Tickling
 Q: What causes tickling?
Why can't we tickle ourselves? (LMA, Albuquerque, New Mexico)
A tickling session. In the laboratory setting, Panksepp lets the rats roam freely and
does not hold them while tickling. Photo by FutureWatch/Harvey Mudd
College.
A: The reasons why people are ticklish may go back a long, long way. Tickling may have been one of the first ways early
humans showed that they liked each other. It's a form of non-verbal communication. Also being ticklish let's you know if
something is crawling on you.
Darwin was the first to point out that a tickling victim squirms and strains to withdraw the tickled part, to get away from
attacks on vulnerable areas such as the soles of the feet, armpits, belly and flank. If a fly settles on a horse's belly, the horse ripples his skin muscles as a tickled
child squirms. But he doesn't laugh.
Children don't always either. "The child will laugh only--and this is the crux of the matter--when it perceives tickling as a mock attack, a caress in mildly
aggressive disguise," says the Encyclopedia Britannica.
Tickling perception happens in the cerebral cortex, a higher-function part of the brain. The cerebellum, a primitive part of the brain, dampens the tickle sensation
when you tickle yourself by telling the cortex to ignore the sensation, says Sarah-Jayne Blakemore, cognitive neuroscientist at London's Institute of Neurology,
who has concluded a study of the matter and reported her findings in the November 1998 issue of Nature Neuroscience.
By the way, ours is not the only species that laughs and responds to tickling. Jaak Panksepp and Jeffrey Burgdorf, neuroscientists at Bowling Green State
University in Ohio, just concluded a study of rats. "We tickle rats just the way you would a young child," says Panksepp in recent email. They chirp, kick their
feet, and get excited--they're especially ticklish about the nape of the neck, he says.
Updated June 7, 2009 The Evolution of Primate Laughter...
The Associated Press reported on June 4th that "When scientists set out to trace
the roots of human laughter, some chimps and gorillas were just tickled to help.
Literally. That's how researchers made a variety of apes and some human babies
laugh.
"After analyzing the sounds, they concluded that people and great apes
inherited laughter from a shared ancestor that lived more than 10 million years
ago. Experts praised the work. It gives very strong evidence that ape and human
laughter are related through evolution, said Frans de Waal of the Yerkes
National Primate Research Center at Emory University in Atlanta.
"Marina Davila Ross of the University of Portsmouth in England
and colleagues carried out a detailed analysis of the sounds evoked by tickling
three human babies and 21 orangutans, gorillas, chimps and bonobos. After
measuring 11 traits in the sound from each species, they mapped out how these
sounds appeared to be related to each other.
"The result looked like a family
tree. Significantly, that tree matched the way the species themselves are
related, the scientists reported online Thursday in the journal Current Biology.
They also concluded that while human laughter sounds much different from the ape
versions, its distinctive features could well have arisen from shared ancestral
traits. ..."
Source:
http://www.google.com/hostednews/ap/article/ALeqM5jfB2AF8qLQ4OJB68gLRKRxfZYsoQD98JUVEG0
Further Surfing:
"Tickling rats brings out rodent joy and childlike laughter" by Randy Ringen, FutureWatch
"Beyond a joke", Horizon, BBC online
"Teach an infant to love learning" by Kathleen Fackelmann, USA TODAY
Jaak Panksepp, Distinguished Research Professor Emeritus of Psychology, Bowling Green State University, Ohio
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