Europe - 500,000 years ago
Nearly half a million years ago, an advanced species of human roamed Europe.
Strong and powerful, Homo heidelbergensis were fierce hunters...
They used sophisticated tools and lived in close-knit family groups.
However, heidelbergensis were missing something vital.
They could only see the world as it was; they were lacking the thing that makes us human - imagination.
Over some 200,000 years, the heidelbergensis were split into two populations by extreme weather and environment, causing them to evolve into two very different species.
Homo heidelbergensis evolved into:
In the north were Homo neanderthalensis, their physical power and resilience key to surviving in the ice age of northern Europe.
140,000 years ago
They were shorter than the heidelbergensis reaching only about 1.5m, with short limbs and extremities to retain vital heat.
Neanderthals were also incredibly tough and could cope with immense pain that we would find unbearable.
In Africa - about 140,000 years ago and in the grip of a devastating drought - the other descendents of heidelbergensis, Homo sapiens, were close to extinction.
140,000 years ago
But this extreme environment drove the development of imagination.
Homo sapiens began to understand and anticipate future possibilities.
For example, they would store food and water for future use, because they could imagine the impacts of another dry season.
It was this forward thinking that would save them from extinction.
It was recently discovered that Homo sapiens and Homo neanderthalensis interbred, and that between 1% and 4% of DNA in modern man is from neanderthals.
But eventually it would be the small band of Homo sapiens in Africa who would come to dominate the world and evolve into modern man.
Over millions of years it was our ancestors' ability to adapt to the ever-changing world around them that eventually led to us.