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Home > Archive > Medicine laboratory > April 2005 > Animals Enjoy A Good Laugh, Too, Say Scientists
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Animals Enjoy A Good Laugh, Too, Say Scientists
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Animals Enjoy A Good Laugh, Too, Say Scientists
By Peter Gorner
Chicago Tribune Science Reporter
4-2-5
Tickling rats to make them chirp with joy may seem frivolous as a
scientific pursuit, yet understanding laughter in animals may lead to
revolutionary treatments for emotional illness, researchers suggest.
Joy and laughter, they say, are proving not to be uniquely human traits.
Roughhousing chimpanzees emit characteristic pants of excitement,
their version of "ha-ha-ha" limited only by their anatomy and lack
of breath control, researchers contend.
Dogs have their own sound to spur other dogs to play, and
recordings of the sound can dramatically reduce stress levels in
shelters and kennels, according to the scientist who discovered it.
Even laboratory rats have been shown to chirp delightedly above
the range of human hearing when wrestling with each other or being
tickled by a keeper--the same vocalizations they make before
receiving morphine or having sex.
Studying sounds of joy may help us understand the evolution of
human emotions and the brain chemistry underlying such emotional
problems as autism and attention-deficit/hyperactivity disorders,
said Jaak Panksepp, a pioneering neuroscientist who discovered
rat laughter.
Panksepp, of Bowling Green State university in Ohio, sums up
the latest studies in this week's edition of the journal Science in
hopes of alerting colleagues to results that he terms "spectacular."
The research suggests that studying animal emotions, once a
scientific taboo, seems to be moving rapidly into the mainstream.
"It's very, very difficult to find skeptics these days. The study
of animal emotions has really matured.
Things have changed completely from as recently as five years
ago," said Mark Bekoff, an expert in canine play behavior and
professor of biology at the university of Colorado, Boulder.
Biologists suggest that nature apparently considers sounds of
joy important enough to have conserved them during the
evolutionary process.
"Neural circuits for laughter exist in very ancient regions of the
brain," Panksepp said, "and ancestral forms of play and laughter
existed in other animals eons before we humans came along."
Research in this area "is just the beginning wave of the future,"
said comparative ethologist Gordon Burghardt, of the University
of Tennessee, who studies the evolution of play. "It will allow us
to bridge the gap with other species."
New investigative techniques often rely on super high-tech
scanning wizardry, but the most important tool for scientists in
this field is much more simple.
"Tickles are the key," Panksepp said. "They open up a previously
hidden world."
Panksepp had studied play vocalizations in animals for years
before it occurred to him that they might be an ancestral form
of laughter.
"Then I went to the lab and tickled some rats. Tickled them
gently around the nape of their necks. Wow!"
The tickling made the rats chirp happily--"as long as the animal's
friendly toward you," he said. "If not, you won't get a single chirp,
just like a child that might be suspicious of an adult."
Rats that were repeatedly tickled became socially bonded to
the researchers and would seek out tickles. The researchers
also found that rats would rather spend time with animals that
chirp a lot than with those that don't.
During human laughter, the dopamine reward circuits in the brain
light up. When researchers neurochemically tickled those same
areas in rat brains, the rats chirped.
Rat humor remains to be investigated, but if it exists, a prime
component will be slapstick, Panksepp speculated. "Young rats,
in particular, have a marvelous sense of fun."
Panksepp said that laughter, at least in response to a direct
physical stimulus such as tickling, may be a common trait
shared by all mammals.
Psychologist and neuroscientist Robert Provine, author of
"Laughter: A Scientific Investigation," tickled and played with
chimpanzees at the Yerkes Regional Primate Center in Atlanta
while researching the origins of the human laugh.
Laughter in chimps, our closest genetic relatives, is associated
with rough-and-tumble play and tickling, Provine found. That
came as no surprise.
"It's like the behavior of young children," said Provine, of the
University of Maryland Baltimore County. "A tickle and
laughter are the first means of communication between a
mother and her baby, so laughter appears by about four months
after birth."
The importance of such an early behavior is apparent.
"We're talking about a life-and-death deal here--the bonding
and survival of babies," Provine said.
When chimps laugh, they make unique panting sounds, ranging
from barely audible to hard grunting, with each inward and
outward breath.
"We humans laugh on outward breaths. When we say `ha-ha-ha,'
we're chopping an outward breath," Provine said. "Chimps can't
do that. They make one sound per inward and outward breath.
They don't have the breath control to ... make the traditional
human laugh."
The breakthrough in dog laughter was accomplished by
University of Nevada, Reno, researcher Patricia Simonet
while working with undergraduates at Sierra Nevada College
in Lake Tahoe.
With extensive chimp research behind her, Simonet was
open to the idea of animal emotions, but the laughing sound
she discovered in dogs was unexpected: a "breathy,
pronounced, forced exhalation" that sounds to the untrained
ear like a normal dog pant.
But a spectrograph showed a burst of frequencies, some
beyond human hearing. A plain pant is simpler, limited to
just a few frequencies.
Hearing a tape of the dog laugh made single animals take up
toys and play by themselves, Simonet said. It never initiated
aggressive responses.
"If you want to invite your dog to play using the dog laugh,
say `hee, hee, hee' without pronouncing the `ee,'" Simonet
said. "Force out the air in a burst, as if you're receiving the
Heimlich maneuver."
When she played a recording of a laughing dog at an animal
shelter, Simonet found that even 8-week-old puppies reacted
by starting to play, something they hadn't done when exposed
to other dog sounds.
"Some sounds, like growls, confused the puppies. But the
dog laugh caused sheer joy and brought down the stress
levels in the shelter immediately."
http://www.chicagotribune.com/news/...ack=1&cset=true
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