Research suggests that we humans aren't the only animals prone to fits of laughter (or something akin to laughter, that is) if someone tickles us in all the right spots. In fact, playful tickling behaviors have been observed between primates like chimpanzees, bonobos, and gorillas. Scientists have also conducted experiments where they, themselves, tickled animals including rats and dogs, and their findings have shown that some animals may actually be induced to laugh via touch. If this topic tickles your fancy, then please read on!
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The Two Types of Tickly
Before delving into the research, it's helpful to understand that scientists distinguish between two types of ticklishness: knismesis and gargalesis. Knimesis refers to that feeling (usually not very pleasant) that you get when a feather is run across the sole of your foot or if an ant is marching up your arm. And now that we've told you what knimesis refers to, you've probably already guessed what the second type of ticklishness—gargalesis—is. Yup, it's that odd thing that causes a person to be reduced to hysterics when they're touched in sensitive areas like their underarms, sides, or other "ticklish" spots. The researchers of these studies we mention here are more concerned with gargalesis-induced laughter, as it's the ticklishness closely associated with what scientists refer to as "social joy."
"Haha," vs. "Huh Huh," vs. "Chirp Chirp," vs...
An obvious problem with studying ticklishness and laughter among animals is that the laughter of the particular species being observed (according to the researchers' definition of laughter, that is) may sound nothing at all like human laughter—so how would you recognize it? To overcome this hurdle, scientists have had to compare the vocalizations animals made while being tickled with those they made when they engaged in other, obviously pleasurable activities. If they were the same, they could then draw a connection between these particular vocalizations and feelings of joy—particularly, socially-induced joy. Using this technique, researchers at the College of Veterinary Medicine at Washington State University concluded that rats, in fact, are ticklish and their laughter consisted of high pitched chirps inaudible to the human ear. (Watch this super cute video of the ticklish rats!) Chimpanzees have been observed tickling each other while playing and their laughter sounds like heavy breathing, panting, or grunting. However, some research suggests that gorilla laughter, unlike chimp laughter, can at times sound very similar to human laughter.
Titters Without Tickles?
It's also important to note that if a certain animal is thought to engage in laughter, that doesn't automatically mean that the animal is also ticklish. That is, you can't assume that laughter can be induced by tickling them. Also, if you "tickle" your dog, cat, or any other animal and they emit noises that may sound like laughter, you can't automatically assume those vocalizations are, in fact, "laughter." While we're on the subject of dog laughter, though, recent evidence suggests that dogs do, indeed, laugh—that is, emit sounds associated with feelings of social joy. According to researchers, dog laughing sounds a bit like a voiceless pant: "huh huh huh." Whether we can tickle actual laughs out of our canine pals, though, has yet to be seen, although many dogs definitely have sensitive spots that they enjoy having rubbed and scratched (evidenced by the way they'll kick their hind leg in approval!). Videos abound online of a number of animals being "tickled" into making some jolly-sounding noises including dolphins, dogs, meerkats, and penguins. However, more research will have to be conducted before concluding that ticklishness is a trait we share with these species.
By Maya M.