The photo shows a Macaque monkey yawning. Look once again. He is tired and so sleepy that his eyelids are drooping; he is gently putting his hand on his mouth and sighing deeply, exhaling loudly with pleasure. What are you doing now? Can it be that you have yawned?
Believe it or not, scientists do not know why yawning is contagious. They managed to discover the Higgs boson, they understood what happens when you travel at the speed of light, and they even managed to dissect a specific gene from DNA and calculated how a cosmic probe lands on a comet. However, they do not have an answer to a completely simple question: how is it possible that a completely rested and wide-awake person suddenly feels lethargic, relaxes, inhales deeply and opens their mouth widely at the sight of another person yawning?
Yawning is a reflex. People yawn when they feel tired, sleepy or bored or when they see or hear other people yawning. Even thinking about yawning often causes yawning. While writing this text, for example, the author yawned at least 15 times.
It seems that yawning contagion is a perfect question for researchers – not only is it interesting and amusing, but by researching it, the scientists do not have to launch anyone to space, they do not have to dissect animals or people, and they do not require an underground, medium-town-sized tunnel.
During a yawn a muscle tensor tympani contracts in the middle ear. During this, it appears to us that the yawning noise is being created inside our heads, but it has nothing to do with air vibrations but with the mechanical movements of the hearing mechanism itself.
Despite these engaging findings, turns out that the cause of contagious yawning is difficult to determine. There are multiple theories in the field of physiology and psychology – around 20 – attempting to explain this phenomenon, although none has been proven yet. For example, the so-called chameleon effect or ‘nonconscious mimicry’ – unintentional mirroring has been cited. Other researchers describe yawning as a reflex triggered by a stimulus – the other person’s yawning.
One of the more dominant explanations is that the cause of contagious yawning (though only in primates) is empathy. According to this theory, we participate in the emotions of others, people close to us, needing to feel what they feel, out of compassion, so we often mirror a close person through movements or activities.
The theory on empathy as a cause of contagious yawning may have been confirmed by research carried out among children with autism. Since autism spectrum disorder (ASD) affects the social and communicative development of children, even the capacity for empathy, researchers thought that the research among children with autism could yield some answers. Indeed, it turned out that these children are not prone to contagious yawning, which is why empathy theory may be somewhat more grounded than others.
What perhaps proves this theory on empathy as the cause of contagious yawning even more, is the fact that people yawn more often if they see a person close to them yawning compared to a stranger’s yawning. Even dogs yawn more often if they see (or just hear) their owner, compared to an unknown person.
Yawning is not contagious only in dogs, but in other animals too – birds, reptiles, cats, chimpanzees and not necessarily within a species – but the causes are apparently diverse. Baboons yawn in the presence of enemies – perhaps to show their huge canines. Siamese fighting fish, popular in aquaristics, yawns only in the presence of other fighting fish, particularly before the attack. Yawning is part of a greeting ritual for Adélie penguins.
The yawning of people is contagious to dogs, and this question has especially intrigued scientists. They first assumed it was for evolutionary reasons, and it was connected to the domestication of a dog living beside a man since forever. However, this theory was refuted when it turned out that wolves were equally susceptible to contagious yawning – the stronger the bond between individual wolves, the more often contagious yawning appeared in wolves.
M.Đ.