good is provided privately to the ruler’s co-religionists, the ruler faces weaker incentives to provide this public good because his co-religionists receive lower marginal utility from its provision. Testing such a conjecture is an empirical challenge, however, since the religious identity of rulers rarely varies over time and place. We address this problem by exploiting …

The Financial Power Of The Powerless: Socio-Economic Status And Interest Rates Under Weak Rule Of Law, Timur Kuran, Jared Rubin

ESI Publications

In advanced economies interest rates vary inversely with the borrower's socio-economic status, which itself depends inversely on default risk. These relationships depend on the impartiality of the law. Where the law is markedly biased in favour of certain groups, the latter will pay a surcharge for capital. Legal power, as measured by privileges before the law, thus undermines financial power, the capacity to borrow cheaply. Developing this argument, this paper also tests it through judicial records from Ottoman Istanbul, 1602-1799. Three privileged Ottoman groups—men, Muslims, and titled elites—all paid relatively high interest rates conditional on various loan characteristics.