Don’t try this at home, but tickling a gorilla, orangutan, bonobo or chimp can inspire bursts of grunting sounds.
Yes, that’s laughter, says Marina Davila Ross of the University of Portsmouth in England. She and her colleagues analyzed sounds of ticklish great apes as well as human babies and traced a shared family tree of laugh sounds. Laughter’s roots go back at least 10 to 16 million years, Davila Ross and her colleagues suggest online June 4 in Current Biology.
Here’s a link to the study.