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takyon writes:

Scientists have found evidence of microbial life in a fossil dated to 3.7 billion years ago:

Rapid emergence of life shown by discovery of 3,700-million-year-old microbial structures (DOI: 10.1038/nature19355) (DX)

Biological activity is a major factor in Earth's chemical cycles, including facilitating CO₂ sequestration and providing climate feedbacks. Thus a key question in Earth's evolution is when did life arise and impact hydrosphere–atmosphere–lithosphere chemical cycles? Until now, evidence for the oldest life on Earth focused on debated stable isotopic signatures of 3,800–3,700 million year (Myr)-old metamorphosed sedimentary rocks and minerals from the Isua supracrustal belt (ISB), southwest Greenland. Here we report evidence for ancient life from a newly exposed outcrop of 3,700-Myr-old metacarbonate rocks in the ISB that contain 1–4-cm-high stromatolites—macroscopically layered structures produced by microbial communities. [...] The ISB stromatolites predate by 220 Myr the previous most convincing and generally accepted multidisciplinary evidence for oldest life remains in the 3,480-Myr-old Dresser Formation of the Pilbara Craton, Australia.

Reported at BBC, Ars Technica, and Reuters.

Original Submission