Do you yawn everytime a monkey yawns?...

"People yawn because they're tired, bored or nervous, but sometimes they yawn just because they've seen someone else do it. This behavior, contagious yawning, has now been documented for the first time in another species, chimpanzees.

Dr. James Anderson of the University of Stirling in Scotland and colleagues in Japan demonstrated that a third of adult chimps exposed to videos of yawning chimps will yawn themselves.


While no one knows precisely why people yawn contagiously, recent research suggests that the roughly 50 percent of adults who show the trait are more empathetic and score higher on self-recognition tests. Dr. Anderson said there is evidence that chimps demonstrate empathy, too. "And I knew that chimps showed self-recognition in a mirror or a photograph," he added. "So if they showed self-recognition, they were likely to show contagious yawning."

In the study, six female chimps at the Kyoto University Primate Research Institute watched the videotapes while in an experimental cubicle. All the chimps yawned somewhat, which was not unexpected, Dr. Anderson said. "Usually when they go into this experimental setup they are asked to do a cognitive task," he said. "Here they were asked to do nothing, so they may have been bored. But in two of the adult chimps, there was just an overwhelming increase in the frequency of yawning."

Three chimps brought their offspring along; none of the young ones yawned. Toddlers and young children do not find yawning catching either.

Next the researchers will study whether yawning can be contagious between species. After the chimp paper was published last month in Biology Letters, Dr. Anderson said, he received e-mail messages from dog owners claiming that they and their pets traded yawns. Dr. Anderson's next project will involve chimps watching tapes of human, canine and chimp yawns.

After spending hours watching chimps both live and on tape, Dr. Anderson doesn't need much convincing that cross-species contagious yawning occurs. "When I was analyzing the videotapes," he said, "it was enough to set me off."