Thirty years ago, human happiness seemed like a pretty unserious subject for scientific study. These days positive psychology, as happiness research is known, is de rigeur. Oscar-nominated filmmaker Roko Belic ("Genghis Blues") explores the science of contentment in his latest doc, "Happy." Belic traveled to five continents, talking to researchers, comparing the state of satisfaction in various countries and finding some very jolly people. Does happiness depend on our material conditions? Just how much control do we have over our own sense of well-being? And whence the intellectual prejudice that happiness lacks gravitas?