Whether it's live on the Smithsonian National Zoo's panda cam or in front of a crowd, possibly no other animal's sex life is as closely watched as the giant pandas' is. And there's a reason. These cuddly-looking black and white bears just can't figure out how to mate. But, with a little help from science, the once-endangered giant panda is making a comeback. To honor the arrival of the National Zoo's newest giant pandas, we peep into the (not so secret) sex lives of pandas. Guests: Pierre Comizzoli, panda sex expert and staff scientist at the Smithsonian Conservation Biology InstituteLisa Stevens, AKA “Panda Lady”; former senior curator of mammals at the Smithsonian’s National ZooStephen Powers, panda fan