When in Rome do as the Romans do: The coevolution of altruistic punishment, conformist learning, and cooperation

Ricardo Andrés Guzmán, Carlos Rodríguez Sickert, Robert Rowthorn. Evolution and Human Behavior, Vol. 28, N°2, pp. 112–117, 2007.


We model the coevolution of social learning rules and behavioral strategies in the context of a cooperative dilemma, a situation in which individuals must decide whether or not to subordinate their own interests to those of the group. There are two learning rules in our model, conformism and payoff-dependent imitation, which evolve by natural selection; and three behavioral strategies, cooperate, defect, and cooperate and punish defectors, which evolve under the influence of the prevailing learning rules. Group and individual level selective pressures drive evolution.

We also simulate our model for conditions that approximate those in which early hominids lived. Contrary to previous claims, we find that conformism can evolve when the only problem individuals face is a cooperative dilemma. Furthermore, the presence of conformists dramatically increases the group size for which cooperation can be sustained. The results of our model are robust: they hold even when migration rates are high, and when conflict among groups is infrequent.