Very interesting panel on Music and brain activity from the World Science Festival with Bobby McFerrin:

I have a feeling that most everyone here at some place inside, they have sincere desire to participate, to become part of something, which is a very strong need in all of us, I think, to be part of some kind of a community and have some kind of a relationship whether it is with another person or music. So, I find very very easily, regardless of what country or culture that I am in, to give an invitation for people to sing and they readily jump on it.

See him in action:

Found through Ribeezie.com