Contagious yawning, is it as social as we thought?

Everyone knows it or has experienced it themselves. You see someone yawning and you get the urge to yawn yourself. It is often mentioned that when you yawn when someone else yawns you have a good relationship with that person. It was often said that contagious yawning has to do with empathy, empathizing with someone else’s feelings. Only is this really the case?

Researchers used to find contagious yawning only in social animal species. They also found contagious yawning more often in animals that were friends. In addition, researchers thought that special brain cells called mirror neurons caused you to yawn when others yawn. These brain cells were known to play an important role in empathy and synchronizing behavior between people. For Jorg Massen, behavioral biologist and researcher, the connection between yawning and empathy was the reason to learn more about contagious yawning. “This started with an interest in the phenomenon and eventually turned into a serious hobby.” His own research has now shown that contagious yawning also occurs in a less social animal species. Also, the relationship between contagious yawning and mirror neurons and thus empathy is becoming less and less certain. What about this and why do we yawn when other people yawn?

Contagious yawning, even for solitary animals.

Contagious yawning is a very puzzling phenomenon. Many studies have been done on this phenomenon in different animal species. Until now, this had only been found in social animal species, such as chimpanzees, bonobos, dogs and rats. All these animal species live in social groups. With his research, Jorg Massen has found that orangutans also yawn contagious, despite the fact that this ape species is not very social at all. So contagious yawning does not only occur in social animals. This can tell more about contagious yawning and whether or not it has a social function.

Unfortunately, another explanation is also possible for the presence of this behavior in orangutans. It is possible that the evolutionary ancestor of all great apes lived in social groups and also yawned contagiously. Since contagious yawning has been found in all great apes, it may have been inherited from this ancestor to all great apes. Orangutans may have retained this behavior, despite it having no function for this mostly alone living species. If behavior or an external characteristic does not entail any costs, this will continue to exist. Think, for example, of our tail bone. Humans do not have a tail, but the presence of the bone does not reduce the chance of survival. So the bone has no costs. Contagious yawning probably has no cost and so it is possible that this behavior has been preserved in the orangutans without serving any function for this ape species. Research into more solitary animal species may in the future provide more certainty about the function of infectious yawning.

Figure 2. Evolutionary tree of the great apes.
Contagious yawning could already be present in the ancestor (see arrow).

What does contagious yawning say about friendship?

“What has been found a lot is that yawning friends increases the contagiousness of yawning. When you see your friends yawning, you are more likely to yawn too,” explains Jorg Massen. Because friends were more likely to yawn, contagious yawning was thought to have a social function. Jorg Massen thinks this can be explained differently. Contagious yawning only works if you also look closely at the person who is yawning. It is quite normal for your attention to be more focused on your friends. This also increases the chance that you yawn with friends. The fact that you yawn with friends can therefore say more about your attention to your friends than it does about the function of yawning.

Empathy and mirror neurons

One of the reasons contagious yawning was seen as social and empathetic was because of the role of mirror neurons. These are special brain cells that take care of participating in the behavior of another. Mirror neurons become active both when you perform a behavior yourself and when you see someone else performing this behavior. This also ensures that when you see someone laughing, you laugh too. So they are just like real mirrors. It therefore seems quite logical that mirror neurons are involved in infectious yawning. After all, if you see someone yawning, you will yawn yourself. Studies just don’t find unequivocal evidence for this.

This can be explained by the fact that people have to lie still in an fMRI scan for this type of examination. This scan indicates which parts of your brain are active. People are then shown a gaping person and then have to lie still. Because people are not allowed to yawn and are probably also busy staying still, it is doubtful whether this scan measures the correct brain activity. These kinds of studies into the mechanism behind yawning, which brain cells cause it and whether or not it is empathy, are therefore difficult to interpret.

Then why do we yawn contagiously?

Then why do we yawn when other people yawn? Jorg Massen thinks the answer lies in “spontaneous yawning”. This is the usual yawning, which you do when you are tired, for example. Knowing the function of ordinary yawning may provide insight into contagious yawning. “The leading explanation for why we yawn is that it cools our brains. Cooling in the sense of bringing it back to the optimum temperature,” explains Jorg Massen. Bringing the brain back to the best temperature would be very functional in situations where you need to be alert. Jorg Massen thinks this could also be used to explain contagious yawning. For chimpanzees, for example, it is very functional if there is a threatening situation, such as a lion in the vicinity. Yawning can alert not only yourself, but also your fellow group members.

Why do we yawn when other people yawn, we are still not entirely sure. We do know that yawning when other people yawn probably says little about the relationship between the people.

Contact Samanta Rademaker if you have any questions left.

Sources:

van Berlo, E., Díaz-Loyo, AP, Juárez-Mora, OE, Kret, ME, & Massen, JJ (2020). Experimental evidence for yawn contagion in orangutans (Pongo pygmaeus). Scientific Reports , 10 (1), 1-11.

Massen, JJM & Gallup, A.C. (2017). Why contagious yawning does not (yet) equate to empathy. Neuroscience & Biobehavioral Reviews, 80, 573-585.