Researchers from the University of Parma and the University of Pisa in Italy observed a colony of geladas at NaturZoo in Rheine, Germany. They collected over 5,900 bouts of yawning, noting the social context in which the yawns occurred and the behaviors associated with the yawns. Their results were published in the February 6 issue of Scientific Reports.
The gum-bearing yawn was most common with males, especially high-ranking ones. This kind of yawn exposed the gelada’s impressive canine teeth, which stood out against the reddish-pink color of their gums and the inside of their mouths. It was often accompanied by a loud call, and the researchers believe the yawn functions as a long-distance display. Males used this yawn during periods of tension, such as the time right before feeding, suggesting it may serve to intimidate other geladas.
The other two less intense types of yawns were seen most in females during friendly interactions. The researchers found these yawns to be more contagious, and observed females mirroring the intensity of other females’ yawns. They believe these yawns are part of a complex communication system between geladas that often engage in friendly interactions.
via Wired
