As the childhood song goes, "If you're happy and you know it, then your face will surely show it," but do you ever truly wonder why you're happy? Have you thought about where our emotions come from and why they make us feel the way we do? A panel of Harvard faculty members whose research sheds light on the range of human emotion will explore the science behind the smiles and tears during this March 20, 2012, seminar. Learn more about the Longwood Seminars by visiting hms.harvard.edu/public/longwood.