“Most men are not criminals, of course, but a huge majority of criminals are men. Men make up 93 percent of the American prison population, and young men die from accidents and violence at up to six times the rate of young women. The cause is not just poor socialization, however: Male violence is a problem across all societies, communities, and races, and the primary driver is testosterone, which declines steadily throughout a man’s adult lifetime. As testosterone levels go down, so do rates of violence and accidental death — which would not be the case if socialization alone were to blame.”