I was sitting in my room and all of a sudden I got really happy, I was dancing around and jamming out to whatever music I had playing and I started thinking about why I was happy. In general it’s pretty easy to read someone’s emotion based off of their facial expressions, whether it’s a smile when they are happy or the eyebrow raise when they are ticked. As humans we are usually really good at reading into these expressions and knowing exactly what is going on, but that got me to wondering why exactly we smile when we are happy? Why do we make the facial expressions we do in response to our emotions?

As I started my research, I came a cross Paul Ekman and his studies. Ekman is a scientist who has written several books about his findings. In his book “Unmasking the Face: A Guide to Recognizing Emotions from Facial Clues,” Ekman shows well researched data on several aspects of emotion. In a study he conducted he showed people pictures of emotions and then had them either pick the word that corresponds to the image or come up with their own word for the picture. His study found that across the board the emotions happy, sad, surprise, fear, anger and disgust were constant amongst the population. In another study Ekman conducted he showed stress inducing videos to American and Japanese college students once by themselves and then again with someone in the room asking questions. This study was constructed to see if the emotions were constant across culture. To avoid the confounding variable of “learned recognition” and response to popular media, Ekman conducted this study in New Guinea, where individuals had no connection with the outside world. The tests had to be modified slightly due to the language barrier and varying social norms, but this test also held with Ekman’s hypothesis that Emotions are constant among all humans. Due to Ekman’s thorough investigation, attention to potential third variables, and large sample size he was able to show that facial expressions are constant across humanity.

Facial expressions as we know can be both voluntary and involuntary. Humans can vary their expressions to a point, but through the findings of Ekman they still follow the idea that facial expressions are constant. But I still hadn’t found why. I came across an article that was not a science journal and was not as credible as Ekman and his book but in it I started to get answers. Lauri Nummenmaa, a psychologist at Aalto University stated “Our emotional system in the brain sends signals to the body so we can deal with our situation.” This is known through psychology with the autonomic and somatic nervous systems. Just as it is animal reaction to run when something scares it and our body naturally calms itself down once it is safe, it is a rush of signals that causes emotions.

The emotions are caused by these signals in conjunction with chemicals in the brain. When someone is depressed there is some sort of imbalance of the chemicals in the brain, which is why certain drugs are used to correct the imbalance. The brain is very complex and different studies differ on exactly which chemicals are part of happiness, some having more components than others. The neurochemicals that are agreed upon across the sources I referenced are Dopamine, Oxytocin, Serotonin and Endorphins. Each is responsible for a different aspect of happiness. Dopamine is considered the “reward molecule,” this chemical is released anytime someone has that feeling of accomplishment. Oxytocin is known as the “bonding molecule,” this is the chemical is released when someone is with a loved one and is experiencing physical contact. Serotonin is the “confidence molecule,” which is associated with self worth. Endorphins are linked with physical activity of both innocent and sexual natures and make them a pleasurable part of human life. These chemicals, potentially combined with many others, are the components of happiness. 

So to date it has been established that humans are constant in their expressions and they have the same chemicals coursing through their bodies, which are the associated cause of emotion, so it seems that chemicals cause facial expressions. This is a correlational conclusion, but it is widely accepted. Dr. Nakia Gordon on the other hand states that smiling can actually cause ones mood to increase, opening up the possibility of reverse causation.  Charles Darwin  had suggested that facial expressions were an indication for animals to communicate, an animal would bear its teeth as warning, and that humans re-established the idea of bearing teeth as a form of greeting. Darwin’s ideology may be correct but it also may not, it is unclear whether human expressions are only based off the chemical responses, or if there is a third confounding variable that influences why we make certain expressions in conjunction with certain emotions. Either way, the study of why we smile is one that has puzzled many scientists!