There’s a new paper in Nature that has everyone excited, for it reports what is said to be the earliest evidence for microbial life—”microbial structures” dated 3.7 billion years ago. The paper, by Allen P. Nutman et al. (reference and free link at bottom), describes what are said to be ancient traces of stromatolites—layered colonies of cyanobacteria that trap sediments and are thus fossilized—from a part of southwest Greenland that harbors old rocks.
The earliest previous evidence for microbial life are microfossils dated at 3.4-3.5 billion years old, coming from the Strelley Pool formation of West Australia. (Wacey et al., Nature Geoscience 4:698-702). The Nutman et al. finding, if true, pushes back the known existence of cells by 200-300 million years, no small chunk of time. (There is some evidence, though not very convincing, for carbon of biological origin dating back 4.1 billion years.)
What is the new evidence for 3.7 billion-year-old life? It’s largely structures in dated…
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