A. To find out where laughter comes from, scientists studied chimpanzees - they make a noise which is similar to laughter when they are tickled or playing. Because apes have this primitive form of laughter, it's assumed that laughter came along before language, and that we have been laughing for about six million years.
Q. Why did it develop
A. The theory is that laughter evolved as a signal to reassure others in a group that there is no danger. It's possible that its use could have been even more precise, perhaps as signal that tickling or play fighting were not serious and were intended to be safe and non-threatening. Even now, human laugh when play wrestling or tickling each other.
Q. So laughter developed before anyone was able to tell a joke
A. That's right. Tickling is the first way we had to stimulate laughter, and it still works. Humour evolved more recently. Robert Provine, professor of psychology at the University of Maryland, is one of the world's leading authorities on laughter. He has studied people laughing in shopping centres, schools, offices and parties for 20 years, and he believes that less than 20% of laughter is linked to humour.
Q. How many times a day do we laugh on average
A. It's been averaged at 18 times a day, but that can vary enormously, and children, of course, will laugh more than adults. We're 30 times more likely to laugh or smile when we're with other people than when we're on our own.
Q. Why do we laugh at jokes
A. It can partly be explained by differences in the brain. A joke is recognised to have two halves - one sets up the tension and the incongruity and the other resolves it with a punchline.
It has been found that if there is damage to the right side of the brain - which deals with emotions - sufferers see any incongruity as funny and laugh too much and at the wrong things. However, if there is damage to the left side of the brain - the logical side - sufferers don't understand the incongruity and are far too serious. This suggests that the brain produces humour when the left side recognises the incongruity in a joke, and the right side - better at understanding the overall picture rather than logical detail - resolves the anomaly. In other words, the left side 'sets up' the joke and the right side 'gets it'.
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By Sheena Miller