Faces say so much that Google’s Gmail includes more than 20 emoticons :) to make up for the personal touches that e-mail lacks. But those basic expressions, so important in conversation, didn’t originate for the sake of communication, psychologists say.
At least two emotional expressions, those of fear and disgust, first served to moderate sensations coming in from the outside world, researchers report online June 15 in Nature Neuroscience. They show that terrified eyes widen and nostrils flare to monitor the surroundings, and the nose crinkles in disgust to impede nasty odors.
Darwin hypothesized that facial expressions originally had just such a use in his overlooked book The Expression of the Emotions in Man and Animals. He thought faces once acted to protect the beholder, like a flexible shield between the atmosphere and sensory receptors within the eyes, nose, mouth and ears. Yet until now, that idea hadn’t been tested and most people believe that expressions have always been just a way to communicate, says Adam Anderson, a cognitive neuroscientist at the University of Toronto who led the study.
“Their finding is exactly what Darwin predicted in 1872,” says Paul Ekman, a psychologist at the University of California, San Francisco.
Researchers measured the field of vision for study participants who pretended to be freaked out or grossed out. When participants put on a fearful face, their eyes widened and they were able to detect lights flashing above their head. When acting disgusted, they squinted and couldn’t see the flashing lights. Using MRI, the researchers measured how much air the participants inhaled under each facial condition. Air intake increased when people wore a fearful expression and decreased when they looked revolted. The results support the idea that fearful faces observe more of the surrounding atmosphere — by seeing farther and sniffing deeper, the researchers say. In contrast, disgusted faces block the senses from detecting the environment.
As communication arose in groups, facial expressions might have acquired a second, more vital role in sending signals to others, the researchers suggest. They reason that if expressions had originated for communication, expressions should be as variable as language.
“The word for anger is not the same in Russian and in English, but the expression is,” agrees Ekman, who has spent decades documenting the similarity between facial expressions from more than 30 cultures.
Once expressions began to get noticed by neighbors in a group, copying those expressions would have helped others survive by the same means. A terrified gaze from one person signals that others nearby should open their eyes to monitor the environment, says Paul Whalen, a neuroscientist at Dartmouth who studies how the brain responds to others’ facial expressions.
Today, reflecting another’s expression is hardwired to some degree. Anderson says he remembers that when a classmate vomited in his kindergarten class, he gagged too. And Anderson’s graduate student, Joshua Susskind, admits that while he analyzed videos taken for the study, he caught himself unconsciously mimicking the faces he saw on the screen.
The original functions of other nonverbal expressions remain elusive, Ekman says, noting that Darwin didn’t even touch on the smile.