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World's oldest fossils could help find life beyond Earth

Fossils of 4-billion-year-old bacteria found in Canada hint at the origins of life on Earth. They may also help scientists looking for life on Mars and beyond.

Haematite tubes from the NSB hydrothermal vent deposits that represent the oldest microfossils and evidence for life on Earth.

Matthew Dodd

Scientists have discovered microfossils believed to be older than any others found to date. So old, in fact, they come from a time when both Mars and Earth would have had liquid water on their surfaces.

When life was first getting started on our planet, the original "hot spot" for a bit of microbial chillin' may have been around hydrothermal vents at the bottom of the ocean. Evidence for one ancient, microscopic gathering place has been found in rocks from northeastern Canada that contain what are believed to be the oldest fossils ever found.

An international team led by University College London scientists found tiny filaments and tubes formed by ancient bacteria encased in quartz layers from Quebec's Nuvvuagittuq Supracrustal Belt (NSB), home to some of the oldest sedimentary rocks on Earth. The rocks are likely what remains of a pre-prehistoric deep-sea hydrothermal vent system that was rich in iron, providing sustenance for the world's first life forms between 3.7 and 4.3 billion years ago.

"These discoveries demonstrate life developed on Earth at a time when Mars and Earth had liquid water at their surfaces, posing exciting questions for extra-terrestrial life," said UCL Ph.D. student Matthew Dodd in a press release. Dodd is the lead author on a study detailing the findings in this week's issue of the journal Nature. "Therefore, we expect to find evidence for past life on Mars 4 billion years ago, or if not, Earth may have been a special exception."

Before this new discovery, the oldest known microfossils were from western Australia and dated back 3.46 billion years, although there was some question whether or not they were of truly biological origin.

The researchers behind the new discovery say they tried to eliminate possible non-biological means that could have formed the tubes and filaments. They say the structures they found are frequently associated with fossils formed by bacteria oxidizing iron for energy.

"The fact we unearthed them from one of the oldest known rock formations, suggests we've found direct evidence of one of Earth's oldest life forms," said lead researcher Dr. Dominic Papineau from UCL. "This discovery helps us piece together the history of our planet and the remarkable life on it, and will help to identify traces of life elsewhere in the universe."

NASA, Elon Musk and other space explorers and astrobiologists may want to take note, as the researchers believe their findings could be handy to anyone looking for evidence of past life on Mars or perhaps even organisms currently hanging out in similar hydrothermal vent systems on worlds like Europa.

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