Robert Provine, a neuroscientist at the University of Maryland, Baltimore County who studies laughter, notes that dogs pant in a certain way when they're playing, and rats are known to chirp.
So he thinks the roots of laughter might go even further back and would like to see more studies like this one that compare different animals' playful sounds.
"I think that it's about time we get out there, start tickling the dogs and the cats, and the pigs, the rats, as well as the chimpanzees," Provine says. "I think we'll learn a lot about what we have in common, as well as our differences."
Can't you just see me as an Animal Tickler?