Everyone smiles in the same language, right? For decades, psychologists have backed up the idea that facial expressions are universal. Paul Ekman’s research in the 1960s was a driving force behind this popular notion. He found cultures worldwide describe facial expressions the same way: For example, a scrunched-up nose signals disgust. Even in the isolated Fore tribe of Papua New Guinea, Ekman’s theory held up. But other researchers believe subtle differences in facial expressions ex…