Oldest evidence of life on land found in 3.48 billion-year-old Australian rocks

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KATHY CAMPBELL / UNSW - Tara Djokic and Professor Martin Van Kranendonk found the fossils in the Dresser Formation in the Pilbara in Western Australia.

Fossils discovered by UNSW scientists in ancient hot spring deposits in the Pilbara have pushed back by 580 million years the earliest known evidence for microbial life on land.

Previously, the world’s oldest evidence for microbial life on land came from 2.7- 2.9 billion-year-old deposits in South Africa containing organic matter-rich ancient soils.

“Our exciting findings don’t just extend back the record of life living in hot springs by 3 billion years, they indicate that life was inhabiting the land much earlier than previously thought, by up to about 580 million years,” says study first author, UNSW PhD candidate, Tara Djokic.

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UNSW PhD student Tara Djokic in the Dresser Formation in the Pilbara Craton of Western Australia. Photo: Dale Anderson

“This may have implications for an origin of life in freshwater hot springs on land, rather than the more widely discussed idea that life developed in the ocean and adapted to land later.”

Scientists are considering two hypotheses regarding the origin of life. Either that it began in deep sea hydrothermal vents, or alternatively that it began on land in a version of Charles Darwin’s “warm little pond”.

“The discovery of potential biological signatures in these ancient hot springs in Western Australia provides a geological perspective that may lend weight to a land-based origin of life,” says Ms Djokic.

“Our research also has major implications for the search for life on Mars, because the red planet has ancient hot spring deposits of a similar age to the Dresser Formation in the Pilbara.

“Of the top three potential landing sites for the Mars 2020 rover, Columbia Hills is indicated as a hot spring environment. If life can be preserved in hot springs so far back in Earth’s history, then there is a good chance it could be preserved in Martian hot springs too.”

Source: University of New South Wales

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