Earth, water, wind, and fire…according to tradition, these four pieces make up the complex puzzle of our world. In the spirit of that tradition, is there a fifth component, one so close and disturbingly powerful that we choose to overlook it? This program reverses the concept that nature shapes human destiny and instead focuses on the impact our species has had, and will continue to have, on the Earth’s geological cycles. Perhaps surprisingly, the effects of human activity are not completely negative, even though today our footprint is bigger than ever and has the potential to do extreme, even irrevocable harm. The question viewers are left with is this—how will we use our influence over nature, now that we know its extent? A BBC/National Geographic-U.S. Co-production in Association with ZDF. Part of the series How Earth Made Us: The Untold Story of History. (50 minutes)