New research could explain why some comedians are funnier when you're surrounded by laughing people instead of sitting by yourself.

In a new study, researchers found that the brain appears to prime itself for laughter when it hears someone laughing:
But why?
Elsewhere in this week's Bodyhack:
WHO (are those dead people in "Casino Royale")
WHAT (is a researcher doing with psychotic Americans)
WHERE (you can lose sensation if you ride a bike and happen to be female)
WHEN (will mice live longer)
WHY (Indians don't fit into condoms)
HOW (your beer belly might fuel the world.)