Scientists at the University of Portsmouth, England, are now shedding some light on the origins of laughter. Marina Davila Ross, head of the research, recorded human baby laughs and analyzed them in comparison to sounds great apes make when they are tickled, thereby revealing the roots of laughter.
You can learn more about it, view and hear apes laughing at the links below.
"Tickling Apes Reveals Laughter's Origins" - usnews.com
"Tickled apes yield laughter clue" - bbc news
"Apes Laugh, Tickle Study Finds" - national geographic news.