The original form is the contagion of fear and alarm. You're in a flock of birds. One bird suddenly takes off. You have no time to wait and see what's going on. You take off, too. Otherwise, you're lunch.

If there is any form of contagion that is adaptive, it is the immediate response to the fear of others. If others are fearful, there may be good reason for you to be fearful too.

If one bird foraging in a flock on the ground suddenly takes off, all other birds will take off immediately after, before they even know what's going on. The one who stays behind may be prey.

Religion may have become a codification of morality, and it may fortify it, but it's not the origin of it.

Bonobo studies started in the '70s and came to fruition in the '80s. Then in the '90s, all of a sudden, boom, they ended because of the warfare in the Congo. It was really bad for the bonobo and ironic that people with their warfare were preventing us from studying the hippies of the primate world.

The whole reason people fill their homes with furry carnivores and not with, say, iguanas and turtles, is because mammals offer something no reptile ever will. They give affection, they want affection, and respond to our emotions the way we do to theirs.