During the Stone Age, humans shifted from the nomadic lifestyle to the more settled life of farmers. Part 1 of this two-part documentary illuminates the background of these changes and shows the difficulties Stone Age humans had to contend with. Until around 10,000 BC, humans lived as hunters and gatherers. Then an irreversible change began. Settlements formed. "For millions of years humans lived as foragers and suddenly their lives changed radically. This was far more radical than the start of the digital age or industrialization," says prehistorian Hermann Parzinger, president of the Prussian Cultural Heritage Foundation. For a long time, scholars believed that a sedentary lifestyle was a prerequisite for constructing large buildings. Then archaeologist Klaus Schmidt discovered Göbekli Tepe in southern Turkey, a 12,000-year-old complex of stone blocks weighing up to 20 tons. Its builders were still hunter- gatherers. They decorated the stone columns with ornate animal reliefs. How these structures were used and who was allowed access to them remains a mystery.