The Bacteria That Killed 99% Of Earth

Added: 2026-05-21

[00:00:00]One tiny bacteria killed almost everything on Earth.

[00:00:03]3 billion years ago, Earth's atmosphere was a toxic mix of methane and carbon dioxide. Then, a tiny organism called cyanobacteria figured out photosynthesis. They began pumping out oxygen as a waste product, eventually saturating the oceans and bleeding into the atmosphere. This transformed the sky from a dull orange to the vibrant blue we see today. But, for the anaerobic life of that era, oxygen was a lethal poison, triggering the first mass extinction in Earth's history. It also reacted with methane to trigger a global ice age, turning Earth into a giant snowball. Despite the chaos, this event created the environment necessary for complex life and the air that sustains us right now. Hi everyone, Mark here. If you are fascinated by the engineering of the future, subscribe and follow for more science, natural, and cosmic content.