Life · Era

First Life

4.0 Bya – 2.5 Bya

Single-celled life emerges; oxygen begins to accumulate.

Date source not yet attached to this catalogue record.

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Key events

About 3.5 billion years ago

Evidence of ancient microbial life

Stromatolites in Western Australia preserve evidence associated with ancient microbial communities. They show life already existed around this time; they do not identify the exact moment life began. Geological context is essential when interpreting this evidence.

3.4 billion years ago

Photosynthesis Evolves

Cyanobacteria begin producing oxygen.

2.4 billion years ago

Great Oxidation Event

Oxygen floods the atmosphere, transforming Earth.

Era Overview

Period4.0 Bya – 2.5 Bya

Events and overlapping lifetimes are paginated below.

ScaleLife

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Historical Guide

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