athew, S., Boyd, It, & Van Veelen, M. (2013). Human cooperation among kin and close associates may require enforcement of norms by third parties. In P. J. Richerson & M. Christiansen (Eds.), CulturatEvolution (pp. 4S-60). Cambridge Mk MIT Press. pjr» IF THIS IS TRUE—THAT "HUMAN COOPERATION AMONG KIN" and also AMONG "CLOSE ASSOC