A surplus of men leads to violence, right? It depends on how you look at it, say anthropologists Ryan Schacht, Kristin Rauch and Monique Borgerhoff Mulder.
In Asia there are 100 million more men than women and this excess of men, particularly in China, has led to fears of "macho militarism and imperialism". These concerns portray a violent, socially unstable world, caused by a glut of testosterone-driven, unmarried men. But although it is generally true that men are more violence-prone than women, does it follow that an abundance of men will cause an abundance of violence?