Robert Krulwich delivers the commencement address at College of the Atlantic in Bar Harbor, Maine, on June 2. Jason P. Smith/College of the Atlantic hide caption

itoggle caption Jason P. Smith/College of the Atlantic

Megan Lutz, left, and Justin Chun react to amateur comedian Robert Lynch at the Metropolitan Room in Manhattan, N.Y. Lynch is an anthropologist researching what laughing reveals about us. Melanie Burford for NPR hide caption

itoggle caption Melanie Burford for NPR