Don't Laugh: Just Think About It Live Science - April 1, 2006
Laughing helps arteries and boosts blood flow - New Scientist - March 10, 2005
Laughing appears to be almost as beneficial as a workout in boosting the health of blood vessels, a new study suggests.
"Thirty minutes of exercise three times a week and 15 minutes of hearty laughter each day should be part of a healthy lifestyle," says Michael Miller of the University of Maryland Medical Center in Baltimore, US, whose team has shown that laughter relaxes arteries and boosts blood flow.
He showed clips from the comedy movie King Pin to 20 volunteers. Before and afterwards, he made ultrasound measurements of blood flow and dilation in the brachial artery in the arm. The scans showed that in all but one of the volunteers, the volunteers' arteries relaxed and blood flowed more freely than usual for 30 to 45 minutes after the film.
The opposite happened when the same people watched harrowing scenes from the war movie Saving Private Ryan. In 14 of the 20 volunteers, the artery wall constricted, reducing blood flow. Overall, blood flow decreased by 35% after the stressful clips and increased by 22% during laughter.
The results suggest that laughter could help keep the lining of the arteries - the endothelium - healthy and thus reduce the risk of cardiovascular disease. "At the very least, laughter offsets the impact of mental stress, which is harmful to the endothelium," Miller says.
December 4, 2003 - Nature
Humor tickles drug centre that gives hedonistic high. There's truth in the maxim 'laughter is a drug'. A comic cartoon fired up the same brain centre as a shot of cocaine, researchers are reporting.
A team at Stanford University in California asked lab mates, spouses and friends to select the wittiest newspaper cartoons from a portfolio. They showed the winning array to 16 volunteers while peering inside their heads by functional magnetic resonance imaging (fMRI).
The cartoons activated the same reward circuits in the brain that are tickled by cocaine, money or a pretty face, the neuroscientists found1. One brain region in particular, the nucleus accumbens, lit up seconds after a rib-tickler but remained listless after a lacklustre cartoon.
The nucleus accumbens is awash with the feelgood chemical dopamine. The region's buzz may explain the euphoria that follows a good joke, the team suggests. "Intuitively, it makes sense," agrees Bill Kelley, who studies humour at Dartmouth College in Hanover, New Hampshire.
Earlier investigations found that humour triggers brain regions that work out a joke's language and meaning, or those that control smiling and laughter. Kelley, for example, has studied people's brains while they watched episodes of television comedies Seinfeld and The Simpsons. "It's surprising it's not consistent," he says.
A powerful fMRI machine and a particularly detailed analysis may explain why the new study picked up activity in the reward areas as well, suggests lead researcher Allan Reiss.
Reiss hopes that the finding could help to diagnose the early stages of depression - or show whether antidepressants are taking effect - during which people's appreciation of humour is altered. "That would be a terrific way to use this type of work," he says.
October 7, 2003 - Discovery
Laughter may pre-date human evolution
The special sounds and gestures made by infant bonobos also known as pygmy chimpanzees when they are tickled suggest that the origins of laughter may pre-date human evolution, according to a new report.
A study of a young bonobo in a German zoo found that when it was tickled it combined vocalizations and facial gestures much like those made by human infants, said the report in the BioMednet science news service.
The finding suggests that the rules for how emotion is encoded behaviorally were laid down in the common ancestor humans shared with other great apes, Elke Zimmermann of the Institute of Zoology at the Tieraerztliche Hochschule, in Hanover, told a recent conference of the German Primate Society.
The sounds made by the bonobo when tickled during its first year of life were carefully recorded at Wuppertal Zoo eight years ago by another researcher, Birgit Förderreuther, who was unable to continue the study due to illness, the report said.
Now Zimmerman has conducted a sophisticated analysis of the recordings and compared them with sounds made by human babies when they are tickled.
She found that the bonobo's vocalizations followed broadly the same spectrographic pattern — a technique that depicts the changes in frequency and intensity of the sound over time — as that of human infants, except that the bonobo's laugh was at higher frequencies.
Infant bonobos and humans both combine those sounds with a facial gesture known as a "relaxed open-mouth display."
Zimmerman believes that her findings confirm a hypothesis that laughter originated in primates, as a universal signal of wellbeing in a playful situation to help regulate social interactions, the report said.
"A pre-human evolutionary origin for laughter could also explain why it is still present in deaf and blind infants, and why it fulfils the same role — and sounds the same — in people from different cultures," it said.
Laughter is well documented in common chimpanzees, with observations of both wild and captive chimpanzees revealing that they even share with humans the same ticklish anatomical regions — the armpits and belly.
Chimpanzee laughter, however, involves a more rapid panting action with sound made on both inhalation and exhalation of air. Human laughter tends to involve sound made mainly on exhalation.
Chimpanzees are also known to continue enjoying tickling well into adulthood. Among young chimpanzees that have been taught sign language, tickling is a frequent topic of conversation, according to a recent article on the biology of laughter in Discover magazine.
But chimpanzee laughter usually happens in a different social context than it does in humans: chimps laugh almost exclusively during physical contact, or when contact is imminent during chasing and wrestling games, whereas most adult human laughter occurs during conversation without touching being involved, according to Robert Provine, a psychologist at the University of Maryland, who is an authority on laughter.
Why do we laugh? - July 2002 - MSNBC
Laughter is part of the universal human vocabulary. All members of the human species understand it. Unlike English or French or Swahili, we donıt have to learn to speak it. Weıre born with the capacity to laugh.
One of the remarkable things about laughter is that it occurs unconsciously. You don't decide to do it. While we can consciously inhibit it, we donıt consciously produce laughter. Thatıs why itıs very hard to laugh on command or to fake laughter. (Donıt take my word for it: Ask a friend to laugh on the spot.)
Laughter provides powerful, uncensored insights into our unconscious. It simply bubbles up from within us in certain situations.
Very little is known about the specific brain mechanisms responsible for laughter. But we do know that laughter is triggered by many sensations and thoughts, and that it activates many parts of the body.
When we laugh, we alter our facial expressions and make sounds. During exuberant laughter, the muscles of the arms, legs and trunk are involved. Laughter also requires modification in our pattern of breathing.
We also know that laughter is a message that we send to other people. We know this because we rarely laugh when we are alone (we laugh to ourselves even less than we talk to ourselves).
Laughter is social and contagious. We laugh at the sound of laughter itself. Thatıs why the Tickle Me Elmo doll is such a success - it makes us laugh and smile.
The first laughter appears at about 3.5 to 4 months of age, long before we're able to speak. Laughter, like crying, is a way for a preverbal infant to interact with the mother and other caregivers.
Contrary to folk wisdom, most laughter is not about humor; it is about relationships between people. To find out when and why people laugh, I and several undergraduate research assistants went to local malls and city sidewalks and recorded what happened just before people laughed. Over a 10-year period, we studied over 2,000 cases of naturally occurring laughter.
We found that most laughter does not follow jokes. People laugh after a variety of statements such as "Hey John, where ya been?" "Here comes Mary," "How did you do on the test?" and "Do you have a rubber band?" These certainly arenıt jokes.
We donıt decide to laugh at these moments. Our brain makes the decision for us. These curious "ha ha ha's" are bits of social glue that bond relationships.
Curiously, laughter seldom interrupts the sentence structure of speech. It punctuates speech. We only laugh during pauses when we would cough or breathe.
An Evolutionary Perspective
We believe laughter evolved from the panting behavior of our ancient primate ancestors. Today, if we tickle chimps or gorillas, they don't laugh "ha ha ha" but exhibit a panting sound. That's the sound of ape laughter. And itıs the root of human laughter.
Apes laugh in conditions in which human laughter is produced, like tickle, rough and tumble play, and chasing games. Other animals produce vocalizations during play, but they are so different that it's difficult to equate them with laughter. Rats, for example, produce high-pitch vocalizations during play and when tickled. But it's very different in sound from human laughter.
When we laugh, we're often communicating playful intent. So laughter has a bonding function within individuals in a group. It's often positive, but it can be negative too. There's a difference between "laughing with" and "laughing at." People who laugh at others may be trying to force them to conform or casting them out of the group.
No one has actually counted how much people of different ages laugh, but young children probably laugh the most. At ages 5 and 6, we tend to see the most exuberant laughs. Adults laugh less than children, probably because they play less. And laughter is associated with play.
We have learned a lot about when and why we laugh, much of it counter-intuitive. Work now underway will tell us more about the brain mechanisms of laughter, how laughter has evolved and why we're so susceptible to tickling - one of the most enigmatic of human behaviors.
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