Chuck Bednar for redOrbit.com – @BednarChuck
Humans aren’t the only members of the animal kingdom that enjoy having their funny bones tickled, as studies have shown that both rodents and primates are known to get the giggles, and that chimpanzees produce “laughing faces” even when they are silent.
The topic of animal laughter came up over the weekend as the result of a question submitted by a reader to National Geographic, which simply wondered whether or not animals laughed. As it turns out, scientists have long been investigating the same thing, as research into expressions of humor date back at least to a study involving rats that was published in 2000.
In that paper, Washington State University psychologist and neuroscientist Jaak Panskepp found that rodents who were tickled made a happy, chirping-like noise similar to those they emit during play. The noise is inaudible to the human ear, but apparently some of the creatures enjoyed being tickled so much that they would actually follow the researchers’ hand around.
In the years that followed, Panskepp and colleagues went on to identify brain circuits involved in laughter in rats that can be used to study human emotion, the website added. His work has helped in the development of an antidepressant for humans that is currently in clinical trials.
Like humans, chimps can laugh and convey emotions silently
Six years ago, University of Portsmouth psychologist Marina Davila Ross conducted a series of experiments in which she tickled infant and juvenile orangutans, gorillas, and chimps and found that primates responded with “tickle-induced vocalizations” similar to laughter, Nat Geo said. That research was published in the journal Current Biology.
Now, Ross has published a new paper in the journal PLOS One which demonstrates that chimps have a special “laugh face” in which they smile with their teeth bares, whether they are laughing at the time or not. This discovery, she explained, reveals that the creatures can communicate in a variety of explicit, versatile ways and can convey emotion silently, similar to humans.
“Chimpanzees, like humans, can produce their facial expressions free from their vocalizations,” she told Discovery News. “This ability is important for humans. For instance, it allows us to add a smile while talking or laughing, and we can also produce smiles silently. Until now, we did not know that non-human primates also have this ability.”
As for laughter, Ross noted that while the sounds produced by chimps are not identical to those produced by humans, they are largely unmistakable. Her findings, the website added, appear to indicate that the ability to laugh and the related facial expressions may have originally emerged in the last common ancestor of humans and chimps.
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