How the Universal 'Anger Face' Evolved in Humans

The expression of anger is universal--the lowered brow, the flared nostrils, the thinned lips. Now, scientists have taken a closer look at this "anger face" and have found out what factors contributed to its evolution.

"The expression is cross-culturally universal, and even congenitally blind children make this same face without ever having seen one," said Aaron Sell, one of the researchers, in a news release. "Our earlier research showed that anger evolved to motivate effective bargaining behavior during conflicts of interest."

The more harm an individual can inflict on another, the more bargaining power he or she wields. This means that looking menacing can up a person's bargaining power. In fact, earlier work has shown that stronger men anger more easily, fight more often, feel entitled to more unequal treatment, resolve conflicts more in their own favor and are more in favor of military solutions. Going off of this, the researchers hypothesized that an "anger face" should make a person appear physically stronger.

The scientists used computer-generated faces in order to demonstrate that each of the individual components of the anger face made people appear physically stronger. For example, while the lowered brow is a component of the anger face, it doesn't make a face look angry in and of itself. Yet when images of faces with a lowered brow and non-lowered brow were shown to volunteers, subjects reported that the face with the lowered brow belonged to a physically stronger person.

"Our previous research showed that humans are exceptionally good at assessing fighting ability just by looking at someone's face," said Sell. "Since people who are judged to be stronger tend to get their way more often, other things being equal, the researchers concluded that the explanation for evolution of the form of the human angry face is surprisingly simple-it is a threat display."

The findings reveal a little bit more about how the anger face evolved and shows how the function of the face is intimidation. It therefore makes sense that evolution selected this particular facial display to correspond with anger.

The findings are published in the journal Evolution and Human Behavior.