Humans are among the most altruistic species that we have studied. I know that might sound strange to people who have a strong media diet of all the bad things that people do, but if you put human beings in a lab, they will spontaneously help other people, even strangers, to a degree that you don't see among other species.

Psychopathy in its extreme form affects probably 1% of people, maybe 2%. We all have met somebody who's psychopathic, right? Everybody knows somebody who's like this, and many of us have been burned by them. In fact, most people have been burned by them at least once.

And we know the people who are psychopathic often genuinely don't care about other people at all. It defies logic for there to be such a thing as psychopathy and for humans as a whole to be fundamentally selfish, because we know what truly fundamentally selfish people look like. They look psychopathic.

And if all people were fundamentally selfish,... See more

In addition, very altruistic people seem to be the opposite of people who are psychopathic in terms of their neural structure and function and in some characteristic emotional traits. For example, whereas people who are psychopathic are unusually bad at recognizing when other people are afraid, and we think this is one reason that they're not... See more