title: Variants at serotonin transporter and 2A receptor genes predict cooperative behavior differentially according to presence of punishment.
abstract: Punishment of free-riding has been implicated in the evolution of cooperation in humans, and yet mechanisms for punishment avoidance remain largely uninvestigated. Individual variation in these mechanisms may stem from variation in the serotonergic system, which modulates processing of aversive stimuli. Functional serotonin gene variants have been associated with variation in the processing of aversive stimuli and widely studied as risk factors for psychiatric disorders. We show that variants at the serotonin transporter gene (SLC6A4) and serotonin 2A receptor gene (HTR2A) predict contributions to the public good in economic games, dependent upon whether contribution behavior can be punished. Participants with a variant at the serotonin transporter gene contribute more, leading to group-level differences in cooperation, but this effect dissipates in the presence of punishment. When contribution behavior can be punished, those with a variant at the serotonin 2A receptor gene contribute more than those without it. This variant also predicts a more stressful experience of the games. The diversity of institutions (including norms) that govern cooperation and punishment may create selective pressures for punishment avoidance that change rapidly across time and space. Variant-specific epigenetic regulation of these genes, as well as population-level variation in the frequencies of these variants, may facilitate adaptation to local norms of cooperation and punishment.
authors: Centre for Behavior and Evolution, Institute of Neuroscience, Newcastle University, Newcastle Upon Tyne NE2 4HH, United Kingdom. kbschroeder@ucdavis.edu
authors: Kari B
authors: KB
authors: Schroeder
authors: Richard
authors: R
authors: McElreath
authors: Daniel
authors: D
authors: Nettle
mesh_terms: D003299:Cooperative Behavior; D019143:Evolution, Molecular; D005260:Female; D005716:Game Theory; D014644:Genetic Variation; D006239:Haplotypes; D006801:Humans; D008297:Male; D018803:Models, Economic; D008960:Models, Psychological; D011678:Punishment / Q000523:psychology*; D044402:Receptor, Serotonin, 5-HT2A / Q000235:genetics*; D050486:Serotonin Plasma Membrane Transport Proteins / Q000235:genetics*; D055815:Young Adult
chemical_list: D044402:Receptor, Serotonin, 5-HT2A; C493230:SLC6A4 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins