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Is Yawning in Bonobos as Contagious as It’s in Humans?

big yawn

Image credit: Female Bonobo Yawning / Elisa Demuru CC-BY-SA 4.0 via PeerJ

With comparison of the “yawn contagion” effect between mankind and bonobos, the closest evolutionary cousins of humans, scientists have found that both species are similarly quick to catch a yawn from mere acquaintances or strangers. However on the other hand, a friendly relationship between individuals would be more important to feeling empathy than the fact that those individuals may come from the same species.

It is difficult to quantify the ability to experience someone else’s emotions. In order to make measurement of the very elementary form of empathy, also recognized as emotional contagion, scientists are trying to identify the transmission of a feeling from one individual to another. You can easily see such transmission in the mirroring of facial expressions between an “emitting face” and a “receiving face.” According to the previous studies, in humans and bonobos, followed by an emphatic trend, yawn contagion does occur more frequently between mates and relatives as well as friends.

In the direct comparison of the empathic abilities between humans and bonobos (Pan paniscus), Elisabetta Palagi and his colleagues from the University of Pisa have been observing these two species in regard to their everyday activities for the past five years. In such observation, scientists collected data from 33 adult humans (1,375 total yawn events) in social events and during meals and 16 adult bonobos (2,123 total yawn events) in zoos in the Netherlands and Germany. By doing so, Elisabetta Palagi’s team is engaged in comparison of two features related to the yawn contagion: how frequently and how quickly the individuals responded to someone else’s yawns.

As for bonobos, if the yawner and the responder weren’t friends or kin, they would respond just as frequently and quickly as humans did, but humans responded more frequently and more quickly than bonobos if the yawner was friend or a relative.

In summarizing their finding, Palagi said, the basal level of empathetic capacity was the same in humans and bonobos, however when an emotional bonding was concerned, people overcame bonobos.

In the paper published in the recent edition of PeerJ, the scientists confirmed that the positive feedback related to emotional affinity and the mirroring process appeared to move faster in humans than in bonobos. As far as humans were concerned, these over-activation could give good explanation about various other kinds of unconscious and imitative responses, such as facial expressions of being happy, pained, and angry.

Journal reference: Palagi, Elisabetta, Ivan Norscia, and Elisa Demuru. “Yawn contagion in humans and bonobos: emotional affinity matters more than species.” PeerJ 2 (2014): e519.