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Traces in rock may be the oldest evidence of life on Earth ever

Traces in rock may be the oldest evidence of life on Earth ever

New Scientist

Image: Matthew Dodd

Are we closing in on life’s cradle? What is claimed to be the oldest evidence of life on Earth yet found backs the idea that the first microbes originated around hydrothermal vents on the seafloor – but the work is already proving controversial.

Explaining the origin of life is one of the biggest unclaimed prizes in biology, and one that many scientists – including Nobel prizewinners – are chasing. The only thing we know for certain is that life must have popped into existence sometime between Earth’s formation 4.5 billion years ago and the appearance of the first undisputed fossils, about 3.4 billion years ago.

Most origin-of-life researchers base their theories on biochemical principles. But to seek direct evidence of life’s emergence, they must visit some of Earth’s last remaining wildernesses, including parts of Greenland, northern Canada and Antarctica. By chance these are the only places where Earth’s oldest rocks – and potentially fossils – can still be found.

Matthew Dodd at University College London and his colleagues have just finished analysing rocks collected from a region called the Nuvvuagittuq belt, in northern Quebec, Canada. The rocks here, on the coast of Hudson Bay, are at least 3.75 billion years old, and some geologists argue they are about 4.29 billion years old, which would mean they are just slightly younger than the planet itself. Read more on…