The scale and complexity of human cooperation is an important and unresolved evo- lutionary puzzle. This article uses the finitely repeated n person Prisoners’ Dilemma game to illustrate how sapience can greatly enhance group-selection effects and lead to the evolutionary stability of cooperation in large groups. This affords a simple and direct explanation of the human “exception.”
Casey Rothschild (2009). The evolution of reciprocity in sizable human groups. Journal of Theoretical Biology 257, 609-617.