Contagious Yawning, Also Seen in Orangutans

Yawning is a highly contagious behavior, but its mechanisms and the cause of why it is contagious remain poorly understood. Scientists have suggested that contagious yawning might be more common in social animals. However, findings are inconsistent and its function remains debatable.

Researchers from Utrecht University, Leiden University, and the Benemérita Universidad Autónoma de Puebla in Mexico have studied contagious yawning in orangutans because data about them is missing. Previous studies have demonstrated that contagious yawning is present in chimpanzees and bonobos. They also hope to see the same result on orangutans which are considered solitary animals.

The researchers published their study in the journal Scientific American.

Contagious Yawning Found in Solitary Animals

An international team of researchers investigated contagious yawning in orangutans in a zoo for primates in Apenheul in Apeldoorn. The research was led by Utrecht University's behavioral researcher Jorg Massen, in which they observed how orangutans react when they watch videos of other orangutans with a neutral and yawning face.

The researchers found that although orangutans are solitary animals, they are also like humans when they see the same species yawning. They too mimic that behavior and yawn, according to a press release by Utrecht University.

"Contagious yawning is a phenomenon that has fascinated science for a long time, but interestingly enough, we still do not really know what its function is. By looking at our close relatives and at animal species that vary in their sociality, we try to get a better picture of this", Jorg Massen said.

Contagious Yawning in Orangutans Might Be Due to Familiarity

Aside from investigating whether orangutans also display the automatic behavior of contagious yawning usually found in social animals, the researchers also studied whether the reaction of orangutans yawning contagious is influenced by how familiar the orangutans in the video to those watching it.

The researchers showed the orangutans videos of group members yawning, as well as strangers doing the same thing, and a 3D orangutan avatar named Waldo, which was donated by graphics designer Paul Kolbrink of the XYZ Animation.

They found that the orangutans are more likely to exhibit the automatic response of yawning on real orangutans, regardless if they are a member of the group or they are strangers. However, the yawns of Waldo did not result in more yawns from the orangutans viewing him.

The results of the study once again contradict the popular belief that contagious yawning only happens on social animals. The researchers also noted that perhaps contagious yawning is something that exists in all species of great apes.

They recommend further investigation of yawning in more solitary animals, such as cats, foxes, pandas, snakes, tortoises, and other reptiles. Evy van Berlo, from Leiden University and the study's first author, said that only by studying contagious yawning on a wide variety of animals could answer the questions of why it exists and what is its specific function.

Besides, even humans yawn too when they see orangutans yawn. Co-authors Alejandra Díaz-Loyo and Oscar Juárez-Mora from the Mexican Benemérita Universidad Autónoma de Puebla said that this contagious yawning between different species could also be an interesting next step in studying the mechanics behind yawning.