Beginning to explain it means questioning the assumption that you have to explain humor: “Laughter, a topic that stymied philosophers for 2,000 years, is finally yielding to science. Researchers have scanned brains and tickled babies, chimpanzees and rats. They’ve traced the evolution of laughter back to what looks like the primal joke — or, to be precise, the first stand-up routine to kill with an audience of primates.” (New York Times )