What’s in a smile

His head tilted, the guitarist tickled the strings and the other clapped, chirped and warbled. They slowed as a small girl strode into the arena wearing a tight, colourful dress. A staccato of feet and she commanded the stage and the viewers’ attention. Her hair was oiled and scraped back, face locked in concentration, she battered the boards. Thrusting her hips forward; spinning, scolding, then inviting. We feared the wooden platform would give way under the dancer´s energy but it held firm as she hovered in a display that defied gravity. We too, were sweating when she threw her arms into the air and her features finally relaxed into a broad grin. We took to our feet, smiling back among roars of applause.

A flamenco show, a whispered joke, a warm embrace, the emotion seethes to our brain tickling the left anterior temporal region which fires impulses to our face where two muscles stir into action. The zygomatic major which lies along the cheek pulls our lips upwards and the orbicularis oculi muscle encircling the eye socket lifts our brows and squeezes the corners of our eyes. The entire process lasts between one and four seconds.

Other muscles can mimic a smile but only this intimate tango produces the expression known as a “Duchenne smile”. Named after the French anatomist Guillaume Duchenne, it is an indicator of positive emotion. He honed his theories in the nineteenth century by shocking the heads of executed criminals. Although a smile can reflect various emotions, including embarrassment, deceit, and grief, Duchenne noted that the eyes held the secret to expressing true joy.

Since then, our understanding of the smile has raised more eyebrows. We now know that the intensity of a grin can predict marital and personal happiness, and maybe even how long we´ll live. The saying that “a smile is a window to the soul” rings true for researchers at the University of California who analysed the college yearbook photos of women. They followed their personal lives for the next 30 years and discovered those women who had more Duchenne-like expressions in their photo at 21 years old also had higher levels of wellbeing and marital satisfaction at 52. Another study that rated the smiles of baseball players from photos taken in 1952 concluded that those with positive smiles were half as likely to have died that those who didn´t.

Mental health experts have also noticed that wherever positive emotions go, «Duchenne» smiles follow. Patients with depression displayed such smiles more on release interviews than during their admissions; the patient´s smiling also increased throughout therapy as their condition improved.

The universality of smiling and that we begin so young has lead to the conclusion that this particular human expression has more to do with evolution than culture. Therefore, it comes as no surprise that newborns can accurately display and interpret facial expressions. At just 10 months, for instance, an infant will offer a false smile to a stranger while reserving a genuine, «Duchenne» smile for its mother. Other studies showed that when mothers faked depression, infants shook their tiny fists in distress while after just 3 minutes of smile-free interaction they became withdrawn.

Infants as young as 10 months know the value of a smile.
Science has identified possible reasons why we find a smile attractive. MRI scans of subjects viewing pretty faces have shown activity in the part of the brain that produces sensory rewards. The activity increased when a smile was added to the mix. So, not only, does a smile make us more attractive to others it helps us feel better about ourselves. So Quesada Dental hopes you´ll all be soon smiling and remember the words of Louis Armstrong, “the whole world smiles with you”.


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