That Time Oxygen Almost Killed Everything

The video explores the history of oxygen on Earth, starting 3 billion years ago during the Archaean eon. Initially, Earth had little oxygen, and life was anaerobic. The emergence of photosynthetic bacteria introduced oxygen, drastically altering the planet's chemistry and climate. This led to the Great Oxygenation Event, causing mass extinctions and triggering ice ages. Despite these challenges, life adapted, leading to more complex organisms and the formation of an ozone layer. The video concludes with a sponsor message from Squarespace.

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