Dr Alice Roberts travels the globe to discover the incredible story of how humans left Africa to colonise the world - overcoming hostile terrain, extreme weather and other species of human. She pieces together precious fragments of bone, stone and new DNA evidence and discovers how this incredible journey changed our African ancestors into the people we are today.
This week, for Stone Age people, reaching North & South America seems impossible: On each side, vast oceans and to the north, an impenetrable ice sheet that covered the whole of Canada. So how did the first Americans get there?
Alice discovers evidence for an ancient corridor through the Canadian ice sheet that may have allowed those first people through. But there are problems - in particular some very ancient finds in southern Chile seem to suggest a very different way in to the Americas. Amazingly, an ancient human skull discovered in Brazil even points to an Australasian origin of the Americans. Could a route from Australia across the Pacific have been possible? A surprising answer to the problem eventually comes from a Canadian forensic scientist, more used to solving murder cases.