Yawning is a behavior present in all vertebrates. It is characteristic for yawning, in addition to being in common with all vertebrates, that yawning can occur for different reasons, but always in the same form (we always yawn in the same way) and that it is “contagious” (a person gets a yawning urge if he/she sees another person yawning, hears yawning, reads or just thinks of it). Yawning in humans starts in mother’s belly, during (approximately) the 15th week of pregnancy.
Yawning is an unconscious action and we have very little or no control over it, so sometimes the desire to yawn occurs at the most inappropriate moments (the famous yawn of Sasha Obama in 2013, during the presidential inauguration of her father).
As one of the earliest and primitive behaviours in humans, it is still not fully explained, but there are theories of why it occurs. Although scientists have not been able to classify yawning completely, there is a basic classification in “rest yawn” – the one that occurs after rest and waking up and “emotional yawn”, which could still be referred to as “social yawning” because it is induced by social signals from the environment. Charles Darwin noticed that baboons, for example, are trying to intimidate the enemy by opening their mouth, which looks a little like yawning (one of the possible reasons for this is because all the teeth are visible by opening the mouth wide).
The “rest yawn”, which is not contagious (not induced by an external signal) and which spontaneously occurs at a certain point, occurs most when we are hungry, tired, or when we are bored – these are all the conditions in which our attention is becoming weaker and it’s hard to stay focused. It is believed that this kind of yawn is emerging as a signal to awake from that state of mind in which we are at the moment, or as a way to change from one state to another, such as from sleep to awake, from awake to sleep, from anxious to calm, from boredom to a state of increased concentration.
The “emotional yawn” could easily be described as contagious yawning that occurs when we see or hear someone yawn. One of the theories why this “contagion” occurs is to show empathy (compassion) towards others. This conclusion has come about because it has been shown that people will rather yawn if they see a close person (a family member or friend) yawn, instead if they see a stranger doing it. Likewise, contagion occurs more within the same species – there is a less chance that a person will yawn if he/she sees an animal yawning. Yet, the second theory seems more likely. It says that yawning is a form of communication. When we yawn, we send a visible signal that we are bored, tired, or hungry, which are all situations in which we’d use someone’s help.
There is also an interesting phenomenon that occures while yawning- people with one side of the body paralized, at the very moment of yawn recover function of the paralyzed side, which lasts only as much as the yawn, on average about 6 seconds.
How many times have you yawned while reading the article? 🙂