Recent studies in experimental economics have shown that many people have other-regarding preferences, potentially including preferences for altruism, reciprocity, and fairness. It is useful to investigate why people possess such preferences and what functional purpose they might serve outside the laboratory, because evolutionary and social learning perspectives both predict that cooperative sentiments should only exist if they bring benefits that outweigh the costs of other-regarding behavior. Theories of costly signaling suggest that altruistic acts may function (with or without intention) as signals of unobservable qualities such as resources or cooperative intent, and altruists may benefit (possibly unintentionally) from the advertisement of such qualities. After reviewing the theories that could potentially account for the evolution of altruism (Chapter 1), I test some predictions about cooperation derived from costly signaling theory. In Chapter 2, I show that participants in experimental public goods games were more cooperative when they had cues that they could benefit from having a good reputation, and that there was apparently some competition to be the most generous group member. Furthermore, in subsequent trust games, people tended to trust high public goods contributors more than low contributors. Chapter 3 failed to find evidence that granting high status to people makes them more likely to contribute to public goods or punish free-riders, but there was suggestive evidence that physical proximity to the experimenter affected contributions and punishment. In Chapter 4, I found that people tended to trust others who were willing to incur costs to punish those who free-ride on group cooperation provided that such punishment was justified, and men were more punitive than women. In Chapter 5, I show that women find altruistic men more desirable than neutral men for long-term relationships. Together, these results suggest that humans do treat altruism as a signal of willingness to be cooperative. These findings are discussed with respect to the adaptive design of cooperative sentiments as well as the current debate over group selection. © Economic Science Association 2006.
