Computer animations of yawning chimpanzees provoke the same irresistible grins in real chimps, according to an unusual study released Wednesday.
"Contagious yawning" is well known among humans, and earlier studies have shown that chimps are not immune to its suggestive influence either.
But the new research is the first to show that images seen on a monitor can provoke teeth-baring yawns in non-human primates too.
Matthew Campbell and colleagues of the Yerkes National Primate Research Center in Lawrenceville, Georgia divided 24 chimps ranging in age from nine to 43 years old into pairs.
Each pair was exposed to animated chimps in two short 3-D videos on a 48-centimetre (19-inch) screen. Only one of the videos showed the animals yawning.
The chimps may doing something deeper than simple imitation, for they may have an emotional tie with the cartoon character, the researchers believe.
"Contagious yawning is controlled by the same mechanism that makes emotions contagious," the study notes. "Our results strongly suggest an empathetic response to the animations."
The technique could provide an important tool for exploring animal behaviour and cognition, the study adds.
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