The Evolution of Social Contracts

Influential thinkers such as Young, Sugden, Binmore, and Skyrms have developed game-theoretic accounts of the emergence, persistence and evolution of social contracts. Social contracts are sets of commonly understood rules that govern cooperative social interaction within societies. These naturalistic accounts provide us with valuable and important insights into the foundations of human societies. However, current naturalistic theories focus mainly on how social contracts solve coordination problems in which the interests of the individual participants are aligned, not competition problems in which individual interests compete with group interests. In response, I set out to build on those theories and provide a comprehensive naturalistic account of the emergence, persistence and evolution of social contracts. My central claim is that social contracts have culturally evolved to solve cooperation problems, which include both coordination and competition problems. I argue that solutions to coordination problems emerge from “within-group” dynamics, while solutions to competition problems result largely from “between-group” dynamics

The evolution of barriers to exploitation: Sometimes the Red Queen can take a break.

We propose a general barrier theory as an evolutionary framework for understanding coevolutionary effects of conflicts of interest in natural and human systems. It is generalized from the barrier theory of cancer, which describes how cancer develops through the evasion of mechanisms, that block unregulated cellular reproduction and survival. Barriers are naturally evolved or artificially implemented mechanisms for blocking exploitation; restraints are mechanisms that impede but do not block exploitation. When conflicts of interest arise, selection will favor exploiters that are capable of overcoming barriers and restraints. When barriers are in place, they halt, at least temporarily, coevolutionary arms races (the Red Queen can stop running). Barriers occur in a broad spectrum of interactions characterized by conflicts of interest: barriers to cellular survival (apoptosis) and reproduction (cell cycle arrest) may block a virus from replicating its genome through reproduction of its host cell. Vaccines may completely protect against targeted pathogens. A plant may escape herbivory by evolving defensive chemicals that block herbivory. Obligate mutualisms may evolve when barriers to horizontal transmission favor symbionts that increasingly lose mechanisms that contribute to horizontal transmission. Here, we show how the barrier theory applies across a spectrum of natural and social systems

Why We Help The Wronged: Emotional And Evolutionary Determinants Of Victim Compensation

Why do third parties choose to help the victims of norm violations? In Chapter 1, we address this question at the emotional level. We show a relationship between environment and motivating emotion, in which moral outrage motivates the compensation of norm violation victims, whereas empathic concern drives compensation in other situations, at both the trait (Study 1) and state (Studies 2 and 3) levels. This finding presents a novel question for evolutionary psychology. Differing emotional drivers are taken to represent distinct underlying cognitive systems. While previous evolutionary models based on social insurance through indirect reciprocity can account for domain-general empathically driven compensation, they fail to address morally outraged compensation of norm violation victims. In Chapter 2, we extend two evolutionary models of punishment, showing how those same selection pressures may also account for victim compensation. We first propose the reputation-signaling hypothesis, under which compensators signal their community status and knowledge of local norms, making observers more likely to select them as future interaction partners. We also develop the norm stabilization hypothesis, in which compensators broadcast their endorsement of the violated norm, leading conditional conformists to continue to comply, thereby stabilizing the norm within the group. In Chapter 3, we develop and test empirical predictions of both hypotheses. In Study 4, we find support for the joint prediction of both the reputation-signaling and norm stabilization hypotheses that compensation is increased when observed by others. In Study 5, we show that, consistent with the norm stabilization hypothesis, those who observe compensation of a victim of a norm violation are more likely to conform to that norm. In Study 6, we test the prediction of the reputation-signaling hypothesis that those who compensate are preferred as interaction partners to those who act similarly pro-socially, but not through compensation. Here we find mixed results, with compensators being preferred to those who show general pro-sociality, but less attractive than those who conform to an unrelated norm. Together, this work provides the first emotional and evolutionary account for the compensation of norm violation victims

Parasite-stress promotes in-group assortative sociality: the cases of strong family ties and heightened religiosity

Throughout the world people differ in the magnitude with which they value strong family ties or heightened religiosity. We propose that this cross-cultural variation is a result of a contingent psychological adaptation that facilitates in-group assortative sociality in the face of high levels of parasite-stress while devaluing in-group assortative sociality in areas with low levels of parasite-stress. This is because in-group assortative sociality is more important for the avoidance of infection from novel parasites and for the management of infection in regions with high levels of parasite-stress compared with regions of low infectious disease stress. We examined this hypothesis by testing the predictions that there would be a positive association between parasite-stress and strength of family ties or religiosity. We conducted this study by comparing among nations and among states in the United States of America. We found for both the international and the interstate analyses that in-group assortative sociality was positively associated with parasite-stress. This was true when controlling for potentially confounding factors such as human freedom and economic development. The findings support the parasite-stress theory of sociality, that is, the proposal that parasite-stress is central to the evolution of social life in humans and other animals

“Economic man” in cross-cultural perspective: Behavioral experiments in 15 small-scale societies

Researchers from across the social sciences have found consistent deviations from the predictions of the canonical model of self-interest in hundreds of experiments from around the world. This research, however, cannot determine whether the uniformity results from universal patterns of human behavior or from the limited cultural variation available among the university students used in virtually all prior experimental work. To address this, we undertook a cross-cultural study of behavior in ultimatum, public goods, and dictator games in a range of small-scale societies exhibiting a wide variety of economic and cultural conditions. We found, first, that the canonical model – based on self-interest – fails in all of the societies studied. Second, our data reveal substantially more behavioral variability across social groups than has been found in previous research. Third, group-level differences in economic organization and the structure of social interactions explain a substantial portion of the behavioral variation across societies: the higher the degree of market integration and the higher the payoffs to cooperation in everyday life, the greater the level of prosociality expressed in experimental games. Fourth, the available individual-level economic and demographic variables do not consistently explain game behavior, either within or across groups. Fifth, in many cases experimental play appears to reflect the common interactional patterns of everyday life

Signals of belonging: emergence of signalling norms as facilitators of trust and parochial cooperation

Mechanisms of social control reinforce norms that appear harmful or wasteful, such as mutilation practices or extensive body tattoos. We suggest such norms arise to serve as signals that distinguish between ingroup “friends” and outgroup “foes”, facilitating parochial cooperation. Combining insights from research on signalling and parochial cooperation, we incorporate a trust game with signalling in an agent-based model to study the dynamics of signalling norm emergence in groups with conflicting interests. Our results show that costly signalling norms emerge from random acts of signalling in minority groups that benefit most from parochial cooperation. Majority groups are less likely to develop costly signalling norms. Yet, norms that prescribe sending costless group identity signals can easily emerge in groups of all sizes – albeit, at times, at the expense of minority group members. Further, the dynamics of signalling norm emergence differ across signal costs, relative group sizes, and levels of ingroup assortment. Our findings provide theoretical insights into norm evolution in contexts where groups develop identity markers in response to environmental challenges that put their interests at odds with the interests of other groups. Such contexts arise in zones of ethnic conflict or during contestations of existing power relations

Networks of reliable reputations and cooperation: a review

Reputation has been shown to provide an informal solution to the problem of cooperation in human societies. After reviewing models that connect reputations and cooperation, we address how reputation results from information exchange embedded in a social network that changes endogenously itself. Theoretical studies highlight that network topologies have different effects on the extent of cooperation, since they can foster or hinder the flow of reputational information. Subsequently, we review models and empirical studies that intend to grasp the coevolution of reputations, cooperation and social networks. We identify open questions in the literature concerning how networks affect the accuracy of reputations, the honesty of shared information and the spread of reputational information. Certain network topologies may facilitate biased beliefs and intergroup competition or in-group identity formation that could lead to high cooperation within but conflicts between different subgroups of a network. Our review covers theoretical, experimental and field studies across various disciplines that target these questions and could explain how the dynamics of interactions and reputations help or prevent the establishment and sustainability of cooperation in small- and large-scale societies

The survival of the kindest: a theoretical review and empirical investigation of explanations to the evolution of human altruism

Charles Darwin was concerned that his entire theory of evolution by natural selection might be negated by a phenomenon prevalent in a variety of species including humans; namely altruism. If natural selection really favored the survival of the fittest, how could a strategy so irrational as to sacrifice oneself for the well-being of unrelated others survive? A number of scientists have contributed valuable theories to elucidate the �paradox of altruism�. However, in spite of the merits of these theories, there is still dissension about the origins of some particular oddities in the altruistic tendencies of humans, namely why humans act selflessly even when they are unobserved and when they are benefiting a stranger whom they will never meet again. The present doctoral thesis sheds light on answers to the question how human altruism, with all its specific features, could evolve. In the first part, both prominent (e.g., kin selection, reciprocal altruism, etc.) and less recognized theories on the evolution of altruism (e.g., green-beard altruism, the theory of the extended phenotype, etc.) are reviewed. Based on an integrative overview, it is analyzed how much of the altruism puzzle has been solved yet and which specific phenomena are still open to conjecture. With the aim of adding new insights to the issue, the second part of this work presents three empirical studies that investigate in how far prosociality might have been favored (1) by processes of assortation, i.e. the grouping of altruists, and (2) by mating strategies. Indeed, assortation may be invoked as an explanation for the evolution of altruism, if the selfish advantage of egoistic individuals is out-competed by benefits of mutually cooperating altruists. However, to make assortation work as a driver of the evolution of altruism, two prerequisites have to be fulfilled: first, individuals have to be able to distinguish altruists from egoists, and second, altruists have to elect like-minded individuals for mutual cooperation. The first study investigates whether humans are really able to identify altruists based on first impression. To test this, judges watched 20-second silent video clips of unknown target persons and were asked to estimate the behavior of these target persons in a dictator game, which measures prosociality. Estimates were significantly better than chance indicating that humans can identify the altruistic dispositions of unknown persons. The second study investigates whether individuals, in genuine groups, can identify the altruistic tendencies of their daily interaction partners. It further examines whether prosociality influences the formation of friendships in such that individuals assort themselves along the dimension of altruism. Students of six secondary school classes played an anonymous dictator game that functioned as a measure of altruism. Afterwards and unannounced, the students had to estimate their classmates� decisions and did so better than chance. Sociometry revealed that altruists were friends with more altruistic persons than were egoists. The results thus confirm the existence of the two prerequisites for the evolution of altruism through assortation: the predictability of altruistic behavior and the association of altruists. However, although the theory of assortation may explain the evolution of altruism in general, it does not explain the occurrence of inter-individual differences in altruism. The third study deals exactly with this matter. It investigates whether different levels of prosociality might have evolved as a result of different mating strategies, namely inter-individual variations in the propensity to engage in either short-term mating or long-term mating. Specifically, it assumes that prosociality is a necessity for acquiring a long-term partner, especially if an individual has to compensate for deficits in physical attractiveness. To find out whether this idea is true, the study tested whether individuals look out for different levels of prosociality depending on whether they are searching for a short-term mate or a long-term mate. Judges watched short video-clips of target persons and received additional information on the targets� prosociality. Judges were then asked to rate each of the target persons with regard to their desirability as a short-term and long-term mate. While prosociality was a significant predictor for long-term desirability, it was irrelevant when subjects chose a short-term mate. The results suggest that although altruism is costly, at least for some individuals it might be a wretched necessity to obtain access to mates and to reproduce. In the general discussion, the results of all three studies are consolidated. Conclusions are drawn as to the consequences of these findings for the study of human altruism. Finally, directions for future research are presented