Yawning contagious among chimps

TOKYO – Ai, a 27-year-old chimpanzee in western Japan, watches another chimp yawn, quickly rolls back her head and soon is showing the pink inside of her mouth in a gaping yawn of her own.

“It’s another good example of how chimpanzees are so like us,” Tetsuro Matsuzawa, professor at the Primate Research Institute at Kyoto University, told The Associated Press on Monday. He took part in the Japan-based study.

The study, results of which were published this month in the British online journal The Royal Society Biology Letters, says that among the six chimpanzees under observation, two clearly yawned repeatedly in response to videos of other chimps yawning.

But three infant chimps accompanying their mothers did not respond at all, the study found.

Meanwhile, none yawned in response to images of other chimps just opening their mouths.

The pattern fits that of humans, Matsuzawa said.

When people watch yawning videos, roughly half yawn in response, while children under age 5 do not appear to find yawning contagious, he said.

Contagious yawning is thought to be a result of empathy and self-awareness, both of which require a sophisticated intellect, the study concluded.

Previously, it was believed that only older humans yawned contagiously because young children and animals did not have the necessary intellectual development to do so.

But the Japanese study said its findings provide further evidence that apes may possess an advanced level of self-awareness and empathy like mature humans.