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Contagious yawning isn’t a myth. It’s a real, scientifically demonstrable phenomenon. We yawn when we see someone else yawn. The sound of yawning makes us yawn. The yawning contagion can even spread between species. Studies show that chimpanzees start yawning when they watch videos of other primates yawning. Dogs exhibit contagious yawning, even in response to human yawns. You might be yawning right now, as you read this, and it’s probably not because you’re sleepy and certainly not because you’re bored (heaven forbid). So, why then? Why is yawning contagious?
In 2013, scientists in Zurich, Switzerland, had 11 healthy volunteers watch a set of videos while plugged into an fMRI, which tracks brain activity in real time. The videos displayed human faces yawning, laughing, or with neutral expressions. As the researchers expected, subjects yawned in response to the yawning videos more than half the time, which is the typical percentage. Also as they expected, the participants did not similarly react to the laughing or neutral faces. The fMRI results, however, were profound: As the subjects experienced contagious yawning, the fMRI signal lit up the inferior frontal gyrus, an area we know to be part of the mirror neuron network, which functions to help create mental representations of action. In contrast, the mirror system was quiet while the subjects saw the neutral or laughing faces.
Scientists theorize that when we watch someone yawn, mirror neurons simulate the action in our minds. Those simulations can change our behavior. Try to use mental imagery to simulate a yawn in your mind. Really focus on it. You can probably make yourself yawn that way. Similarly, by simulating an observed yawn, mirror neurons cause us to yawn, imitating what we see.
It might seem silly that yawning has become the target of serious scientific inquiry. At least scientists can have a sense of humor about it, as in this title of an article from the journal Frontiers of Neurology and Neuroscience: "Yawn, Yawn, Yawn, Yawn; Yawn, Yawn, Yawn! The Social, Evolutionary, and Neuroscientific Facets of Contagious Yawning." Nevertheless, the research is not devoid of insight. It has actually revealed a number of potential connections between this seemingly meaningless behavior and basic components of human nature.
A chain reaction of yawning doesn’t happen in every instance of observing a yawn; it happens in some circumstances more than others. Consider the following study: Neuroscientists in Italy spent four months studying a group of 21 baboons living in a large alcove in the zoo. Over those four months, the researchers observed the baboons from 6:00 a.m. to 10:00 p.m. daily and recorded each yawn that they witnessed, the precise monkey that yawned, and the time at which the yawn occurred. They also noted many of the other behaviors the animals exhibited, including sleeping, walking, feeding, and grooming. The neuroscientists’ question was how the interaction between the baboons affected their yawning patterns.
It turned out that the incidence of contagious yawning correlated best with the time the baboons spent grooming one another. This trend persisted even after the experimenters controlled for the effect of proximity among the animals. So, it wasn’t simply being around one another that led to yawn spreading but the act of mutual grooming. That’s significant because primate grooming is more than just practical; it’s a demonstration of affectionate social relationships. Baboons groom each other when they feel close. The more they groom, the closer they feel. The closer they feel, the more infectious their yawns become. If the results of this study are true, emotional closeness correlates with the degree of yawn contagiousness.
What does this mean?
Mirror neurons are likely involved in the spread of yawning. If that’s true, and social closeness makes yawning more contagious, then it would follow that social closeness is associated with mirror neuron activity. Many neuroscientists today believe that the ability to simulate what someone else is doing, using mirror neurons, helps you experience what that person is experiencing. It helps you "put yourself in his or her shoes," as we tend to say when we understand someone around us. In short, the association between primate social relationships and yawning contributes to a body of research that claims that mirror neurons create the basis for empathy.
This article is an excerpt from my book, NeuroLogic: The Brain's Hidden Rationale Behind Our Irrational Behavior. Available now!
