An emerging evolutionary perspective suggests that nature and human nature are less "red in tooth and claw" than generally acknowledged by a competition-based view of the biological world. War is not always present in human societies. Peace systems, defined as groups of neighboring societies that do not make war on each other, exist on different continents. A comparison of three peace systems-the Upper Xingu River basin tribes of Brazil, the Iroquois Confederacy of upper New York State, and the European Union-highlight six features hypothesized to be important in the creation and maintenance of intersocietal peace: (i) an overarching social identity, (ii) interconnections among subgroups, (iii) interdependence, (iv) nonwarring values, (v) symbolism and ceremonies that reinforce peace, and (vi) superordinate institutions for conflict management. The existence of peace systems demonstrates that it is possible to create social systems free of war.