Episodic memory gives us the ability to mentally travel back in time to revisit and relive past experiences. In recent years, there has been an increased interest in the function of episodic memory. According to the orthodox view, episodic memory should be considered a part of a constructive system that simulates the future for sophisticated foresight and flexible planning. In this paper, I offer a novel alternative view. I argue that episodic memory provides invaluable information about the past behavior of (...) others, allowing us to identify reliable and trustworthy partners while avoiding dealing with cheaters. Theoretical models demonstrate that cooperation in groups can be maintained if potential partners use information about an individual’s past behavior to guide their behavior toward that individual. In these reputation-based models of human cooperation, individuals with a history of cheating are ostracized, whereas those with a history of cooperative behavior flourish. Against this theoretical background, it is possible to see a function of episodic memory in facilitating information exchange about others, helping group members make effective partner choices, and avoiding the risk of interacting with cheaters. If correct, episodic memory may have played a significant role in the evolution of human cooperation. (shrink)