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The next time you get really mad, take a look in the mirror. See the lowered brow, the thinned lips and the flared nostrils? That's what social scientists call the "anger face," and it appears to be part of our basic biology as humans.
Now, researchers at UC Santa Barbara and at Griffith University in Australia have identified the functional advantages that caused the specific appearance of the anger face to evolve. Their findings appear in the current online edition of the journal Evolution and Human Behavior.
"The expression is
cross-culturally universal, and even congenitally blind children make this same
face without ever having seen one," said lead author Aaron Sell, a
lecturer at the School of Criminology at Griffith University in Australia. Sell
was formerly a postdoctoral scholar at UCSB's Center for Evolutionary
Psychology.
The anger expression
employs seven distinct muscle groups that contract in a highly stereotyped
manner. The researchers sought to understand why evolution chose those
particular muscle contractions to signal the emotional state of anger.
The greater the harm an
individual can inflict, noted Leda Cosmides, the more bargaining power he or
she wields. Cosmides, professor of psychology at UCSB, is a co-author on the
study along with John Tooby, UCSB professor of anthropology. Cosmides and Tooby
are co-directors of the campus's Center for Evolutionary Psychology.
"This general
bargaining-through-menace principle applies to humans as well," said
Tooby. "In earlier work we were able to confirm the predictions that
stronger men anger more easily, fight more often, feel entitled to more unequal
treatment, resolve conflicts more in their own favor and are even more in favor
of military solutions than are physically weak men."
Starting from the
hypothesis that anger is a bargaining emotion, the researchers reasoned that
the first step is communicating to the other party that the anger-triggering
event is not acceptable, and the conflict will not end until an implicit
agreement is reached. This, they say, is why the emotion of anger has a facial
expression associated with it.
"But the anger face not only signals the
onset of a conflict," said Sell. "Any distinctive facial display
could do that. We hypothesized that the anger face evolved its specific form
because it delivers something more for the expresser: Each element is designed
to help intimidate others by making the angry individual appear more capable of
delivering harm if not appeased."
For our ancestors,
Cosmides noted, greater upper body strength led to a greater ability to inflict
harm; so the hypothesis was that the anger face should make a person appear
stronger.
Using
computer-generated faces, the researchers demonstrated that each of the
individual components of the anger face made those computer-generated people
appear physically stronger.
For example, the most common feature of the anger
face is the lowered brow. Researchers took a computerized image of an average
human face and then digitally morphed it in two ways: One photo showed a
lowered brow, and the other a raised brow. "With just this one difference,
neither face appeared 'angry,' " said Sell. "But when these two faces
were shown to subjects, they reported the lowered brow face as looking 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. 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," 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 anger face is surprisingly simple -- it is a threat
display."
These threat displays
-- like those of other animals -- consist of exaggerations of cues of fighting
ability, Sell continued. "So a man will puff up his chest, stand tall and
morph his face to make himself appear stronger.
"The function of
the anger face is intimidation," added Cosmides, "just like a frog
will puff itself up or a baboon will display its canines."
As Tooby explained,
"This makes sense of why evolution selected this particular facial display
to co-occur with the onset of anger. 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."
According to Sell, the
researchers know this to be true because each of the seven components has the
same effect. "In the final analysis, you can think of the anger face as a
constellation of features, each of which makes you appear physically more
formidable."
Story Source:
The above story is
based on materials provided
by University of California - Santa Barbara.
The original article was written by Andrea Estrada. Note: Materials may be edited for
content and length.
Journal
Reference:
1.
Aaron Sell, Leda Cosmides, John Tooby. The human anger face evolved
to enhance cues of strength. Evolution
and Human Behavior, 2014; 35 (5): 425 DOI: 10.1016/j.evolhumbehav.2014.05.008
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