Rats and Monkeys Laugh

It may sound strange, but several scientists have elicited "tickle-induced vocalizations" from primates. Penny Paterson, president of the Gorilla Foundation says that Koko, the gorilla famous for her sign language abilities, even had a special "ho, ho," for visitors she liked. And rats apparently have very ticklish necks. When Bowling Green State University scientist Jaak Panksepp and his graduate students tickled baby rats' napes, the rodents emitted high-frequency chirps that Panksepp interpreted as laughter.

Robert Levinson, psychology professor at the University of California Berkeley, invited couples into his lab and asked each partner to discuss something that irritated him or her about the other partner. The couples who tackled the stressful situation with laughter not only felt better in the moment, but had higher levels of relationship satisfaction and stayed together longer than couples who did not crack a smile.

When you see people laughing, you just can't help but smile. That is because your brain makes it nearly impossible not to. That is the result of research from the lab of Sophie Scott, a neuroscientist at University College London. When she monitored subjects' brains while she played laughing sounds, she found that the premotor cortical region of the brain, which prepares the muscles in the face to move, was activated.

Incidentally, 10 to 15 minutes of laughing a day can burn up to 40 calories, according to a Vanderbilt University study. Researchers determined that the increase in heart rate and oxygen consumption during these funny moments boosted the burn.