Prometheus 6

Interestingly, the research team also had their subjects fill out a questionnaire to determine their degree of Machiavellian behavior. Those who proved to be the most ruthless of the bunch offered little to nothing when there was no threat of punishment, but within the punishment paradigm, they were generous enough to stave off retribution.

"These are socially intelligent, selfish people," Fehr says about the more calculating subjects. "They escape the punishments that are inherent in social interactions, because they seem to have a fine sense of when punishment is in the air."

Crime and Punishment: Why Do We Conform to Society?

A pair of brain regions work together to assess the threat of punishment and override our selfish tendencies