Oldest fossils point to life on Earth 4 billion years ago

Phillip Butler
March 3, 2017

Microfossils up to nearly 4.3 billion years old found in Canada of microbes are similar to the bacteria that thrive today around sea floor hydrothermal vents and may represent the oldest-known evidence of life on Earth, scientists said on Wednesday.

The Nuvvuagittuq Supracrustal Belt (perhaps the best-named geological formation out there) is a stretch of rock in the northern part of Quebec, Canada, on the Hudson Bay.

"We can say life managed to emerge on Earth very rapidly nearly soon after the oceans had condensed on the surface of the Earth 4.4 billion years ago", said study lead author Matthew Dodd, a biogeochemistry graduate student at the University College London.

"The structures are composed of the minerals expected to form from putrefaction, and have been well documented throughout the geological record, from the beginning until today", said the study lead, Dr. Dominic Papineau, with UCL Earth Sciences and the London Centre for Nanotechnology. But do these microfossils have a biological origin?

Haematite tubes from the hydrothermal vent deposits in Quebec, Canada that represent the oldest microfossils and evidence for life on Earth. (There are also fossilized samples from Greenland known as stromatolites that are 3.7 billion years old, but these are structural mounds thought to be created by microorganisms rather than evidence of the microorganism itself decaying.) The UCL-led team was therefore under significant pressure to provide evidence that the NSB fossils truly formed through biological processes.

"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", added study leader Dominic Papineau. That would make them more than 300 million years older than the most ancient signs of life on Earth-fossilized microbial mats called stromatolites that grew in shallow seas. Such filaments and tubes have also been seen in much younger "microfossils", named due to their microscopic size, found in Norwegian rocks.

In the statement, Papineau described these tiny fossils- they're less than a millimeter long- as "direct evidence of one of Earth's oldest life forms". However he doesn't think what the researchers found is evidence of early life.

Recently discovered "microfossils" in Canada are the oldest ever found on Earth and could show life on the planet more than four billion years ago, according to a new study in the journal Nature.


"There's a lot of hot water circulating through these rocks that are full of elements, full of minerals ... we think this is the ideal environment where life could have started on Earth".

The trouble is that it's hard for scientists to pin down signs of tiny life-forms that lived billions of years ago, when the Earth has gone through so many other changes since then.

"Given this new evidence from the NSB, ancient submarinehydrothermal vent systems should be viewed as potential sites for the origins of life on Earth, and thus primary targets in the search for extraterrestrial life".

The tiny fossils - half the width of a human hair and up to half-a-millimetre in length - take the form of blood-red tubes and filaments formed by ocean-dwelling bacteria that fed on iron.

The fossils containing twisting, branching patterns of haematite - a type of rust - that the team believes were formed by bacteria that live near hydrothermal vents like those still seen at the bottom of the ocean today. "I am frankly dubious", she told The New York Times. The rosettes are freckled with dots and shards of other chemicals linked to life, such as phosphorus, a key ingredient for biological activity.

Prior to this study, the oldest known microfossils were found in western Australia and dated at around 3.5 billion years ago.

Dodd continued to say that when the structures were developed, both Earth and Mars would have had liquid water on their surfaces.

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