Testing models of non-kin cooperation: mutualism and the Prisoner’s Dilemma

Abstract

Since 1981, the iterated Prisoner's Dilemma has dominated studies of non-kin cooperation. Alternative models have received relatively little attention. The simplest alternative is mutualism, in which mutual cooperation always pays best. The behaviour of three pairs of blue jays,Cyanocitta cristata, was tested in precisely controlled iterated mutualism and Prisoner's Dilemma games. Although the jays readily cooperated in the mutualism game, cooperation neither developed nor persisted in a Prisoner's Dilemma. No empirical justification was found for the status of the iterated Prisoner's Dilemma as the basic paradigm of non-kin cooperation.