Economic Theory Commons^™

Do Truth-Telling Oaths Improve Honesty In Crowd-Working?, Nicolas Jacquemet, Alexander G. James, Stéphane Luchini, James J. Murphy, Jason F. Shogren

ESI Publications

This study explores whether an oath to honesty can reduce both shirking and lying among crowd-sourced internet workers. Using a classic coin-flip experiment, we first confirm that a substantial majority of Mechanical Turk workers both shirk and lie when reporting the number of heads flipped. We then demonstrate that lying can be reduced by first asking each worker to swear voluntarily on his or her honor to tell the truth in subsequent economic decisions. Even in this online, purely anonymous environment, the oath significantly reduced the percent of subjects telling “big” lies (by roughly 27%), but did not affect shirking. …

Quantitative Description Of The Pastoral Economy Of Western Tuvan Nomads, Paul L. Hooper

ESI Publications

Nomadic pastoralism persists at a substantial scale in Tuva and neighboring regions of Inner Asia. Tuvan pastoral lifeways reflect adaptations to both local environments and current economic realities. Much of our quantitative understanding of the economics of Tuvan nomads is derived from data collected in the first half of the 20th century. Accordingly, this paper provides an updated picture of the inner workings of nomadic households using data collected in Barun-Khemchik and Bai-Taiga provinces in 2013–2015. It analyzes herd composition and size, and compares the frequency of different animals kept today with values recorded in Tuva in 1916 and 1931. …

Productivity Loss Associated With Functional Disability In A Contemporary Small-Scale Subsistence Population, Jonathan Stieglitz, Paul L. Hooper, Benjamin C. Trumble, Hillard Kaplan, Michael D. Gurven

ESI Publications

In comparative cross-species perspective, humans experience unique physical impairments with potentially large consequences. Quantifying the burden of impairment in subsistence populations is critical for understanding selection pressures underlying strategies that minimize risk of production deficits. We examine among forager-horticulturalists whether compromised bone strength (indicated by fracture and lower bone mineral density, BMD) is associated with subsistence task cessation. We also estimate the magnitude of productivity losses associated with compromised bone strength. Fracture is associated with cessation of hunting, tree chopping, and walking long distances, but not tool manufacture. Age-specific productivity losses from hunting cessation associated with fracture and lower BMD …

Deliberation Enhances The Confirmation Bias In Politics, David L. Dickinson

ESI Publications

The confirmation bias, unlike other decision biases, has been shown both empirically and in theory to be enhanced with deliberation. This suggests that limited attention, reduced deliberation, or limited available cognitive resources may moderate this bias. We aimed to test this hypothesis using a validated confirmation bias task in conjunction with a protocol that randomly assigned individuals to one week of at-home sleep restriction (SR) or well-rested (WR) sleep levels. We also used a measure of cognitive reflection as an additional proxy for deliberation in our analysis. We tested the hypotheses that the confirmation bias would be stronger for WR …

The Effect Of Sleep On Public Good Contributions And Punishment: Experimental Evidence, Jeremy Clark, David L. Dickinson

ESI Publications

We investigate the effect of a full week of sleep restriction (SR) vs. well-restedness (WR) on contributions in a common public good experiment, the voluntary contributions mechanism (VCM). We examine the effect of sleep manipulation on decisions regarding both contributions and punishment of non-contributors. Actigraphy devices are used to confirm that our random assignment to sleep condition generates significant differences in objective nightly sleep duration and sleepiness. We find that when punishment is unavailable public good contributions do not differ by SR/WR assignment. When punishment is available, we find evidence that SR subjects contribute more than WR subjects, respond more …

Rapidly Declining Body Temperature In A Tropical Human Population, Michael Gurven, Thomas Kraft, Sarah Alami, Juan Copajira Adrian, Edhitt Cortez Linares, Daniel Cummings, Daniel Eid Rodriguez, Paul L. Hooper, Adrian Jaeggi, Raul Quispe Gutierrez, Ivan Maldonado Suarez, Edmond Seabright, Hillard Kaplan, Jonathan Stieglitz, Benjamin C. Trumble

ESI Publications

Normal human body temperature (BT) has long been considered to be 37.0°C. Yet, BTs have declined over the past two centuries in the United States, coinciding with reductions in infection and increasing life expectancy. The generality of and reasons behind this phenomenon have not yet been well studied. Here, we show that Bolivian forager-farmers (n = 17,958 observations of 5481 adults age 15+ years) inhabiting a pathogen-rich environment exhibited higher BT when first examined in the early 21st century (~37.0°C). BT subsequently declined by ~0.05°C/year over 16 years of socioeconomic and epidemiological change to ~36.5°C by 2018. As predicted, …

The Role Of Dispersal And School Attendance On Reproductive Dynamics In Small, Dispersed Populations: Choyeros Of Baja California Sur, Mexico, Shane Macfarlan, Ryan Schacht, Eric Schniter, Juan José Garcia, Diego Guevara Beltran, Jory Lerback

ESI Publications

Individuals from small populations face challenges to initiating reproduction because stochastic demographic processes create local mate scarcity. In response, flexible dispersal patterns that facilitate the movement of individuals across groups have been argued to reduce mate search costs and inbreeding depression. Furthermore, factors that aggregate dispersed peoples, such as rural schools, could lower mate search costs through expansion of mating markets. However, research suggests that dispersal and school attendance are costly to fertility, causing individuals to delay marriage and reproduction. Here, we investigate the role of dispersal and school attendance on marriage and reproductive outcomes using a sample of 54 …

Evidence For Height And Immune Function Trade-Offs Among Preadolescents In A High Pathogen Population, Angela R. Garcia, Aaron Blackwell, Benjamin C. Trumble, Jonathan Stieglitz, Hillard Kaplan, Michael Gurven

ESI Publications

Background

In an energy-limited environment, caloric investments in one characteristic should trade-off with investments in other characteristics. In high pathogen ecologies, biasing energy allocation towards immune function over growth would be predicted, given strong selective pressures against early-life mortality.

Methodology

In the present study, we use flow cytometry to examine trade-offs between adaptive immune function (T cell subsets, B cells), innate immune function (natural killer cells), adaptive to innate ratio and height-for-age z scores (HAZ) among young children (N = 344; aged 2 months–8 years) in the Bolivian Amazon, using maternal BMI and child weight-for-height z scores (WHZ) as …

Multiplex Network Ties And The Spatial Diffusion Of Radical Innovations: Martin Luther’S Leadership In The Early Reformation, Sascha O. Becker, Yuan Hsiao, Steven Pfaff, Jared Rubin

ESI Publications

This article analyzes Martin Luther’s role in spreading the early Reformation, one of the most important episodes of radical institutional change in the last millennium. We argue that social relations played a key role in its diffusion because the spread of heterodox ideologies and their eventual institutionalization relied not only on private “infection” through exposure to innovation but also on active conversion and promotion of that new faith through personal ties. We conceive of that process as leader-to-follower directional influence originating with Luther and flowing to local elites through personal ties. Based on novel data on Luther’s correspondence, Luther’s visits, …

A Simple, Ecologically Rational Rule For Settling Found Property Disputes, Bart J. Wilson

ESI Publications

Who has property in a found item X, which is contained in Y? The finder of X or the person who has property in Y? The common law says it depends. It depends upon whether the owner of Y knew about X, or whether X was lost or mislaid, or how small the weight of X is relative to Y (as compared to its value), or whether the finder was an employee of the owner of Y, to name just a few. Wilson (2020) hypothesizes that humans universally cognize property as being contained in a …

Consistent Differences In A Virtual World Model Of Ape Societies, Bart J. Wilson, Sarah F. Brosnan, Elizabeth V. Lonsdorf, Crickette M. Sanz

ESI Publications

Practical and ethical constraints limit our ability to experimentally test socioecological theory in wild primates. We took an alternate approach to model this, allowing groups of humans to interact in a virtual world in which they had to find food and interact with both ingroup and outgroup avatars to earn rewards. We altered ratios and distributions of high- and low-value foods to test the hypothesis that hominoids vary with regards to social cohesion and intergroup tolerance due to their feeding ecology. We found larger nesting clusters and decreased attacks on outgroup competitors in the Bonobo condition versus the Chimpanzee condition, …

Immune Function During Pregnancy Varies Between Ecologically Distinct Populations, Carmen Hové, Benjamin C. Trumble, Amy S. Anderson, Jonathan Stieglitz, Hillard Kaplan, Michael Gurven, Aaron Blackwell

ESI Publications

Background and objectives

Among placental mammals, females undergo immunological shifts during pregnancy to accommodate the fetus (i.e. fetal tolerance). Fetal tolerance has primarily been characterized within post-industrial populations experiencing evolutionarily novel conditions (e.g. reduced pathogen exposure), which may shape maternal response to fetal antigens. This study investigates how ecological conditions affect maternal immune status during pregnancy by comparing the direction and magnitude of immunological changes associated with each trimester among the Tsimane (a subsistence population subjected to high pathogen load) and women in the USA.

Methodology

Data from the Tsimane Health and Life History Project (N = 935) and …

Paternal Provisioning Results From Ecological Change, Ingela Alger, Paul L. Hooper, Donald Cox, Jonathan Stieglitz, Hillard S. Kaplan

ESI Publications

Paternal provisioning is ubiquitous in human subsistence societies and unique among apes. How could paternal provisioning have emerged from promiscuous or polygynous mating systems that characterize other apes? An anomalous provisioning male would encounter a social dilemma: Since this investment in prospective offspring can be expropriated by other males, this investment is unlikely to increase the provisioner’s fitness. We present an ecological theory of the evolution of human paternal investment. Ecological change favoring reliance on energetically rich, difficult-to-acquire resources increases payoffs to paternal provisioning due to female–male and/or male–male complementarities. Paternal provisioning becomes a viable reproductive strategy when complementarities are …

Asset Price Volatility And Price Extrema, Carey Caginalp, Gunduz Caginalp

ESI Publications

The relationship between price volatility and expected price market extremum is examined using a fundamental economics model of supply and demand. By examining randomness through a microeconomic setting, we obtain the implications of randomness in the supply and demand, rather than assuming that price has randomness on an empirical basis. Within a general setting of changing fundamentals, the volatility is maximum when expected prices are changing most rapidly, with the maximum of volatility reached prior to the maximum of expected price. A key issue is that randomness arises from the supply and demand, and the variance in the stochastic differential …

News-Driven Expectations And Volatility Clustering, Sabiou M. Inoua

ESI Publications

Financial volatility obeys two fascinating empirical regularities that apply to various assets, on various markets, and on various time scales: it is fat-tailed (more precisely power-law distributed) and it tends to be clustered in time. Many interesting models have been proposed to account for these regularities, notably agent-based models, which mimic the two empirical laws through a complex mix of nonlinear mechanisms such as traders switching between trading strategies in highly nonlinear way. This paper explains the two regularities simply in terms of traders’ attitudes towards news, an explanation that follows from the very traditional dichotomy of financial market participants, …

Nonbinding Goals In Teams: A Real Effort Coordination Experiment, James Fan, Joaquin Gómez-Miñambres

ESI Publications

Problem definition: We investigate the impact of nonbinding (wage-irrelevant) goals, set by a manager, on a team of workers with “weak-link” production technology. Can nonbinding goals improve team production when team members face production complementarity? Academic/practical relevance: Nonbinding goals are easy to implement and ubiquitous in practice. These goals have been shown to improve individual performance, but it remains to be seen if such goals are effective in team production when there is production complementarity among workers. Methodology: We first develop a theoretical model where goals act as reference points for workers’ intrinsic motivation to complete the …

Computed Tomography Shows High Fracture Prevalence Among Physically Active Forager-Horticulturalists With High Fertility, Jonathan Stieglitz, Benjamin C. Trumble, Horus Study Team, Caleb E. Finch, Dong Li, Matthew J. Budoff, Hillard Kaplan, Michael D. Gurven

ESI Publications

Modern humans have more fragile skeletons than other hominins, which may result from physical inactivity. Here, we test whether reproductive effort also compromises bone strength, by measuring using computed tomography thoracic vertebral bone mineral density (BMD) and fracture prevalence among physically active Tsimane forager-horticulturalists. Earlier onset of reproduction and shorter interbirth intervals are associated with reduced BMD for women. Tsimane BMD is lower versus Americans, but only for women, contrary to simple predictions relying on inactivity to explain skeletal fragility. Minimal BMD differences exist between Tsimane and American men, suggesting that systemic factors other than fertility (e.g. diet) do not …

A Dynamical Systems Approach To Cryptocurrency Stability, Carey Caginalp

ESI Publications

Recently, the notion of cryptocurrencies has come to the fore of public interest. These assets that exist only in electronic form, with no underlying value, offer the owners some protection from tracking or seizure by government or creditors. We model these assets from the perspective of asset flow equations developed by Caginalp and Balenovich, and investigate their stability under various parameters, as classical finance methodology is inapplicable. By utilizing the concept of liquidity price and analyzing stability of the resulting system of ordinary differential equations, we obtain conditions under which the system is linearly stable. We find that trend-based motivations …

The Dynamics Of Men's Cooperation And Social Status In A Small-Scale Society, Christopher Von Rueden, Daniel Redhead, Rick O'Gorman, Hillard Kaplan, Michael Gurven

ESI Publications

We propose that networks of cooperation and allocation of social status co-emerge in human groups. We substantiate this hypothesis with one of the first longitudinal studies of cooperation in a preindustrial society, spanning 8 years. Using longitudinal social network analysis of cooperation among men, we find large effects of kinship, reciprocity and transitivity in the nomination of cooperation partners over time. Independent of these effects, we show that (i) higher-status individuals gain more cooperation partners, and (ii) individuals gain status by cooperating with individuals of higher status than themselves. We posit that human hierarchies are more egalitarian relative to other …

Kinship Ties Across The Lifespan In Human Communities, Jeremy Koster, Dieter Lukas, David Nolin, Eleanor Power, Alexandra Alvergne, Ruth Mace, Cody T. Ross, Karen Kramer, Russell Graves, Mark Caudell, Shane Macfarlan, Eric Schniter, Robert Quinlan, Siobhan Mattison, Adam Reynolds, Chun Yi-Sim, Eric Massengill

ESI Publications

A hypothesis for the evolution of long post-reproductive lifespans in the human lineage involves asymmetries in relatedness between young immigrant females and the older females in their new groups. In these circumstances, inter-generational reproductive conflicts between younger and older females are predicted to resolve in favor of the younger females, who realize fewer inclusive fitness benefits from ceding reproduction to others. This conceptual model anticipates that immigrants to a community initially have few kin ties to others in the group, gradually showing greater relatedness to group members as they have descendants who remain with them in the group. We examine …

Nonlinear Price Dynamics Of S&P 100 Stocks, Gunduz Caginalp, Mark Desantis

ESI Publications

The methodology presented provides a quantitative way to characterize investor behavior and price dynamics within a particular asset class and time period. The methodology is applied to a data set consisting of over 250,000 data points of the S&P 100 stocks during 2004-2018. Using a two-way fixed-effects model, we uncover trader motivations including evidence of both under- and overreaction within a unified setting. A nonlinear relationship is found between return and trend suggesting a small, positive trend increases the return, while a larger one tends to decrease it. The shape parameters of the nonlinearity quantify trader motivation to buy into …

Commentary: Reflections On Decision Research And Its Empiricism: Four Comments Inspired By Harrison, Nathaniel T. Wilcox

ESI Publications

"Generally I find Harrison's chapter cogent, interesting, and well-informed in details and particulars, and so do not speak of them. Instead, I reflect on four larger matters Harrison brings to my mind. These four matters are presented below as four separate sections, to be read as four separate and short comments (though the four sections do share a few threads)."

Establishing Cryptocurrency Equilibria Through Game Theory, Carey Caginalp, Gunduz Caginalp

ESI Publications

We utilize optimization methods to determine equilibria of cryptocurrencies. A core group, the wealthy, fears the loss of assets that can be seized by a government. Volatility may be influenced by speculators. The wealthy must divide their assets between the home currency and the cryptocurrency, while the government decides the probability of seizing a fraction the assets of this group. We establish conditions for existence and uniqueness of Nash equilibria. Also examined is the separate timescale problem in which the government policy cannot be reversed, while the wealthy can adjust their allocation in reaction to the government’s designation of probability.

Methodological Differences Cannot Explain Associations Between Health, Anthropometrics, And Excess Resting Metabolic Rate, Michael Gurven, Benjamin Trumble, Jonathan Stieglitz, Dan Cummings, Hillard Kaplan, Aaron D. Blackwell, Gandhi Yetish, Herman Pontzer

ESI Publications

"We appreciate Ocobock's interest in methodological rigor. We largely agree with her commentary, which suggests that departures from standard protocols might have contributed to the high resting metabolic rate (RMR) measured for Tsimane. Indeed, our paper acknowledges many of the key departures from gold-standard indirect calorimetry methods of RMR assessment and attempts to adjust for several of these (Gurven et al., 2016). Bringing standard clinical methods into remote field settings often involves certain compromises, especially in our case, where RMR measurement was just one component of a large-scale health and aging project (Gurven et al., 2017). RMR data collection was …

On The Merit Of Equal Pay: Performance Manipulation And Incentive Setting, Brice Corgnet, Ludivine Martin, Peguy Ndodjang, Angela Sutan

ESI Publications

Work performance is often difficult to assess thus leaving room for manipulation of commonly-used metrics. We created a laboratory workplace in which we can precisely assess both work performance along with manipulation activities. Using two independent experiments we show that, whenever pay for performance is used, manipulation is pervasive leading to both a waste of organizational resources and a weakening of incentives. By contrast, paying organizational members equally effectively deters manipulation attempts leading to higher organizational production.

Coordination And Evolutionary Dynamics: When Are Evolutionary Models Reliable?, Daniel Graydon Stephenson

ESI Publications

This study reports a continuous-time experimental test of evolutionary models in coordinated attacker–defender games. It implements three experimental treatment conditions: one with strong coordination incentives, one with weak coordination incentives, and one with zero coordination incentives. Each treatment exhibits identical equilibrium predictions but distinct evolutionary predictions. Observed behavior was tightly clustered around equilibrium under both the zero coordination treatment and the weak coordination treatment but widely dispersed from equilibrium under the strong coordination treatment. This result was anticipated by explicitly dynamic models but not by conventional stability criteria. In contrast to the widely maintained assumption of sign-preservation, subjects frequently switched …

Variation Among Populations In The Immune Protein Composition Of Mother's Milk Reflects Subsistence Pattern, Laura D. Klein, Jincui Huang, Elizabeth A. Quinn, Melanie A. Martin, Alicia A. Breakey, Michael Gurven, Hillard Kaplan, Claudia Valeggia, Grazyna Jasienska, Brooke Scelza, Carlito B. Lebrilla, Katie Hinde

ESI Publications

Lay Summary: Adaptive immune proteins in mothers’ milk are more variable than innate immune proteins across populations and subsistence strategies. These results suggest that the immune defenses in milk are shaped by a mother’s environment throughout her life.

Background and objectives: Mother’s milk contains immune proteins that play critical roles in protecting the infant from infection and priming the infant’s developing immune system during early life. The composition of these molecules in milk, particularly the acquired immune proteins, is thought to reflect a mother’s immunological exposures throughout her life. In this study, we examine the composition of innate …

Do Negative Random Shocks Affect Trust And Trustworthiness?, Hernán Bejerano, Joris Gillet, Ismael Rodriguez-Lara

ESI Publications

We report data from a variation of the trust game aimed at determining whether (and how) inequality and random shocks that affect wealth influence the levels of trust and trustworthiness. To tease apart the effect of the shock and the inequality, we compare behavior in a trust game where the inequality is initially given and one where it is the result of a random shock that reduces the second mover's endowment. We find that first‐movers send less to second‐movers but only when the inequality results from a random shock. As for the amount returned, second‐movers return less when they are …

Do Negative Random Shocks Affect Trust And Trustworthiness?, Hernán Bejerano, Joris Gillet, Ismael Rodriguez-Lara

ESI Publications

We report data from a variation of the trust game aimed at determining whether (and how) inequality and random shocks that affect wealth influence the levels of trust and trustworthiness. To tease apart the effect of the shock and the inequality, we compare behavior in a trust game where the inequality is initially given and one where it is the result of a random shock that reduces the second mover's endowment. We find that first‐movers send less to second‐movers but only when the inequality results from a random shock. As for the amount returned, second‐movers return less when they are …

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 …