In the first episode, Roberts introduces the notion that genetic analysis suggests that all modern humans are descended from Africans. She visits the site of the Omo remains in Ethiopia, which are the earliest known anatomically modern humans, and visits the San people of Namibia to demonstrate the hunter-gatherer lifestyle. In South Africa, she visits Pinnacle Point, to see the cave in which very early humans lived. She then explains that genetics suggests that all non-Africans may descend from a single, small group of Africans who left the continent tens of thousands of years ago. She explores various theories as to the route they took. She describes the Jebel Qafzeh remains in Israel as a likely dead end of a traverse across Suez, and sees a route across the Red Sea and the around the Arabian coast as the likelier route for modern human ancestors, especially given the lower sea levels in the past.