Fundamentals Of Fun

Studying vocalizations of animals at play may aid research on human laughter and joy

Newsday, 02-11-2002, pp D06.

By Madeline Bodin.

IT WAS PLAYTIME at Pet Network, a no-kill animal shelter on the Nevada shore of Lake Tahoe. The dogs had thoroughly sniffed the room. The dog toys were in reach. The humans were waiting. The video camera was ready.

The computer was booted up. The recorded sound of dog "laughter" filled the air.

This was not a typical romp at the animal shelter. It was another episode in the surprisingly serious business of researching animal laughter.

After hearing the recording, most of the dogs bowed to another dog in the room in a recognized dog behavior called a "play bow." Some then grabbed a ball and brought it to another dog, while others wrestled or gently pawed their canine companions.

One 7-month-old dog took a toy and began playing catch alone and dog-laughing. He did not approach the other dogs in the room.

Last winter and spring, Patricia Simonet, who has taught animal behavior at Sierra Nevada College in Lake Tahoe, and two undergraduate researchers studied a specific sound that dogs make while playing and that spurs dogs to play when they hear it. The researchers are confident in calling that sound a laugh, even though it sounds nothing like human laughter.

"Referring to the vocalization as a laugh was a decision I did not take lightly," says Simonet. "I hesitated because of the dreaded curse, being accused of anthropomorphism."

The concept of animal laughter is controversial among scientists. Many scientists say that the evidence of laughter in animals is yet to be found. But Simonet is not alone in characterizing an animal vocalization as laughter. Previous research has described laughter in chimpanzees and rats.

"Some people think this research into laughter is frivolous," says Jaak Panksepp, the neurobiologist who discovered rat laughter, "but finding the neurobiological components of joy is, or should be, among the most important areas for neurobiological research."

The laughter of chimpanzees may prove to be the Rosetta stone of animal laughter research. Robert R. Provine, a professor at the University of Maryland, Baltimore County, and author of "Laughter: A Scientific Investigation," says that chimps make one breathy, panting sound with each inhalation and exhalation when they laugh - which young chimps often do while playing, and especially while being tickled.

Humans, he explains, chop that exhalation sound into the familiar "ha, ha, ha."

"Chimpanzees don't make a sound during exhalation. Humans do," says Provine. "That observation is the bridge between human and animal laughter."

Simonet has extensive experience studying chimp behavior and has heard chimp laughter first-hand. This may have helped her recognize dog laughter when she heard it, she says, but the idea in Charles Darwin's book "The Expression of the Emotions in Man and Animals" that the expression of a similar emotion in two different animal species would be neither exactly the same nor abruptly different, was the key to her finding.

Panksepp, head of affective neuroscience research at the Chicago Institute for Neurosurgery and Neuroresearch and professor emeritus at Bowling Green State University, discovered that the rats he worked with chirped at a particular frequency above human hearing during rough-and-tumble play.

"At first we just called it a play vocalization," he says. "But then we did some experiments with tickling, and lo and behold this chirping comes out higher than ever." He considered that because this sound was associated with tickling, it could be called laughter, but he kept researching it.

"We didn't go out on this limb of calling it laughter on the basis of one experiment," he says. "Our neuroscience colleagues can be rather harsh."

Since then Panksepp has done "an enormous number" of experiments on rat laughter. Among the things he has discovered is that rats make this particular chirp only when everything is going well. If there is anything negative, such as a whiff of cat odor on the researcher's tickling hand, the rat will not chirp. Informally, Simonet has noticed the same thing about the sound she calls a dog laugh.

This sound, described by Simonet as a "breathy, pronounced, forced exhalation," can be difficult to distinguish from a regular dog pant for the untrained ear. A spectrograph analysis showed Simonet the difference, however. On the spectrograph, a dog laugh shows a burst of sound frequencies, some above human hearing, while the plain pant is narrower, hitting just a few frequencies.

You can hear Simonet's recording of a dog laugh and a pant at: www.sierranevada.edu/academic/science/ laughingdog.html.

Simonet can do a fair imitation of a dog laugh herself. The spectrograph of her imitation doesn't hit all the same frequencies, but dogs seem to get the idea.

"When I do this to dogs on the street, they give me that same look you get from a French tourist who suddenly discovers that you spoke French all along," she says.

If you want to invite your favorite dog to play using the dog laugh, say "hee, hee, hee" without pronouncing the "ee," Simonet suggests: "Force the air out in a burst, like someone's giving you the Heimlich maneuver."

Simonet's research has practical applications for dog owners who want to communicate with their dogs, but it may also contribute to the study of play and the study of the evolution of human laughter. Marc Bekoff, an animal play behavior expert, professor at the University of Colorado and a former resident of Lynbrook and Roslyn, wants to see more research before he calls the sound a dog laugh, but he is impressed by what Simonet has done so far.

"Patricia's work forces us to go into more detail about dog vocalization, " he says. "She has opened up our eyes to the fact that these vocalizations might be very important in play."

Another animal play expert, Gordon M. Burghardt of the University of Tennessee, Knoxville, says that scientists already recognize animal behaviors, such as a play bow and a play face, that solicit play. "I have a gut feeling that laughing plays a similar role. Human laughter is protean. It has evolved to fit a lot of functions, but it has its origins in play."

"Laughter is not an arbitrary sound that symbolizes play," says Provine.

"The 'ha ha ha' sound humans make when we laugh mimics the panting, labored breathing of rough-and-tumble play."

Provine says the study of animal laughter has already contributed to the study of the evolution of language in humans. "Chimpanzees and other great apes don't have sufficient breath control to laugh - or speak," he says. Understanding why chimps don't laugh out loud also explains why they can't speak. "Laughter is a tool to study vocal evolution."

Panksepp sees his research into rat laughter and the neurobiology of joy as leading to new antidepressant medications that enhance positive feelings, instead of simply moderating negative feelings as today's most popular antidepressant medications do.

In her experiments at the animal shelter, Simonet and her colleagues found that even their youngest subjects, 8-week-old puppies, reacted by playing when they heard a recording of a dog laugh, something the puppies didn' t do when they heard other dog sounds.

"For the play laugh, the puppies - the young ones especially - were right into it, playing with the ball and making play bows," says Simonet. She believes this may show that laughter is innate in dogs, and perhaps in other animals too.

"Laughter seems to be an ancestral, ancient behavior," says Panksepp.

We don't know yet whether the laughter observed in rats, dogs and chimps reflects an untutored type of laughter similar to what is found in human babies, he notes. But if it is, the study of animal laughter might not only give us interesting information about our animal companions, but help us understand ourselves as well.

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