NOVA scienceNOW: What Makes Us Human?

David Pogue examines the evolutionary roots of those traits that separate humans from other species. He also investigates what may have happened to the Neanderthals and undergoes a test to see if he has any Neanderthal DNA. Also: the story of Ethiopian paleoanthropologist Zeresenay Alemseged, who discovered the fossil bones of Selam, a 3.3 million-year-old human ancestor who is often called "Lucy's baby."