Science Of Smile

Interview with Marianne LaFrance, author of the new book Lip Service: Smiles in Life, Death, Trust, Lies, Work, Memory, Sex, and Politics:

Wired.com: Are many muscles involved in smiling?

LaFrance: Two, the obicularis occuli and zygomaticus major, are the primary muscles involved in the so-called genuine smile. But the so-called mouth smile can co-occur with a number of other muscles on the face at the same time. So the mouth may be smiling but the brows could be showing anger, the eyes could be showing surprise or fear, the upper lip could be showing contempt, the nose could be showing some disgust. So the smile is interesting to those of us who study it because it’s not just one thing. It’s multiple and complicated. Even the temporal pattern is important. Genuine smiles tend to come on the face relatively languidly and go off the face in the same kind of way. Fake smiles often seem to snap on the face and snap off.

Wired.com: Humans have always been captivated by smiles. When did smile science get its real start?

LaFrance: In the late 1800s Charles Darwin published his famous book The Expression of Emotions in Man and Animals. He devoted some time to smiling, but was more interested in other facial expressions. His colleague across the channel, Guillaume-Benjamin Duchenne, was doing experiments where he would zap single muscles on the face with electricity and then look at the changes. His primary distinction was between smiles that came from the soul, non-deliberate smiles, and the ones put there consciously. That’s why people who study smiles call the spontaneous smile the Duchenne smile.

Wired.com: Did you come across anything surprising while researching this book?

LaFrance: I found that in obituaries people often, more than any other attribute, mentioned their loved one’s smile. Why is it that, after a person is dead, they are described as someone with a smile? It is one more indicator that smiling is a way we connect with other people, in a way that can be easy to underestimate, but in fact I don’t think its importance can be underestimated.