Most great apes lived in hierarchical groups, often engaging in fierce battles for position (Boehm, 1999). Even though a few exceptions, like the bonobos, exist today, the main line of our ancestors lived by power and domination. Sometime in the past 2 million years, a remarkable change occurred: The homo evolution moved toward social group living that substantially increased cooperation, joint action, teaching, and learning (Boehm, 2000;Tomasello & Vaish, 2013). Perhaps precursors to empathy helped (de Waal & Preston, 2017), but empathy is reactive and local (Bloom, 2016) and can conflict with fairness and justice (Decety & Cowell, 2015). By itself, empathy does not provide a social organization that can sustain a group's success in the most uncertain and harshest environments. Norms do.Norms are guides to action. They constrain an individual's options in a given context to act in ways that benefit the group, and groups that have a well-functioning norm system function well as groups (Bicchieri, 2006;Chudek & Henrich, 2011;Wilson, 2002). Norms provide organization and regulation of group members' actions that can sustain a group's success even in the face of serious threats-through ice ages, natural catastrophes, and wars.