In the Season 6 premiere, 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."