In the late 1960s, acclaimed psychologist Dr. Paul Ekman began an influential study on human facial expressions. His research among the Fore, an isolated New Guinea tribe with whom the developed world had just made contact—captured the universality of expressions linked to key emotions. This work strongly suggested that emotional facial expressions are biologically determined, as Darwin had predicted. To celebrate the fortieth anniversary of his first expedition, Dr. Ekman and UC Berkeley’s Dr. Robert Levenson discuss emotion research and its implications. The talk includes photographs and never-before-seen footage from Dr. Ekman’s fieldwork.