we may have paid the price for this altruism with our darker side: our instinct to punish those who we deem to be moral violators; our reflexive delineation of people into good and evil; our desperation to conform to our in-group and the ease with which we demonize those in the out-group. And with these new traits, empowered by our newly enlarged brains and cumulative language, the human instinct for politics—derived from our ancestral primates—was no longer a little trick for climbing social hierarchies but a cudgel of coordinated conquest.
