Need For Enhanced Cues Of Strength Led To Evolution Of Universal Angry Face

Chuck Bednar for – Your Universe Online
Regardless of age, race, gender or nationality, all people make the same facial expression when they’re angry, experts from the University of California, Santa Barbara (UCSB) and Australia’s Griffith University report in the latest online edition of Evolution and Human Behavior.
The study authors call it the universal “anger face,” noting that it is characterized by a lowered brow, a thinning of the lips and a flaring of the nostrils. In their research, they identified the functional advantages that caused this particular expression to evolve and become what they call “part of our basic biology as humans.”
“Each element is designed to help intimidate others by making the angry individual appear more capable of delivering harm if not appeased,” said co-author Dr. Aaron Sell, a lecturer at Griffith University who was previously a postdoctoral scholar at UCSB’s Center for Evolutionary Psychology, according to the Huffington Post. “The expression is cross-culturally universal, and even congenitally blind children make this same face without ever having seen one.”
The research, which is part of a larger analysis of the evolutionary function of anger, discovered that the expression uses seven distinct muscle groups that contract in a highly stereotyped manner. Dr. Sell’s team set out to discover exactly why evolution selected these specific muscular contractions to depict the emotion.
He and his colleagues showed 141 men and women different computer images of a male face, some of which had been altered to include one of the key facial features linked to anger, said Huffington Post reporter Jacqueline Howard. The manipulated photos were shown next to the original untouched version, and study participants were asked to select which image made the man depicted appear to be physically stronger.
With just one slight change, such as a lowered brow, neither of the faces appeared to be angry, the researchers said according to Daily Mail reporter Mark Prigg. However, when both faces were shown to a subject, that person indicated that the face with the lowered brow looked like it belonged to a physically stronger man.
“The experiment was repeated one-by-one with each of the other major components of the classic anger face – raised cheekbones (as in a snarl), lips thinned and pushed out, the mouth raised (as in defiance), the nose flared and the chin pushed out and up,” Prigg explained. “As predicted, the presence by itself of any one of these muscle contractions led observers to judge that the person making the face was physically stronger.”
“Our previous research showed that humans are exceptionally good at assessing fighting ability just by looking at someone’s face,” Dr. Sell said in a recent statement. “Since people who are judged to be stronger tend to get their way more often, other things being equal, we concluded that the explanation for evolution of the form of the human anger face is surprisingly simple – it is a threat display.”
These threat displays are similar to those used by other animals for self-preservation and protection purposes and consist of cues to exaggerate fighting ability, the researchers said. Since study participants consistently rated faces containing even one of these muscle movements as belonging to a physically stronger person, the findings support the notion that this universal anger face evolved in order to enhance cues of strength.
“This makes sense of why evolution selected this particular facial display to co-occur with the onset of anger,” said co-author and UCSB professor of anthropology John Tooby. “Anger is triggered by the refusal to accept the situation, and the face immediately organizes itself to advertise to the other party the costs of not making the situation more acceptable. What is most pleasing about these results is that no feature of the anger face appears to be arbitrary; they all deliver the same message.”
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