The final episode examines the fate of the Neanderthals, our European cousins who died out as modern humans spread from Africa into Europe during the Ice Age. Did modern humans interbreed with Neanderthals or exterminate them? As for Homo sapiens, we have planet Earth to ourselves today, but that's a very recent and unusual situation. For millions of years, many kinds of hominids co-existed. The program looks at why 'we' survived while those other ancestral cousins died out