We have all heard these platitudes: "just put on a happy face" or "turn that frown upside down." Can the simple act of smiling actually make us feel better? Might we even become addicted to smiling? The answer may have everything to do with the evolution of the frontal facial bones and that popular feel-good neurotransmitter dopamine. Our face is formed by a variety of rather thin bones that are made somewhat fragile due to the presence of large air pockets called sinuses. The muscles that attach to these bones contract when we are happy or when we want to laugh. The resulting facial expression is universally recognized as a smile and indicates our positive emotional status. Sometimes, people present fake smiles; these can also be universally recognized as being counterfeit.
We can all tell the difference between a real smile and a fake one. When we see someone showing a fake smile we know they lack sincerity in what their faces is trying to convince us about their underlying true emotions. But how does the brain achieve both types of smiles using the same facial muscles? It all depends upon which part of the brain initiates the smile. If the brain's dopamine neurons initiate the smile, then the smile looks sincere. If the brain's motor cortex initiates the smile, i.e. if we are consciously willing ourselves to smile, then a slightly different set of facial muscles are activated. It can be difficult to describe precisely how real and fake smiles differ, but we are all very capable at knowing the difference. But can forcing yourself to smile produce the same kinds of good feelings as a real smile does?
Thus far you know that activating the release of the feel-good chemical dopamine brings pleasure. Indeed, anything that induces the release of dopamine in the brain is so pleasurable that we frequently become addicted to the experience. For example, cocaine and coffee both release dopamine in the brain. The release of dopamine in the front half of our brain is accompanied by a real smile—an expression that it initiated and orchestrated. It's convenient that the same chemical in our brain that allows us to feel pleasure also arranges a facial representation of our pleasure to those around us. But can this process be reversed? What about putting on that happy face? Can the simple act of smiling bring pleasure? Yes.
When we smile, fake or real, the contractions of the facial muscles slightly distorts the shape of the thin facial bones. This slight distortion in their shape leads to an increase in blood flow into the frontal lobes of the brain and increases in the release of dopamine (Iwase et al., 2002, Neuroimage 17:758). As a result, walking around all day with a smile on your face will bias your mood to be happier. Not only will you be happier but your smile might spontaneously induce the release of dopamine in someone else's brain—now that truly demonstrates the power of a smile.
© Gary L. Wenk, Ph.D. Author of Your Brain on Food (Oxford, 2010)