Animals laugh says scientist

Dogs, chimps, and rats laugh when they're having fun, according to psychologist Jack Panksepp of Bowling Green State University. Reporting in the journal Science, Panksepp suggests that laughter may be an ancient emotional response older than humans. From BBC News:

Young chimps "play pant" as they mischievously chase and tickle each other.

And when rats play, they make chirps which some scientists associate with positive emotional feelings.

When rats are tickled in a playful way, they become socially bonded to humans and are rapidly conditioned to seek tickles, the US neuroscientist explains in Science.

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