A model is presented to account for the natural selection of what is termed reciprocally altruistic behavior. The model shows how selection can operate -against the cheater (non-reciprocator) in the system. Three instances of altruistic behavior are discussed, the evolution of which the model can explain: (1) behavior involved in cleaning symbioses; (2) warning cries in birds: and (3) human reciprocal altruism. Regarding human reciprocal altruism, it is shown that the details of the psychological system that regulates this altruism can (...) be explained by the model. Specifically, friendship,d islike, moralistic aggression, gratitude, sympathy, trust, suspicion, trustworthiness, aspects of guilt, and some forms of dishonesty and hypocrisy can be explained as important adaptations to regulate the altruistic system. Each individual human is seen as possessing altruistic and cheating tendencies, the expression of which is sensitive to developmental variables that were selected to set the tendencies at a balance appropriate to the local social and ecological environment. (shrink)

Evolutionary theories of morality, beginning with Darwin, have focused on explanations for altruism. More generally, these accounts have concentrated on conscience to the neglect of condemnation. As a result, few theoretical tools are available for understanding the rapidly accumulating data surrounding third-party judgment and punishment. Here we consider the strategic interactions among actors, victims, and third-parties to help illuminate condemnation. We argue that basic differences between the adaptive problems faced by actors and third-parties indicate that actor conscience and third-party condemnation (...) are likely performed by different cognitive mechanisms. Further, we argue that current theories of conscience do not easily explain its experimentally demonstrated insensitivity to consequences. However, these results might be explicable if conscience functions, in part, as a defense system for avoiding third-party punishment. If conscience serves defensive functions, then its computational structure should be closely tailored to the details of condemnation mechanisms. This possibility underscores the need for a better understanding of condemnation, which is important not only in itself but also for explaining the nature of conscience. We outline three evolutionary mysteries of condemnation that require further attention: third-party judgment, moralistic punishment, and moral impartiality. (shrink)

This paper provides strong evidence challenging the self-interest assumption that dominates the behavioral sciences and much evolutionary thinking. The evidence indicates that many people have a tendency to voluntarily cooperate, if treated fairly, and to punish noncooperators. We call this behavioral propensity “strong reciprocity” and show empirically that it can lead to almost universal cooperation in circumstances in which purely self-interested behavior would cause a complete breakdown of cooperation. In addition, we show that people are willing to punish those who (...) behaved unfairly towards a third person or who defected in a Prisoner’s Dilemma game with a third person. This suggests that strong reciprocity is a powerful device for the enforcement of social norms involving, for example, food sharing or collective action. Strong reciprocity cannot be rationalized as an adaptive trait by the leading evolutionary theories of human cooperation (in other words, kin selection, reciprocal altruism, indirect reciprocity, and costly signaling theory). However, multilevel selection theories of cultural evolution are consistent with strong reciprocity. (shrink)

The evolution of reciprocal altruism probably involved the evolution of mechanisms to detect cheating and remember cheaters. In a well-known study, Mealey, Daood, and Krage (1996) observed that participants had enhanced memory for faces that had previously been associated with descriptions of acts of cheating. There were, however, problems with the descriptions that were used in that study. We sought to replicate and extend the findings of Mealey and colleagues by using more controlled descriptions and by examining the possibility of (...) enhanced altruist recognition. We also examined whether individual differences in cheating tendencies were related to cheater and altruist recognition. In the first experiment, 164 undergraduates saw 40 faces that were paired with character descriptions representing the categories of cheater, trustworthy, altruist, or neutral, for individuals who had either low or high social status. One week later participants reported which faces they recognized from the previous week (among 80 faces). Overall, the results failed to replicate the findings of Mealey and her colleagues, as there was no enhanced memory for cheaters. In addition, there was no enhanced memory for altruists, and no effect of participants’ cheating tendencies. A second experiment using a slightly different methodology produced similar results, with some evidence for enhanced memory for altruists. (shrink)