NEW YORK — When scientists set out to trace the roots of human laughter, some chimps and gorillas were just tickled to help. Literally.
That’s how researchers made a variety of apes and some human babies laugh. After tickling three human babies and 21 orangutans, gorillas, chimps and bonobos, and analyzing the sounds, they concluded that people and great apes inherited laughter from a shared ancestor that lived more than 10 million years ago.
After measuring 11 traits in the sound from each species, researchers at the University of Portsmouth in England mapped out how these sounds appeared to be related to each other. The result looked like a family tree. Significantly, that tree matched the way the species themselves are related, the scientists reported online Thursday in the journal Current Biology. They also concluded that while human laughter sounds much different from the ape versions, its distinctive features could well have arisen from shared ancestral traits.
