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Photosynthesis May Have Begun a Billion Years Earlier Than Previously Thought

The process critical to all complex life on Earth dates to around 3.8 billion years ago, according to new studies, putting into question prior theories about our planet's earliest organisms.

Structure of photosystem I | Curtis Neveu, Wikimedia Commons
Banded-iron formations such as this at Karijini National Park, Western Australia, often date to the time of the Great Oxygenation Event 2.45 billion years ago. Iron oxides lock in oxygen, which results from photosynthesis. | Graeme Churchard, Wikimedia Commons