Does Smiling Create Happiness? – The Science Behind Your Smile Part 5

“Sometimes your joy is the source of your smile, but sometimes your smile can be the source of your joy.”  – Thich Nhat Hanh

If an authentic (Duchenne) smile is caused by feeling happiness and joy, can smiling alone create these same good emotions in the brain? Paul Ekman joined with Richard Davidson, one of the world’s experts on the neuroscience of emotions, to study what happens in the brain when a persons makes a true smile. Davidson’s work has shown that positive emotions are associated with the activation of the left frontal cortex of the brain, while negative emotions are associated with activation of the right frontal cortex [1, 2]. To study the smile, Ekman and Davidson conducted an experiment with a group of women who watched four short films, two positive (one of puppies playing and one of monkeys playing) and two negative (of an amputation and third-degree burns). Their facial expressions were videotaped while they watched the films and brain activity monitored. From the videotapes, Duchenne smiles were distinguished from all other smiles and then correlated with activity in their brains. They found that the true enjoyment smile was associated with significant activation of the left frontal portion of the brain, the same part of the brain activated during positive emotions [3].   This landmark research made the connection between the true smile, the brain, and happiness.

But even this research is plagued by the chicken or egg problem. Which came first, smiling or feeling happy? Could the act of smiling itself, in the absence of a reason to smile, make a person feel good? Ekman and Davidson teamed up again to try to find out which comes first. For this experiment, they found students who were able to produce a true enjoyment smile on command and hold that smile for at least 20 seconds. This group was quite unusual in that less than 20 percent of the population can voluntarily contract the lateral portion of the orbicularis oculi, otherwise known as the eye crinkling muscle. The brain activity of these students was measured while they made enjoyment smiles versus social smiles (zygomatic (cheek raising) movement only). Ekman and Davidson found that the act of voluntarily making a Duchenne smile, even with no emotional trigger, activated the left frontal portion of the brain – the very same part of the brain activated during emotions of happiness, contentment, and joy. They suggest that just the act of smiling changes the brain and activates the areas of positive emotion and can create happiness on its own [4].


  1. Davidson, R.J., Hemispheric asymmetry and emotion, in Approaches to emotion, K.R. Scherer and P. Ekman, Editors. 1984, Erlbaum: Hillsdale, NJ. p. 39-57.
  2. Davidson, R.J., et al., Frontal versus pariental EEG asymmetry during positive and negative affect. Psychophysiology, 1979. 16: p. 202-203.
  3. Ekman, P., R.J. Davidson, and W.V. Friesen, The Duchenne smile: Emotional expression and brain physiology: II. Journal of Personality and Social Psychology, 1990. 58(2): p. 342-353.
  4. Ekman, P. and R.J. Davidson, Voluntary smiling changes regional brain activity. Psychological Science, 1993. 4(5): p. 342-345.


What Makes Babies Smile: The Science Behind Your Smile Part 3

We love to make babies smile!

The smile of a baby is one of the most coveted smiles. We will make ridiculous faces and noises, dance, sing, or stand on our heads to get a baby to smile. And when the baby smiles, we are absolutely sure that it is an true reflection of how likeable we are and how smart that baby is. But what does a baby’s smile really mean? And when do human smiles begin?

Infants begin to smile within the very first few weeks of life. The earliest smiles occur during active sleep (a type of sleep unique to babies when much of the brain is activated) and, during the first month, babies will most often smile when sleepy in response to a high-pitched sound (strange, but true) [1]. Babies who are blind have this same pattern of development, providing good evidence that the smile is hard-wired. After the first month, however, an infant begins to smile in response to what they see, and what babies like to see most are faces! Researchers believe that these earliest smiles represent the pleasure of the baby recognizing an object (such as Mommy or Daddy) [2]. By two months, infants begin to develop the smile that communicates their emotional experience of pleasure and contentment. From age two to six months, infants smile more and more often, frequently in response to interaction with a parent or caregiver.

Do babies have the same smiles as adults?

Babies have the same range of types of smiles as adults. They make the Duchenne smile and also the social smile. Do these smiles differ in meaning in the same way as they do in adults? For babies, does the authentic smile indicate happiness while the social smile is doesn’t? It seems that we learn very early to use the social smile. In ten-month-old babies, the Duchenne smile is displayed in response to the smile of their mothers, while babies give a social smile to a stranger. When babies make an authentic smile, the left frontal part of their brains was activated, the same part of the brain that is activated when adults experience happiness [3]. The Duchenne smile appears to be a clear expression of joy and engagement in play with other babies and adults [2].

Babies very quickly develop their own typical facial expressions. By six months old, some babies smile more and some less. These differences seem to be related to the baby’s temperament and affective style [4]. The patterns of individual facial movement, however, are similar in families and appear to be inherited. In a study of congenitally blind adults, researchers compared their facial expressions to those of their family members [5]. They found that the facial expressions of the blind family member were very similar to those of a parent or sibling both in appearance and frequency. It is clear that babies come into this world wired to smile!


  1. Messinger, D.S., Smiling, in The Encyclopedia of Human Development, N.J. Salkind, Editor. 2005, Sage Publications: Thousand Oaks, CA.
  2. Messinger, D.S. and A. Fogel, The interactive development of social smiling, in Advances in Child Development and Behavior, R. Kail, Editor. 2007, Elsevier: Oxford. p. 328-366.
  3. Fox, N.A. and R.J. Davidson, Patterns of brain electrical activity during the expression of discrete emotions in ten-month-old infants. Developmental Psychology, 1988. 24(230-236).
  4. Moore, G.A., J.F. Cohn, and S.B. Campbell, Mothers’ affective behavior with infant siblings: stability and change. Dev Psychol, 1997. 33(5): p. 856-60.
  5. Peleg, G., et al., Hereditary family signature of facial expression. Proceedings of the National Academy of Sciences of the United States of America, 2006. 103(43): p. 15921-15926.


The Science Behind Your Smile, Part 2: A Smile is Universal

So when you break it down to its basic elements, what is a smile? In technical terms, a smile is caused by the firing of cranial nerve VII which then activates the zygomaticus major (cheek raising) and orbicularis oculi (eye crinkling) muscles. There are different types of smiles, each representing different points on the emotional and psychological spectrum. We all recognize the authentic smile that you see on a child at play or on a person delighted by a birthday surprise. We also know the “buh-bye” smile of the flight attendant (made famous by a series of skits on Saturday Night Live in the 1990s) or the smile of the adult who must tolerate a neighbor’s annoying toddler.

Everyone recognizes a smile

It took the work of Paul Ekman, perhaps the world’s expert on facial expressions, to prove that the smile is universal across all cultures [1]. In the nineteenth century, Charles Darwin was inspired by Duchenne and became the first scientist to tackle the meaning of facial expressions, dedicating a book to the subject [2]. His thesis was that expressions have a biological basis and are the same for all humans. But by the 1950s, Darwin’s ideas had fallen out of favor as the major anthropologists, such as Margaret Mead, held the belief that facial expressions were not universal, but instead were culturally conditioned. These scholars believed that people learned through cultural experience that a smile meant happy and that a grimace meant sad and none of this was hard wired. In 1965, Paul Ekman, a young psychologist studying nonverbal behavior, decided to pursue research testing the hypothesis that facial expressions were culturally conditioned. What he needed was a group of people who had virtually no contact with any other culture in the world. Ekman spoke to physician Carleton Gajdusek who was studying an unusual disease, Kuru, which was endemic in Papua New Guinea. As part of his work, Gajdusek had filmed two native tribes for over six weeks. (This same physician later won a Nobel Prize in medicine for his work on viruses such as Kuru). Ekman studied these films, observed the facial expressions of the people, and he began to think that perhaps facial expressions were more universal that he had been taught. What he needed, however, was to go and interact with these tribes to study their expressions.

In 1967, Ekman went to Papua New Guinea to live with the Fore tribe. He found a few boys who had been taught English by missionaries to serve as his translators. His first experiment was to show the tribesmen a series of photographs of people making specific facial expressions (i.e. smiling, surprise, fear, anger, etc.) and ask them to tell a story based on the facial expression. What he quickly found was that the Fore tribesmen easily recognized what the facial expressions meant, even on strange Western faces. He then turned it around and had the tribesmen read a story and choose the photo of a facial expression that expressed the story. Again they all chose the correct expression. Finally, he told simple stories (such as “His friends have come and he is happy”) to members of the tribe and asked them to make a facial expression that fit the story. Again they made the same facial expressions that our Western minds would recognize. Ekman realized that the previously accepted conclusion of sophisticated scholars — that facial expressions are culturally determined and not hard-wired — was completely wrong. And he had discovered his life work as an expert on facial expressions. Paul Ekman continues his work today at the University of California at San Francisco and has written dozens of articles and nine books dedicated to the study of emotions and facial expressions.


  1. Ekman, P., Emotions Revealed. 2003, New York: Owl Books.
  2. Darwin, C., The Expression of Emotions in Man and Animals. 1872/2002, Oxford: Oxford University Press.