‘Cooperation Emerges When Groups Are Small and Memories Are Long, Penn Study Finds’, https://news.upenn.edu/news/cooperation-emerges-when-groups-are-small-and-memories-are-long-penn-study-finds, THE UNIVERSITY OF PENNSYLVANIA (June 1, 2016).
Researchers use game theory to demonstrate the complex set of traits that can promote the evolution of cooperation. (…) The more players in a game the less likely that cooperative strategies could win out. (…) As a group size increases, the prospects for sustained cooperation go down. (…) The evolution of longer memories led to an increase in cooperation.