Why Are You Making That Face?

So why are you making that face? Because back when humans were evolving into what we are now, those specific contortions of eyes, nose, mouth and cheeks were adaptive—that is, useful for surviving.

Have you ever wondered why people the world over make essentially the same face when they’re afraid, whether they’re Maori tribesmen facing a stampede or Wall Street titans being handed a subpoena from the SEC? One explanation for that sameness has been that the expressions arose randomly, but got locked into human nature because other people could understand them: that is, if everyone made the same face for “I’m afraid,” then others in their group could read and understand it instantly—very useful for times before spoken language or when you can’t hear what the other guy might be shouting.

The same reasoning applies to facial expressions of disgust. If your dinner companion makes a face as he tears into his serving of roast boar, it’s helpful to understand it instantly before you, too, chow down on spoiled meat. The sameness of facial expressions is called cultural invariance, and it means that the Maori tribesman can read the hedge fund manager’s expression and the manager can read the tribesman’s.Click here to find out more!

A new study, published online this week in Nature Neuroscience, concludes that facial expressions are not arbitrary symbols whose sole purpose is social communication. In fact, it was Charles Darwin who first suggested that facial expressions have not evolved randomly for the purpose of social communication, and it seems he was right.

Start with the look of different emotions. Fear and disgust expressions have opposite shapes. When you make a fearful face you open your eyes wide and raise your eyebrows and dart your eyes around rapidly while breathing faster. When you’re disgusted you narrow your eyes and lower your brow, keep your eyes more still and slow your air intake. And that, the scientists say, “reflects a fundamental antagonism serving to augment versus diminish sensory exposure.”

The results are precisely what you’d like when you’re either spying a tiger crouched in the brush or smelling a rotting carcass. Making a fearful face enlarges your visual field (good for taking in lots of information about the looming threat and letting you see farther), speeds up your eye movements (good for helping you precisely locate the threat), increases the amount of air you can inhale through your nose (good for getting oxygen to muscles you may need for fight or flight) and speeds up breathing (ditto). Disgust is the opposite: your visual field contracts (sparing you the sight of the disgusting thing), your eye movements slow (same effect), and you inhale less (including of the horrible-smelling trigger of your disgust). A fearful facial expression “may therefore work to enhance perception, whereas disgust dampens it,” scientists led by Joshua Susskind of the University of Toronto report.
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