The Paradox of Oxygen
Early Earth’s atmosphere was largely oxygen-free, creating a world very different from today’s. The emergence of oxygen-producing microbes—most notably cyanobacteria—marked a dramatic turning point, releasing oxygen as a byproduct of photosynthesis. This transformation, known as the Great Oxidation Event, significantly altered Earth’s environment and drove the evolution of new life forms that could utilize oxygen for energy. The paradox lies in how life first adapted to and then radically altered its own planetary conditions.