h their bodies to prevent a school shooter from entering (Rand & Epstein, 2014). This is often seen as evidence for a role of group selection (Fehr & Fischbacher, 2003). However, an alternate explanation is that we do not consider the likelihood of reciprocation (Hoffman et al., 2015), as described above. To

erate in contexts where there is no possibility of reciprocation, such as in one-shot anonymous laboratory experiments like the dictator game (Fehr & Fischbacher, 2003), as well as when performing heroic and dangerous acts. Consider soldiers who throw themselves on a grenade to save their compatriots or storie

Gilbert, D. T. (2008). The paradoxical consequences of revenge. Journal of Personality and Social Psychology, 95 (6), 1316-1324; de Quervain, D.J-F., Fischbacher, U, Treyer, V., Schellhammer, M., Schnyder, U., Buck, A., & Fehr, E. (2004). The neural basis of altruistic punishment. Science, 305, 1254-1258; Fehr

ess; 1939. Rilling J, Gutman D, Zeh T, Pagnoni G, Berns G, Kilts C. A Neural Basis for Social Cooperation. Neuron 2002;35:395-504. De Quervain DJF, Fischbacher U, Treyer V, Schellhammer M, Schnyder U, Buck A, Fehr E. The Neural Basis of Altruistic Punishment. Science 2004;305:1254-8. Eisenberger NI, Lieberm