Guests: Allen Young Author, "The Chocolate Tree" (Smithsonian Institution Press) Curator, Zoology Vice President, Collections, Research and Public Programs Milwaukee Public Museum Milwaukee, Wisconsin Dave Prybylowski Manager, Chocolate Research M & M Mars Elizabethtown, Pennsylvania Russell Greenberg Director Smithsonian Migratory Bird Center Washington, DC Valentine's Day has come and gone, and so have enormous quantities of chocolate. The average American consumes five pounds of chocolate every year. But there's more to the sweet stuff than meets the eye. Between the time the cacao flower is pollinated and the time you pop that truffle into your watering mouth, a whole lot of biology and even some chemistry goes on. In this hour, we'll look at the science of chocolate.