Yawning is one of the most contagious aspects of the human body, and seems to spread with ease throughout a crowded room. It’s likely that you’ll yawn at least once before finishing this article. Where does this tendency come from? Yawning seems to be an individualistic survival instinct, but then why is it so often mirrored by a group? Luckily, research has been done to study this remarkable, curious trait. Even though this deals with the brain, something we know relatively little about, there are credible theories to explain this phenomenon.
One popular theory was that yawning was a response to the brain sensing too much carbon dioxide or too little oxygen, but in 1987 this theory was disproved due to a study showing no change in the frequency of yawning when being exposed to more oxygen or more carbon dioxide.
The most common theory now is that yawning is a cognitive empathic response. A study published by Springer, a science journal, used functional magnetic resonance imaging, which detects changes in blood oxygenation in response to neural activity. Subjects of the study were shown videotape of others yawning faces. In response to this, researchers saw responses in the form of neural activity in the right inferior frontal gyrus, the area of the brain responsible for inhibition and attention control. This reaction indicates a physiological and emotional response for yawning. In simpler terms, yawning seems to be a function of empathy. This theory is being supported more and more now. For example, kids with severe autism, which affects social perception, almost never caught a ‘social’ yawn. Infants as well, with less developed brains were much less likely to catch a ‘social yawn’.
The frequency of yawning may also be a subconscious way of communicating sickness. Excessive yawning has been in seen in patients with multiple sclerosis, Lou Gehrig’s disease, during radiation therapy. On the other side of the spectrum, yawning seems to occur less frequently with people who have Schizophrenia. Although this looks promising, this correlation is most likely a secondary symptom probably due to a chemical imbalance.
Another promising path is that yawning has a connection to early development which then later transitions into internal safety. It’s shown that as early as eleven weeks old fetuses begin to yawn, showing that in at least some scenarios this is an involuntary action. This also leads to another theory. Yawning distributes a chemical called surfactant. Surfactant coats tiny pockets in the lungs to help keep them open, making it essential to the safety of newborns. This instinct could then transition into yawning for the purpose of stretching. Yawning stretches the lungs, preventing airways from collapsing. So when breathing is shallow and sparse, like when we go to bed, breathing may be a safety mechanic.
