The author looks at the role of reciprocal altruism and of "cheating" and cheater detection and indicates they exert pressure for the selection on moral outrage. Moral outrage leads to the desire to punish, which serves an expiatory role. Punishment can be tempered with mercy by tapping into the evolved emotions of empathy and sympathy as cultural ideas defining all human beings as intrinsically valuable. Reconciliation and reintegration, as contained in restorative justice, are also examined from this naturalistic perspective. The author considers how cultural variability can be accommodated and concludes evolutionary psychology may provide an encompassing theoretical perspective of justice. 74 references