The proposed training and research program in this Minority Postdoctoral Fellowship project will enable the Fellow to investigate, within an evolutionary framework, how variation in personality affects cooperative behavior. Self reported personality measures and behavior from experimental economic games will be used to test for the effects of personality on social decision making. These data will be supplemented with genetic and affective data. Based on a pilot study the Fellow conducted with Dr. Richard McElreath at the University of California, Davis, there is reason to expect that variation in the personality dimension Neuroticism, which can be described as susceptibility to negative emotions, partially predicts variation in cooperative behavior.
Receipt of this postdoctoral fellowship would give the Fellow the opportunity to be trained for two years by Dr. Daniel Nettle at the Centre for Behavior and Evolution (CBE), Newcastle University, United Kingdom. Because of his research on the evolution of personality differences, Dr. Nettle is a prime candidate for guiding the Fellow in the proposed research. Dr. Nettle has combined theory from multiple fields to successfully address questions of key evolutionary interest, as the Fellow would like to do. The diverse disciplines and expertise represented at the CBE makes it a highly suitable environment for the Fellow to strengthen her background in economics and neuroscience, further develop her modeling skills, and practice presenting her ideas and research results both formally and informally. These same qualities, as well as the research on the evolution of cooperation already underway at the CBE, also make it an optimal environment in which to integrate multimeasure data and theory from different disciplines.
Intellectual merit. Neither the proximate mechanisms for human cooperation nor the evolution of personality differences are well understood, yet both are key components for understanding one of the most compelling questions in modern biology - the evolution of human cooperation. The Fellow aims to tie these two threads together by investigating how personality affects social decision making behavior. The proposed research program is original in that it hypothesizes a relationship between two foci that have each motivated considerable bodies of research: the personality dimension of Neuroticism and human prosociality. Because of the cascade of biological, environmental, and psychological mechanisms that may precipitate social decision making, unwrapping the proximate mechanisms for prosocial behavior requires multilevel data. Based on a pilot study which supports Neuroticism as one factor that mediates prosocial behavior, further investigation of the correlation between Neuroticism and social decision making, as well as investigation of how Neuroticism and decision making each relate to affect and to a serotonergic genetic variant, is warranted. The results have the potential to advance knowledge in three distinct areas of research - the etiology of the myriad psychopathologies with which high Neuroticism is associated, the proximate mechanisms for human prosociality, and the evolution of personality differences.
Broader impacts. The proposed research program will train a female postdoctoral scientist at a crucial juncture in her academic career, as she prepares to pursue a tenure track position, and will enable her to develop collaborative relationships with international researchers in multiple disciplines. The results will be of interest to scientists in multiple fields, including those in psychology, anthropology, and economics, and hence will be published in a peer reviewed journal of broad readership. In addition, the results may offer a new, evolutionary context within which to understand high Neuroticism, which is a strong predictor of mental illnesses and was recently referred to as a significant public health risk in an article by Dr. Benjamin Lahey in the peer reviewed journal American Psychologist. In another dimension of this project, to help increase the participation of underrepresented groups in the social, behavioral and economic sciences, the Fellow will teach hands-on lessons on the evolution of human cooperation and social learning to Native Alaskan teenagers at a federally funded math and science camp.
p { margin-bottom: 0.1in; line-height: 120%; } Humans are remarkable in the degree to which they cooperate. Cooperation occurs across scales, from individuals lending resources to the coordinated self-sacrifice in an army, and across domains, from food procurement to religious displays. This propensity for cooperation has been integral to our rapid global colonization. However, it is an evolutionary puzzle. That is, a cooperator pays an immediate cost for the benefit of another individual or group. If we assume a genetic component to cooperation, individuals who reap the benefits of cooperation without cooperating ('free-riders') will do better, and leave more free-riding offspring, than those who pay the cost of cooperating. Thus, we would expect future generations to have more free-riders and fewer cooperators, destroying the possibility for cooperation. This dilemma may be solved via punishment. Free-riders may be coerced via punishment or threat of punishment. Punishment for noncooperation ranges from ostracism to death. It can be executed by a peer, peer group, or institution created to punish cooperative violations. Theoretical, experimental, and ethnographic work demonstrate that punishment can maintain cooperation. With this funding, I undertook two major projects that provide different resolution on the role of punishment in the evolution of cooperation. One investigated local variation in punishment and cooperation with the aim of understanding how noncooperation spreads. Inspiration for this project came from a body of work on variation in neighborhood crime and collective efficacy. It was conducted in two urban neighborhooods that have been the focus of behavioral research. Neighborhood A is low in crime and economically privileged. Residents exhibit higher trust and cooperative behavior on a number of measures. Neighborhood B has a high crime rate and is impoverished. Residents exhibit lower trust and cooperative behavior. Within these neighborhooods, we implemented an economic game to study the roles of punishment and perception that others are free-riders in the maintenance of cooperation. A resident was allowed to steal money from an anonymous neighbor and another neighbor could pay to fine the resident if she stole. Residents of Neighborhood A were more likely to fine thefts, irrespective of the subjective value of money. The perception in Neighorhood B that others are free-riding was central to the neighborhood difference. The causality of this was investigated by manipulating residents' perceptions of the frequency of free-riding. Our results elucidate three routes by which the perception that others are not cooperating leads to further breakdown in cooperation: 1) decreased expectation of punishment, 2) decreased peer punishment, and 3) desire not to be cheated. These results suggest real-world applications for stemming neighborhood crime and contribute to work on the cultural evolution of cooperation. The second project investigated individual variation in cooperation resulting from sensitivity to punishment. Given the costliness of being punished, I think there has been natural selection for psychological mechanisms that aid in punishment avoidance. Individual variation in processing of negative stimuli may be influenced by functional variation at two serotonin genes that are associated with mood and anxiety disorders. I hypothesized that individuals with these variants would be more cooperative and distressed when faced with the possibility of being punished for noncooperation. To test this, we asked students to play a public goods game, wherein each player receives a monetary endowment and can contribute to a group fund. The group fund is multiplied and distributed evenly among players. The financial gains to those who do not contribute can be reversed when players have the opportunity to fine each other. We assessed variation at these genes as well as personality and depression and changes in mood and cortisol during the games. A variant at one gene was associated with increased contributions when there was no punishment opportunity. A variant at the other gene was associated with increased contributions only when behavior could be punished. This variant also predicted a more stressful experience: increase in negative mood and cortisol during the game. It was not associated with increased depression or neuroticism in this study. Other molecular work suggests these variants originated recently and may have been under selection; their frequency varies around the world. These results suggest that individual variation in sensitivity to punishment can result in variation in cooperation, dependent upon the possibility of punishment. They support the idea that sensitivity to punishment may have been under selection but can also lead to negative outcomes, such as mood disorders, in certain situations. During the fellowship I also participated twice as in instructor in the Summer Internship for Native Americans in Genomics at UIUC and remained on the advisory board. The aim of this weeklong program is to increase dialogue about genomic research between indigenous Americans and scientists and to train more indigenous Americans in the genomic sciences, to work as scientists and help their communities make informed, autonomous decisions about genomic research.
