Speaker: David Rand, Research Scientist, Program for Evolutionary Dynamics Psychology Department (Harvard University)
Cooperation, where one individual incurs a cost to benefit others, is a fundamental aspect of all levels of the natural world as well as human society. Yet cooperation poses a challenge to evolutionary biologists and social scientists: How can the fundamentally selfish process of natural selection favor “altruistic” cooperation, and why are humans, as strategic decision-makers, often willing to help others at a cost to themselves? In my talk, I will explore this question using a combination of evolutionary computer simulations and behavioral experiments involving economic games. I will focus particularly on the role of punishment and reward in discouraging free-riding and fostering cooperation. In the realistic context of repeated interactions where reputation is in play, I show that denial of reward promotes cooperation as effectively as costly punishment. Yet costly punishment is destructive and reduces the payoffs of both players, while denial of reward does not. Thus the use of costly punishment is detrimental to both the individual punisher and to the group as a whole. These results raise serious questions about the role of costly punishment in promoting cooperation, and emphasize the importance of developing opportunities for constructive interactions between individuals to help prevent “tragedies of the commons”.