There are many evolutionary pathways to Cooperation

Current sociobiological discussions attribute the evolution of cooperation to only two main influences: kinship and reciprocity. As a baseline, the paper analyzes the extent of incidental cooperation achieved in three important 2 x 2 payoff environments (Prisoners' Dilemma, Chicken, and Tender Trap) and the two simplest 'rules of the game' or protocols of play (single-round simultaneous-move and single-round sequential move). Kinship promotes cooperation beyond these base levels by modifying payoffs of selfish versus unselfish behaviors. Reciprocity may also promote cooperation, but its expression requires protocols that widen available strategy sets (in comparison with the basic strategies in the underlying 2 x 2 payoff matrices). Once payoff modifications and/or more elaborate protocols are allowed, many other pathways to cooperation are opened up. Among them are punishment options, complementary strategy mixes, recognition effects, coordination using external clues, and group selection.