Some things are funny—jokes, puns, sitcoms, Charlie Chaplin, The Far Side, Malvolio with his yellow garters crossed—but why? Why does humor exist in the first place? Why do we spend so much of our time passing on amusing anecdotes, making wisecracks, watching The Simpsons? In Inside Jokes, Matthew Hurley, Daniel Dennett, and Reginald Adams offer an evolutionary and cognitive perspective. Humor, they propose, evolved out of a computational problem that arose when our long-ago ancestors were furnished with open-ended thinking.