l to evolve. Those leading- eight strategies that do evolve are unable to sustain full cooperation. Author contributions: C.M., LS, J.T., K.C., and M.A.N. designed research performed esearch analyzed data. and wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct

02138, USA. These authors contributed equally: Andreas Pavlogiannis, Josef Tkadlec. Correspondence and requests for materials should be addressed to M.A.N. (email: martin_noviak@han•ard.edu) COMMUNICAIIONS BIOLOGY I (2018)1:71100110.1038/542003.016.0078.7 I wiwynalurecornkommsbto 1 EFTA00811287 ARTI