In the 1960s, many scholars believed that people learned to express emotions by observing others—a theory advanced by such famous anthropologists as Margaret Mead, PhD, and Gregory Bateson, PhD. But in 1967, upstart psychologist Paul Ekman, PhD, went to New Guinea with camera in hand and struck a fatal blow to that idea.

Ekman traveled to the remote island in search of the South Fore people, most of whom had had no contact with the outside world. If he could record their facial expressions and show that they were similar to ours, Ekman believed it would suggest that frowns and smiles—rather than being culturally learned—are universal and inborn.

And that's exactly what Ekman did, publishing his results in Science (Vol. 164, No. 3,875, pages 86–88) and the Journal for Social and Personality (Vol. 17, No. 2, pages 124–129.)

"I knew...that soon there would be no isolated cultures left in the world, and, indeed, two years after I was there, magazine photographers came in," says Ekman, now an emeritus psychology professor at the University of California Medical School in San Francisco. "I got there just in time, and I was able to get pretty decisive evidence."

In celebration of the 40th anniversary of his trip to New Guinea, Ekman will give a talk at the San Francisco Exploratorium on Jan. 26, where he'll share videos and stories from his adventure. Ekman's photographs will also be on display at the museum Jan. 22 through April 27.