Humanity's written history stretches back only 5,000 years, a mere blip on the timeline of our existence. If you want to know what it really means to be fully human, to see the whole story, you need to go back. Way, way back. Prehistoric humans couldn't write, but they were adept at telling their own stories. On every continent and outpost where they gained a foothold, they left signs for modern man to decipher.  From the Middle Bronze Age settlement of Arkaim on the Kazakh Steppes to the temples of the Olmec in Mexico; from one of the first European proto-cities at Nebelivka in Ukraine to the neolithic henges of Avebury and Stonehenge; from the dolmens of Antequera in the heart of Andalucía to the megalithic culture that thrived in isolation on Indonesia's tiny Nias Island.