Researchers carried out "tickling sessions" on gorillas, chimpanzees and orangutans and compared the sounds to recordings of humans laughing.
"How was work today, dear?"
"You know, the usual. Went to a meeting, analyzed some data, tickled a couple of apes."
And it's not just apes:
The researchers also found that other animals, including bats, made different sounds when they were tickled, but that these may not be the same as laughter.