I found this article on a 'Fox News' report from 2006 :
What is Laughter, and Why Do We Do It?
It made the following points :
* We hear laughter every day. Nothing could be more common. However, just because it’s common doesn’t make laughter any less strange.
* Why do we do it? The answer may seem obvious: We laugh when we perceive something to be funny. But the obvious answer is not correct, at least most of the time.
* “Most laughter is not in response to jokes or humor,” says Robert R. Provine,
Professor of Psychology and Neuroscience at the University of Maryland.
* He argues that in humans, laughter predates speech by perhaps millions of years and before our human ancestors could talk to each other it was a simpler method of communication.
* Steve Wilson, a Psychologist and 'laugh therapist' argues that it is instinctual : “Infants laugh almost from birth and the blind and deaf still laugh. Humans are hardwired for laughter.” He calls himself a 'joyologist'and teaches people, business groups, and aspiring laugh therapists how to laugh.
* Laughing Is Contagious. Seeing someone in hysterics, even if you don’t know who the person is or why she’s laughing, can set you laughing too. Why?
* The answer lies in the evolutionary function of laughter as a 'social' and not a 'solo' activity. Provine says : “We laugh 30 times as much when we’re with other people than we do when we’re alone."
* The purpose of a laugh could be to trigger positive feelings in others. When we laugh, the people around us might start laughing in response. Soon, the whole group is cheerful and relaxed. Laughter can ease tension and foster a sense of group unity. This could have been particularly important for small groups of early humans.
If all this is the case, then it is more and more important that more and more old men laugh more and more and to start the ball rolling try this old 'game show' contestant from the U.S.A. I have seen this clip of 'Uncle Joe' many times and it still makes me laugh :