Psychologist Paul Ekman can read minds just by studying fleeting expressions on faces. He has taught police and intelligence officers across North America and Europe to do the same. Ekman learned his skill in part from the culturally isolated South Fore people of New Guinea 40 years ago, when he began a photographic investigation of nature versus nurture. If facial reactions are learned, he reasoned, theirs should be unique. Instead, he found that the Fore’s expressions of emotions from joy to anger mirrored those of other cultures. Ekman’s photographs, which made plausible the once-contentious idea of universal human expressions, are on display at the Exploratorium in San Francisco through April 27. Can you relate to New Guinea’s grins and glares?