Sometimes a facial expression is worth a thousand words, and scientists have identified one in particular that might have helped to evolve all the words.
"Not Face", as it's referred to in the scientific journal Cognition, is basically the emoji whose mouth is a straight, solemn line, the one that strikes the perfect balance between a smile and a frown. It's the face you make when your friend hooks up with their ex — again — or when your uncle starts talking politics during Thanksgiving dinner.
But according to the study's co-author Aleix Martinez, the face is much more than an expression that could be interpreted as snark. It might have also acted as a signifier to early speakers, like a question mark might have been, that something they'd just communicated didn't make sense.
"A grammatical marker is a sound or facial expression or sign that has some grammatical function, and these things distinguish animal communication from human language," Martinez told The Washington Post.
The 158 speakers that Martinez studied were native speakers of English, Mandarin, Spanish and American Sign Language. All of the subjects communicating with spoken languages employed the use of the "Not Face" but, interestingly, so did those who used ASL.
The non-verbal communicators' use of the expression reinforced the idea that the "Not Face" did in fact evolve as a part of language in and of itself — and now, scientists are hunting for the way facial expressions and verbal communication work in tandem to create uniquely human speech.