Researchers said that the "anger face", the face people made when they get angry, were part of human's basic biology.

Aaron Sell from University of California (UC) said that even blind children have the same face expression to getting angry even if they haven't seen one.

He explained that their earlier researched showed the anger can motivate certain behaviors that sprung from conflicts of interest.

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Leda Cosmides, one of the UC researchers, said that the greater the harm a person could do the more strength he or she uses.

"Earlier research showed that stronger men tend to be easily angered, they would fight more often to resolve conflicts for their own gain than physically weak men", said John Tooby from UC.

Researchers explained that the anger face is associated with the need to resolve a conflict that was deemed unacceptable by one of the angry parties.

They believe that people make the face expression when they are mad because it is an expression that can intimidate others.

This can also serve as a warning that they could deliver harm if they are not appeased, they added.

Sell explained that previous research showed that humans have the ability to assess fighting ability just by looking at someone's face.

He said that with the idea that stronger people often can get what they want, people use the anger face to look stronger and threaten others.

Cosmides explained the anger face is done for intimidation purposes, like a frog puff up when threatened.

John Tooby, another researcher involved in the study, explained the anger face is meant to advertise that one of the parties refuse to accept the situation that they are facing.

He explained that what is really pleasing is that the anger face delivers the same message to everyone who has seen the expression.