Researchers from Ohio State University revealed that there is one particular facial expression that is recognized universally: the "not face," which punctuates negative sentiments. A combination of a furrowed brow, pressed lips and a raised chain, the distinctive face is typically shown in humans when expressing negation, such as disagreeing with a statement or declining a party invitation.

The team made its discovery by filming subjects while they participated in conversations in their native language and subsequently analyzing the videos frame-by-frame in order to pinpoint which facial muscles were moving at specific points in the conversations.

After noticing the "not face," the team discovered that it transcends language; whether subjects were speaking English, Spanish, Mandarin Chinese or American Sign Language (ASL), they used the "not face" to expression negation. Furthermore, the team found that some ASL speakers also used the face in the place of signing the word "not."

Although you might not think of a negative facial expression as connected to language, it can actually act as a grammatical marker that indicates the function of a phrase, thus making it related to the ancient form of communication.

"Grammatical markers are part of the grammar," said Aleix Martinez, senior author on the paper. "The grammar is what defines human language. Other forms of communication are not considered a language because they do not have grammar."

So what's so important about a sour face being connected to language? Scientists believe that the discovery of the "not face" being universal could help them uncover the origins of human language.

"Language (i.e., grammar) is one of the most surprising cognitive abilities of humans," Martinez said. "Almost everything else we have can be traced back through evolution, except language. How's that our closest living relatives do not have it? Do they have some components of it? Primates can communicate nonverbally, is that where language evolved from?"

"Our hypothesis is that facial expressions of emotion (which is a type of nonverbal communication) evolved into grammatical markers (i.e. language)," he added. "This provides a viable evolutionary route for the development of human language."

Martinez claims that the "not face" is a combination of three different facial expressions: anger, disgust and contempt. He believes that this universal face is a window into the evolution of communication and that it likely evolved in early humans.

"Facial expressions are assumed to have evolved for sensory regulation and as a protective mechanism," he said. "For example, disgust is thought to protect us from germs; note it involves closing the mouth, nostrils, and eyes. Anger contracts the muscles of the face, potentially protecting us from punches or in a fall."

However, Martinez adds that as time has passed, these expressions were adapted to respond to "moral" scenarios as opposed to physical, such as responding to an insult or offensive phrase.

The findings were published in the Feb. 9 issue of Cognition.