On December 7, Robert Provine, professor of psychology, discussed laughter and why tragedy sometimes makes us laugh on NPR’s “Science Friday.” He was joined on the show by comedian Tig Notaro, who incorporated her breast cancer diagnosis into her stand-up routine. “We humans, in many ways, are beasts of the herd. We are not the rational, voluntary beings we fashion ourselves as,” Provine said. “The essential ingredient for laughter is another person,” Provine said. “In Tig’s audience, you had a group of people, and they’re laughing when they hear other people laugh. So laughter is contagious. Also, it was a comedy …