See the film that helped launch the laughter movement. Laughology is both the first feature documentary about laughter and a comical odyssey through the gravity and seriousness of modern times. When Albert Nerenberg has an encounter with death, he realizes laughter is the antidote. As he searches for the reasons behind the contagiousness of laughter he discovers that laughter is far more than he imagined. The original peace signal, the sound that opens the door to play, he encounters the founder of Laughter Yoga, The Man with the Most Contagious Laugh in the World and an entirely new way to laugh. What results is nothing less than a "tour de force" Hour Magazine and a "gem" Leonard Maltin. 
If you see one movie about the origins of laughter, this is it. Well currently you have no choice.