HOMO SAPIENS are decisively altering the conditions of earthly life, but we are not the first to do so. Some 2.4 billion years ago, cyanobacteria began to radically shift Earth’s biogeochemical trajectory. Through photosynthesis, these minute aquatic organisms kickstarted the Great Oxygenation Event, releasing oxygen into the atmosphere. Without cyanobacteria, evolution, and our species as we know it, would never have been feasible.
But unlike us, these single-celled geoengineers weren’t troubled by
