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How did life survive Earth’s great oxygenation?
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Woodward W Fischer , James Hemp and
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Joan Selverstone Valentine
Life on Earth originated and evolved in anoxic environments. capable of oxygenic photosynthesis. These organisms like-
Around 2.4 billion-years-ago, ancestors of Cyanobacteria ly supported themselves largely by means of anoxygenic
invented oxygenic photosynthesis, producing substantial photosynthesis at first, perhaps with only intermittent
amounts of O2 as a byproduct of phototrophic water oxidation. production of O2 in relatively small amounts. At this stage
The sudden appearance of O2 would have led to significant in Earth history, life did not have the defenses necessary to