http://www.wnyc.org/shows/radiolab/episodes/2008/02/22

A friend hooked me up with Radiolab and I’ve been addicted to the show ever since. This episode, about laughter, really tickled me… not because it was funny, but because it asks some serious questions about the behavior.

Example: Baring teeth is an aggressive action in mammals. But smiling for humans is friendly.

Go figure, eh? Odd stuff. Enjoy!