WHAT IS LAUGHTER AND WHY DO WE DO IT?

We hear laughter every day. Nothing could be more common. But just because it's common doesn't make laughter any less strange. Do animals laugh? The answer is yes, after a fashion. "Most laughter is not in response to jokes or humor," says Robert R. Provine, a professor of psychology and neuroscience at the University of Maryland Baltimore County. In a survey of 1,200 "laugh episodes," he found that only 10%-20% of laughs were generated by anything resembling a joke. The other 80%-90% of comments that received a laugh were dull non-witticisms. In humans, laughter predates speech by perhaps millions of years. Before our human ancestors could talk with each other, laughter was a simpler method of communication. Infants laugh almost from birth. So we know it's not a learned behavior. Humans must be hardwired for laughter.

Why does hearing other people laugh make us more likely to laugh ourselves? Laughter is social; it's not a solo activity, according to a 2005 article published in the Quarterly Review of Biology.The purpose of a laugh could be to trigger positive feelings in other people. Laughter can ease tension and foster a sense of group unity. To account for the differences, some researchers divide laughter into two groups. The first includes spontaneous laughter. The other group includes laughter that is less spontaneous: it includes fake laughter, nervous laughter, and other social laughter that is unconnected to humor.They actually have different origins in the brain. The spontaneous laughter originates in part from the brain stem, an ancient part of the brain. So it might be a more original form of laughter. The other type of laughter comes from parts of the brain that developed more recently, in evolutionary terms. While humans might fancy themselves as the only animal capable of laughter, evidence suggests otherwise. In fact, apes seem to laugh, after a fashion.

The ha-ha noise of human laughter ultimately has its origins in the ritualized panting laughter of our primate ancestors. Some researchers have found laugh-like behavior in other animals, even in the rat. But in some people with underlying health conditions, occasionally, jokes can kill. And according to many anecdotal reports, laughter is a panacea that will heal your immune system, dull your pain, improve your memory, lower blood pressure, and perform other wondrous feats. So laugh and the world laughs with you.