Animals Enjoy A Good Laugh, Too, Say Scientists
By Peter Gorner - Chicago Tribune Science Reporter - 2 April
2005
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/local/
|
