Wired to Weep Together

In the early 1990s, neuroscientist Giacomo Rizzolatti and his team at the University of Parma were studying motor neurons in macaque monkeys when they stumbled onto something extraordinary. A monkey sat perfectly still while a researcher reached over and picked up a peanut. Suddenly, the monkey's motor neurons fired — the same neurons that would have activated if the monkey itself had grabbed the peanut.…