Cooperation emerges when groups are small and memories are long

The tragedy of the commons, a concept described by ecologist Garrett Hardin, paints a grim view of human nature. The theory goes that, if a resource is shared, individuals will act in their own self-interest, but against the interest of the group, by depleting that resource. Yet examples of cooperation and sharing abound in nature, from human societies down to single-celled bacteria. In a new paper, published in the journal Scientific Reports, University of Pennsylvania researchers use game theory to demonstrate the complex set of traits that can promote the evolution of cooperation. Their analysis showed that smaller groups in which actors had longer memories of their fellow group members’ actions were more likely to evolve cooperative strategies. The work suggests one possible advantage of the human’s powerful memory capacity: it has fed our ability as a society to cooperate.

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