Why, when someone yawns next to us, do we also have a strong urge to yawn? Several theories have tried to find the answer.
I yawn, you yawn and in five minutes we start again… This little involuntary game is well known: when someone nearby starts to yawn, we often feel the need to do so too. Sometimes you even need to think about it for a moment to start opening your mouth wide and letting out a deep sigh. No one really knows what triggers this automatic (and often involuntary) response, but experts have proposed a few theories.
It is important to first know what actually causes yawning, which happens on average up to 20 times a day. According to one hypothesis, it is above all a means of regulating brain temperature. Studies have shown that a warm glove applied to the forehead caused more yawning than a cold glove. Another hypothesis is that yawning, by stretching and distorting the face, gives us a very temporary boost and increases attention when our alertness drops.
All this can happen when you are alone of course, we then speak of spontaneous yawning. But what disconcerts us is the “contagious” group yawning. So why do we yawn in response to another person? It could actually be an evolutionary adaptation of humans, aimed at synchronizing group behavior. Imagine a group of prehistoric men, keeping vigil all night against predators and enemies. If one of them starts to get sleepy, it’s likely that the others will start to get sleepy as well. When the first person yawns, this signal will prompt everyone else to do the same, increasing the group’s alertness and safety.
Simultaneous yawning could therefore increase our collective consciousness or strengthen our social bonds. Some research also suggests a link between yawning and empathy, the ability to share another person’s emotions. A 2020 study found that people were more likely to yawn with family or friends. The deeper the bonds, the more common the yawning, the study suggested.
Whatever the reason, this type of yawning seems linked to a form of social intelligence. Although many animals – from birds to fish to reptiles – have been caught yawning before, it appears that only highly intelligent and social species such as primates yawn in response to others. In 2022, researchers discovered that humans even yawn in response to the yawns of other animals.
However, some researchers question these theories on “social” yawning, such as psychologists Rohan Kapitány and Mark Nielsen. They suggested that confirmation bias could lead us to the wrong conclusions: in short, we more often notice the rare cases where yawns seem to be transmitted from one person to another and miss the much more numerous cases where yawns yawns are not imitated.