DAVID GREENE, HOST:
And, you know, all over the world people say they make friends by breaking bread together. There's this assumption that when you sit down to eat with one another, you become closer. Well, let's talk about that with NPR social science correspondent Shankar Vedantam, who is going to break bread with me. Hey, Shankar.
SHANKAR VEDANTAM, BYLINE: (Laughter) Hi, David. How are you?
GREENE: We've broken bread. We're already friends.
GREENE: Well, so what's this research you're looking at?