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It's 7 AM, and Susan Jenks, a mother of two, would love more sleep, but she can hear her five-month-old son, Angus, rousing in the next room. "I'm hardly able to drag myself out of bed," says Jenks, who, with both an infant and an oldre son age two, is no stranger to fatigue. "But when I look into his crib, and he gives me a big smile, it fills me with joy - and then everything is fine."
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Such is the power of a simple smile. In fact, research over the last two decades has been proving scientifically what aphorisms and popular song lyrics have espoused for eons: Smile, and the whole world smiles with you, and grey skies really will clear up if you put on a happy face.
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"A smile is central to our evolution and one of the most powerful tools of human behaviour," says Dacher Keltner, a professor of psychology at the University of California, who has studied the importance of facial expression - including the variety and impact of smiles.
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Anyone who has been around a smiling baby knows how a spontaneous grin helps build kinship, strengthen social bonds and release positive brain chemicals that help us feel good. Standing at a grocery checkout with her sparkly Angus, Jenks is apt to hear a chorus of oohs and aahs as her baby uses his new-found power of smiling to elicit smiles from others.
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CHILD-DEVELOPMENT experts call that positive exchange between infant and adult the "interactional dance," which emerges as the baby's brain develops higher functioning. "A mother and baby exchange smiles in a rhythmic and synchronized way that is important for the development of attachment and intellectual development," says Ulrich Mueller, a professor of psychology specializing in child development. Mueller says studies have found that if a parent responds to a baby's smile with an expressionless face, the infant gets upset. "This indicates how important the caregiver's smile is for the infant," says Mueller, adding that infants of depressed mothers show fewer signs of happiness and smile less often than infants of nondepressed mothers.
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In 1872 Charles Darwin proposed in his book, The Expression of Emotion in Man and Animals, that facial expressions are biologically based and universal among humans and therefore must provide an evolutionary advantage such as building kinship bonds, improving co-operation and helping increase the survival of the species. However, the celebrated anthropologist Margaret Mead thought the smile was a cultural behaviour that varied between societies.
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It wasn't until the 1960s that psychologist Paul Ekman decided to settle the argument. He travelled the world, showing pictures of facial expressions to people of different cultures and found that, even in the remote jungles of Papua New Guinea, expressions like a joyful smile had the same emotional meaning. Ekman and a colleague, Wallace Friesen, then spent eight years creating a reliable way to describe and replicate facial movements so researchers could more scientifically study facial expression and emotion. They systematically categorized 43 separate muscle movements of the face and their more than 3000 meaningful combinations, calling their system the Facial Action Coding System, or FACS.
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"FACS revolutionized the study of facial expression and human emotion,: says Keltner, who did his postgraduate work in Ekman's lab. "It gave researchers an objective language to answer how emotions are mapped onto our face and our nervous systems." Now, with FACS as the base, 18 types of smiles have been identified, such as shy, embarrassed, sarcastic and loving. But the two types that have received the most research attention are the spontaneous joyful smile and the fake smile. The first, also called the Duchenne smile after the 19th-century. French neurologist who first described it, involves two sets of muscles. One pulls back the corners of the mouth and raises the cheeks high, and the other make the eyes crinke. Scientists have discovered that a genuine Duchenne smile is a marker of real happiness. The fake smile - sometimes called the fight-attendant smile-uses only the frist muscle set and is generally used as a form of courtesy.
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In one of his most famous studies, Keltner and colleague LeeAnne Harker coded the smiles of 114 women who posed for their college yearbook photo in 1958 and 1960. All but three smiled, but 61 did the fake courtesy smile, and 50 had Duchenne smiles. Keltner's study found that over 30 years of follow-up, the women who displayed Duchenne smiles were more apt to get married and remain married, and scored higher on tests of emotional and physical well-being. Other Keltner studies have found that people who display spontaneous, real smiles are better able to overcome stressful events such as the death of a spouse, and that couples who show loving smiles when talking about each other release oxytocin-called the caring hormone and association with bonding and reproduction-into the blood.
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Keltner notes that while some people are born with happier temperaments, which set them up for success, others can become happier by being taught how to cultivate a genuine smile. "In the happiness literature," says Keltner, "the greatest association with happiness is connection to others. Teaching smiling is important because it helps us connect."
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Putting on a happy face not only helps us make friends, it translates into altered brain chemistry that makes us feel better. Ekman and University of Wisconsin neuroscientist Richard Davidson used brain scans to show that the Duchenne smile activates some parts of the brain associated with pleasure and happiness, though it does not activate the full pattern associated with these emotions. They found that if people learned how to activate the muscles of the Duchenne smile, even artificially, they could produce similar brain activity.
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Since smiling is so imporant to happiness and social connection, losing one's smile is devastating. Twice in his adult life Ross Main, who operates a guest house in Canada, has had half his face paralyzed by Bell's palsy, a disorder in which the seventh cranial nerve becomes inflamed, probably from a viral infection. " I could only smile with half my face, and the result was this weird grimace," says Main, an outgoing person who became self-conscious and reluctant to go out or meet people. "You don't realize how essential a smile is until you can't do it."
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Main was lucky: Both times his smile returned within three or four weeks. But about 15 percent of those with Bell's palsy never get their smiles back fully. Others lose their smiles through cancer, stroke or injury. Some people, such as those with a facial disorder called Moebius syndrome, are born without a normal smile.
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"My patients have taught me the value of smiling," says Dr Ralph Manktelow, a plastic surgeon. "They say, 'Because I can't smile, people think I am unfriendly, sad, angry or depressed, and I can't show them what I am really like." A smile is a powerful part of our conversation capability. If you can't smile, you are very limited in your ability to pass on information and relate to other people."
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Manktelow and paediatric plastic surgeon Dr Ronald Zuker, co-head world-renowned Facial Paralysis Team in Toronto, Canada, which specializes in the reconstruction of missing or paralyzed smiles. About 150 patients a year, some 50 of them children, come from around the world with facial paralysis. About of these patients are suitable for the microsurgical procedure, in which surgeons transfer a piece of muscle from the leg to the face. The surgeons attach a nerve to the muscle to make it contract and provide a smile movement. The nerve comes from either the facial nerve on the opposite side of the face or a nerve that normally controls biting. After up to a year of nerve growth, patients develop a smile. If the biting nerve was used, patients first learn to smile by biting.
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"With time and practice most learn to smile without biting, and many smile without biting, and many smile without even thinking about it," says Manktelow. "The smile is so important it appears that the brain learns to control the movement of the muscles, and the smile centre takes over to create a spontaneous smile."
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For Zuker, one of the great rewards of his work is to get a thank-you letter - with a picture. "There is nothing better than to see a child you've operated on-holding a bat on his shoulder or in a family photo - with a great big smile on his face."
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