LIFE ON THE EDGE: SURVIVING EARTH'S GREATEST EXTINCTIONS

Billions of years before dinosaurs, before forests, before animals. The Earth was unrecognizable. No oxygen in the atmosphere. Orange sky, heavy with metal. Oceans were cloudy glass of dissolved iron. No plants. No animals. No moss. Yet life existed. Bacteria thrived around hydrothermal chimneys. Feeding on iron, sulfur, manganese. Life was flourishing—but captive.