A comparison of the Moran Process and replicator equations for evolving social dilemma game strategies.

Social dilemma games are studied to gain insight into why humans cooperate with other unrelated people. The canonical game has cooperation and defection as the two strategies. Cooperation benefits the group, but a self-interested player can always do better by defecting.

When is altruistic punishment useful in social dilemmas?

It is not fully understood how cooperation emerges in a population of individuals with no connections or prior experience with each other. Strategy selection that is purely based on accumulated payoffs promotes free riders who put their self interests above that of any group. How could cooperation persist in these settings? Researchers have posited direct or indirect reciprocity as possible explanations but these theories fail if interactions are not repeated or reputations are ignored.