October 8, 2021, 17:00–18:00
Peer sanctioning of norm violators can explain how humans cooperate in large groups and in transient interactions with unfamiliar individuals, but it is unclear how these norms evolve. I will present three results that show how cultural evolutionary processes favor social norms that promote cooperation. 1) By examining third party punishment among the politically uncentralized Turkana pastoralists of Kenya, I will show how metanorms that regulate peer punishment can promote norm enforcement behavior. 2) Using the correspondence between the scale of cooperation and cultural variation in four neighboring pastoral groups in Kenya, I will show how group-level selection on cultural traits can explain the persistence of cooperative norms in transient interactions. 3) Based on theoretical findings, I will posit that culturally evolved norms and third party monitoring are crucial also for pairwise cooperation in repeated interactions, which can account for why reciprocity is more common in humans than other animals.