Why are yawns contagious?

Why are yawns contagious as an involuntary phenomenon?

We are in a boring family gathering. Out of politeness we try to keep our composure and pretend to care a little about what our older relatives are talking about.

But the little ones in the house don't care about composure. They get bored and have no qualms about yawning as an overt act of such a tedious meeting. The invisible puff of air travels through the room. It approaches us, little by little. It takes shape from deep inside us and, without being able to help it, we answer the yawn by imitating it.

While the one who was speaking looks at us with an indignant face, we ask ourselves.... why do yawns become contagious? Let's find out below.

Why do we catch yawns?

Yawning is a human and not so human act that, although it has aroused the interest of the scientific community since science has been science, it is still quite mysterious why it originates, and even more so why it is contagious. However, a few things are clear about this peculiar involuntary act.

The first is that we manifest it very early on, even before we are fully formed, in the mother's womb.. We can already observe how the fetus yawns only 20 weeks after conception.

Moreover, humans are not the only ones who yawn. It has been observed that animals very close to us also yawn, as is the case of chimpanzees and dogs, respectively. Interestingly, it has also been observed in fish, birds, wolves and elephants, animals that, to a lesser or greater extent, have very clear social behavioral patterns.

Although general culture already indicated that we yawn more when we are about to go to sleep and when we have just woken up, scientific research has confirmed this assumption. Moreover, we also yawn when we feel hungry, we also yawn when we feel hungry and, of course, when we are bored out of our minds..

But what is surprising about yawning is its high degree of contagiousness, even though they do not exist physically speaking, they are just actions. It has happened to almost all of us when someone around us yawns and, without being able to help it, we start yawning with him. This is not strange at all, since it is reported that about 60% of the population is sensitive not only to the act of seeing others yawn, but also to hearing others yawn and even reading the word "yawn". At this point, how many yawns have you yawned already?

Theories of yawning

Let's take it one at a time. Before understanding how yawning is contagious, it is necessary to understand why yawning occurs in the first place..

At first sight, yawning does not seem to have either a good or a bad effect on us. If it were harmful, sooner or later we would have noticed some disadvantage associated with yawning and, without digging too deep, it does not seem to offer us any advantage.

However, bearing in mind that this involuntary act occurs in other species and has therefore survived over the course of time, has survived throughout evolutionary history, it must be of some use.history, it must be of some use.

It is for this reason that up to three theories have been put forward in the scientific community, with considerable support, to explain why yawning occurs.

1. The oxygenation theory

Even before our era, the Greek physician Hippocrates of Cos (460 B.C. - 370 B.C.) held the idea that we yawn as a mechanism to eliminate noxious air. as a mechanism to eliminate the noxious air that we accumulate inside us.. In a way, it seems that he was not too far wrong.

The oxygenation theory of yawning defends the idea that when our Blood oxygen levels decrease, drowsiness occurs. To counteract this, the brain causes yawning to introduce a lot of air into the body to quickly raise the levels of the gas of life.

However, although quite logical, this theory has its detractors, basically because of the existence of another mechanism that seems to be very effective in this purpose: breathing fast, as happens when we do sports.

If blood oxygen levels are reduced, it would be logical to think that, rather than yawning, the body would accelerate breathing, a process that involves a greater supply of oxygen to our bloodstream and that is relatively easy to control.

2. The theory of activation

As we have already seen, and almost a general cultural knowledge, is the fact that it is known that yawning is more frequent before and after sleep. it is known that yawning is more frequent before and after sleep.. That is, they occur when we feel very sleepy.

The idea behind the arousal theory is that we yawn to increase our level of alertness. That is, our brain sends us a message that we should be more alert.

However, although there is a fair amount of research suggesting that this theory may be true, it is still rather doubtful that the levels of alertness before and after yawning are significantly different. It's not as if we yawn and are as alert as if we had a cup of coffee....

3. The thermoregulation theory

Although the other two theories have some scientific support, the thermoregulation theory is the one that has gained the most strength.. This theory argues that yawning regulates the temperature of the brain, as a way of cooling.

This makes sense, since it has been observed that the body temperature is precisely the highest of the day and that, by yawning, we would be able to reduce it and make our brain work better.

Also It has also been observed that if the ambient temperature is warm, people yawn more, while low temperatures have the effect of making our brains work better.while low temperatures have the opposite effect. In fact, it has been seen that putting wet cloths in very cold water on the forehead makes yawning practically disappear.

Causes of this phenomenon

While yawning has been found to be present in many species, the contagion of this involuntary act is somewhat less common.. In addition to humans, other species such as dogs, wolves, chimpanzees, different types of fish and birds, and even elephants can catch yawning. On the basis that most species in which yawning is contagious also exhibit complex social structures, it has been suggested that yawning may have a relational function.

Communication and synchronization

One of the hypotheses about yawning is that it is a mechanism of communication and synchronization between individuals of the same species. That is, it would serve as a way to organize collective behavior, coordinating the behavioral patterns of group members.

This has its logic given that yawning is not the only yawning is not the only thing that is contagious.. In the human case and also in dogs, if you see someone eating, you feel like eating, and if you see someone moving, you are more inclined not to sit still. The yawning would serve to put the group in synchrony either maintaining the degree of activation or making sure that everyone thermoregulates correctly.

2. Empathy

Surprising as it may seem, it could be that the degree of empathy is behind the contagiousness of yawning. In this case, it would not only be a mechanism to make the rest of the group imitate it and thus synchronize, but a way of being able to tune in behaviorally and emotionally with others.

By means of neuroimaging techniques, it has been discovered that yawning activates the same neurological mechanisms involved in empathy, in addition to the activation of the well-known neurological mechanisms involved in empathy.In addition to activating the well-known mirror neurons, cells specialized in mentally replicating the movements we see in others, allowing motor learning.

Bibliographical references:

• Bartholomew AJ, Cirulli ET (2014) Individual Variation in Contagious Yawning Susceptibility Is Highly Stable and Largely Unexplained by Empathy or Other Known Factors. PLOS ONE 9(3): e91773. https://doi.org/10.1371/journal.pone.0091773
• Rossman, Z. et al (2020). Contagious Yawning in African Elephants (Loxodonta africana): Responses to Other Elephants and Familiar Humans. Front. Vet. Sci., 1-8.
• Gallup, A. C. y Gallup, G. (2008) Yawning and thermoregulation. Physiology & Behavior, 95(1–2, 3) 10-16.
• Gallup AC, Eldakar OT. (2013).The thermoregulatory theory of yawning: what we know from over 5 years of research. Front Neurosci. 2;6:188. doi: 10.3389/fnins.2012.00188.
• Guggisberg AG, Mathis J, Schnider A, Hess CW. (2010) Why do we yawn? Neurosci Biobehav Rev. 34(8):1267-76. doi: 10.1016/j.neubiorev.2010.03.008.
• Guggisberg AG, Mathis J, Hess CW. (2010). Interplay between yawning and vigilance: a review of the experimental evidence. Front Neurol Neurosci 28:47-54. doi: 10.1159/000307079.