Slate begins a series on creative pairs: Two is the Magic Number.
The sensation of “mirror neurons” helped further dissolve the distinction. About 10 years ago, a team of Italian researchers showed that certain neurons that fire during actions by macaque monkeys—when they pick up a peanut, for example—also fire when they watch someone else pick up the peanut. It’s probably overblown to say—as many have—that this phenomenon can explain everything from empathy and altruism to the evolution of human culture. But the point is that our brains register individual and social experience in tandem.