"Michael Ryan synthesizes an absolutely incredible amount of information to arrive at a provocative conclusion regarding the difference between rightists and leftists." -- John R. Hibbing, University of Nebraska-Lincoln, USA"This important book is a sparklingly original natural history of the age-old conflict between left and right." -- Richard Wrangham, Harvard University, USA"Do liberal forms of cooperation and pacifism and conservative forms of competition and authoritarianism have deep origins in our evolutionary history? In prose that is skilled and accessible, Michael P. Ryan makes a passionate, provocative argument that they do. He has read seemingly everything, and he pulls no punches. His book provides food for thought, worry, and, surprisingly, hope." -- John T. Jost, New York University, USA