The universal “anger face” — thinned lips, lowered eyebrows and flared nostrils — appears to be a part of our basic biology.

Researchers at Griffith University in Australia and UC Santa Barbara have discovered the functional benefits that result in the unique appearance of the anger face.

The expression of anger involves seven specific muscle groups that contract in a conventional manner. Why evolution involved these specific muscle contractions to prompt the emotional state of anger is what the researchers sought to understand.

Lead study author Aaron Sell, a lecturer at the School of Criminology at Griffith University in Australia, and colleagues hypothesized that anger is a bargaining emotion. The first step is communicating to the other person that the event triggering the anger is not fair nor appreciated, and any conflict that ensues will not be worked out until an agreement is established. The researchers say this why a specific facial expression is linked to the emotion of anger.

“The anger face not only signals the onset of a conflict. 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,” said Sell in a statement.

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