A psychologist explains the evolutionary and psychological roots of laughter, and what an infant’s giggles teach us about how adults bond.

I was sitting in my kitchen one day and made an attempt at being funny, but nobody laughed. My kids began to laugh when I bemoaned that nothing I say is funny. Perhaps ever since we began to emerge ...

Humor has always been subjective. Where some people prefer the physical comedy of Jim Carrey, others may find the dry approach of Albert Brooks preferable. Babies, of course, are not big on subtlety.