About one in every 100 people doesn’t care what others think of him. These people are hard to spot. They are usually physically healthy, and their intelligence is often above average. Yet, in the words of one psychiatrist, they lie without compunction, cheat, steal, and casually violate any and all norms of social conduct whenever it suits their whim. They have no concern for others’ suffering, no remorse when caught, and punishment does little to change them. They are called psychopaths.
Mental-health professionals have usually treated psychopathic behavior as a disorder — a large proportion of the prison population, after all, has been diagnosed with some version of the trait. But viewed from an evolutionary angle, psychopathy looks more like a feature than a bug. Most people are cooperative, trusting and generous. This pays off in the long term. It also creates an opening for those who would rather prey on society than join it. A psychopath’s deceitful, manipulative, and callous nature equips him (it’s several times more likely to be a “him”) to fill this niche.
Psychopaths’ deficit is in empathy, not reason. They understand morality, but they are immune to other people’s emotions. There aren’t many openings for psychopaths, because if there were lots of them, there would be no society to plunder.
The benefit of psychopathy is that you exploit the altruistic without the cost of reciprocating. The downside is that you can cheat a person only so many times. Your victims will also warn their friends about you, and they may seek revenge. So a psychopath must stay one step ahead of his reputation.