Professor Brian Cox examines how it was that in a universe made of stars, rocks and endless space, a conscious civilisation was born. His latest adventure takes him from a submerged space station in Star City on the outskirts of Moscow, to Ethiopia, high above in the Great Rift Valley, where he encounters the geladas, mankind's distant ancestors. Despite once being Africa's most successful primate, a species who at one time roamed across the entire continent, these days they are found in one just place in the remote Ethiopian Highlands. Cox investigates why these ancestors retreated, yet modern mankind has expanded across the planet.