In the study, the researchers, Elisa Demuru and Elisabetta Palagi, observed 12 captive bonobos for 3 months at the Apenheul Primate Park in the Netherlands. Observation sessions lasted 6 hours and took place in both the morning and in the evening. A total of 1,125 yawns were recorded from the adult apes during the observation period.
Besides studying the contagious element of yawning, the researchers also looked into a potential empathetic component to the behavior. Empathy involves the sharing of emotional states and many recent studies suggest yawning could be a form of empathy.
In support of the empathy hypothesis, the researchers noted bonded male-female pairs were seen ‘infecting’ each other with yawns at a higher rate. However, the two scientists were unable to make any strong correlation between empathy and yawning based on their observations and analysis.