S1, E5: When Homo sapiens turned up in prehistoric Europe, they ran into the Neanderthals. The two types of human were similar enough – intellectually and culturally - to interbreed. But as more Homo sapiens moved into Europe and the population increased, there was an explosion of art and symbolic thought which overwhelmed the Neanderthals. Ever since, we've had Europe - and the rest of the world - to ourselves.