Dr. Jana Ikeda, DDS - Boulder Dentist | The Science of Smiling
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The Science of Smiling

14 Aug The Science of Smiling

Smiling is a natural human response. Nobody teaches us how, but from the time we’re babies we smile when we’re feeling happy.

So what does science have to say about it?

10Why Do We Smile?

Many species of animals exhibit behaviors that look like smiling, but their intentions are very different from ours. Large felines, like tigers and lions, “fang-flash” to show aggression or establish dominance. Another common cause of an animal showing one’s teeth is nervousness or fear.  Behavioral research shows that primates also bare their teeth primarily as a sign of submission. Instead of an expression of fear or a scare-tactic, smiling is used to say “I recognize your dominance, please go easy on me”.

In some higher apes (such as chimpanzees) smiling also occurs between equals. When reuniting with an equal after a long time apart, apes will flash their teeth before embracing. This is the most affectionate kind of smile observed in the wild. Researchers believe this type of behavior is what evolved into the friendly, happy smiles in humans.

What Makes A Smile?


From a physiological standpoint, there are two kinds of smiles: genuine, and “fake”. The difference comes from the muscles used to create the smile. The zygomaticus major controls the corners of the mouth, and is used to create what is known as a “social smile”.

On the other hand, sincere smiles are formed by the contracting of the obicularis occuli, which encircles our eye socket. If you’ve ever heard the term “smiling with your eyes”, this is the reason! As it turn out, our brains are pretty good at telling the difference in others’ smiles. When we see another person smile, on an subconscious level, we mimic the expression we see. This allows us to experience the quality and type of smile we’re seeing, and then make a judgement about whether it is sincere or not.

The True Power of Smiling

There have been multiple studies on the effect of smiling on the mind and body, and the results all point to one main idea: smiling is great for your health!

Smiling is the body’s natural response to experiencing something positive or seeing someone we care about. A signal travels from the cortex of your brain to the brainstem (the most primal part of our brains). From there, the cranial muscle carries the signal further towards the smiling muscles in your face. But this is where things get interesting…

Smiling creates a positive feedback loop; something makes you happy, so your brains releases endorphins and sends a signal to your facial muscles causing you to smile. When your facial muscles contract, it then sends a signal back to your brain, further stimulating your brain’s reward system. This loop means that being happy makes you smile, and conversely, smiling also makes you happy. You can use this neurological loop to actually trick your brain into feeling happy, all you have to do is smile and you’ll start to feel better in no time!

Smiling can also help the people around you. We’re wired to mimic the facial expressions of those around us (on a subtle level), so when we see someone smile we start to smile too, thus starting the positive feedback loop. In this way, you can spread happiness all around you, just by smiling at someone on the street.