Travel back through history, over 27,000 years into the past, when Arctic glaciers reached as far south as London and people faced a daily struggle not just to survive as individuals, families or groups, but to avoid the ultimate extinction of the species. A key moment in the course of history saw the two branches of humankind, the Neanderthals and the Cro-Magnons, face off against the backdrop of perilous cold, harsh conditions, and massive predators.