London, Aug 13 (IANS): Just as humans sometimes find it impossible to resist yawning as a response to another person's yawn, bonobos, our closest evolutionary cousins, too feel the same urge, says a study.
The findings indicate that the apes too can feel empathy for their fellow beings as in humans and apes yawn contagion echoes emotional contagion, the transmission of a feeling from one individual to another, the most basic form of empathy.
When the yawner and the responder were not friends or kin, bonobos responded to others' yawns just as frequently and promptly as humans did.
"Thus, emotional contagion is not always highest in humans," said lead researcher Elisabetta Palagi from the University of Pisa in Italy.
However, humans did respond more frequently and more promptly than bonobos when friends and kin were involved.
This may be because strong relationships between humans are built upon complex and sophisticated emotional foundations linked to cognition, memory, and memories, the researchers said.
For the study, over the course of five years, the researchers observed both humans and bonobos during their everyday activities and gathered data on yawn contagion by applying the same ethological approach and operational definitions.
Two features of yawn contagion were compared: how many times the individuals responded to others' yawns and how quickly.
The study suggests that differences in levels of emotional contagion between humans and bonobos are attributable to the quality of relationships shared by individuals.
The study appeared in the journal PeerJ.