title: Human cooperation: second-order free-riding problem solved?
abstract: Panchanathan and Boyd describe a model of indirect reciprocity in which mutual aid among cooperators can promote large-scale human cooperation without succumbing to a second-order free-riding problem (whereby individuals receive but do not give aid). However, the model does not include second-order free riders as one of the possible behavioural types. Here I present a simplified version of their model to demonstrate how cooperation unravels if second-round defectors enter the population, and this shows that the free-riding problem remains unsolved.
authors.affiliation: Department of Political Science, University of California at Davis, One Shields Avenue, Davis, California 95616, USA jhfowler@ucdavis.edu
authors.forename: James H
authors.initials: JH
authors.lastname: Fowler
mesh_terms: D003299:Cooperative Behavior; D005716:Game Theory; D006801:Humans; D011336:Probability; D011678:Punishment