Credit, Credit: Matthew Dodd
Iron-rich filaments from rocks in the province of Quebec, Canada, would indicate evidence of life on Earth
Scientists have discovered what they believe to be the fossils of some of Earth’s earliest living organisms.
They are tiny filaments, pieces and tubes in rocks located in Canada that are up to 4.28 billion years old.
If the age estimate of the microfossils is truly correct, the emergence of life would have occurred “shortly” after the formation of the planet, 4.54 billion years ago.
It would also represent a jump of hundreds of millions of years from the earliest known evidence.
The study was published in the scientific journal nature.
The findings are still controversial, but the team, made up of international scientists, say they believe they have no doubts about the discovery.
The alleged fossilized microbes are one-tenth the width of a human hair and contain significant amounts of hematite – a type of iron oxide or “rust”.
Matthew Dodd, who has analyzed structures at University College London (UCL), UK, argues the discovery sheds light on the origins of life.
“The discovery answers the questions that humanity asks, such as: where did we come from and why are we here?”, he says.
The fossil structures were coated with layers of quartz in the so-called Nuvvuagittuq Supracrustal Belt (NSB).
Credit, Dominique Papineau
The rock contains what experts have identified as microfossils
The NSB is a patch of ancient ocean floor that contains some of the oldest sedimentary and volcanic rocks known to science.
Controversial
The team observed segments of rock that likely formed in a system of hydrothermal vents – fissures in the seabed from which heated, mineral-rich water erupts.
These springs are known to be important habitats for microbes today.
According to Dominic Papineau, also from UCL, who discovered the fossils in the province of Quebec, this type of formation was also, most likely, the cradle of different forms of life between 3.77 billion and 4 years ago, 28 billion years.
Credit, GEORGETTE DOUWMA/SCIENTIFIC PHOTO LIBRARY
Hydrothermal activity on the ocean floor may have been a habitat for early life
He described how he felt when he realized the significance of the material he was working on.
“I said to myself: ‘I did it, I recovered the oldest fossils on the planet'”, he says.
“Discovery goes back to our origins. For intelligent life to evolve to a level of consciousness, to the point where you can go back in history to understand where you came from – it’s inspiring,” he added. .
Any claim of Earth’s oldest life is always shrouded in controversy.
Indeed, it is often difficult to prove that certain structures may not have been produced by non-biological processes.
In addition, the analysis of this material is complicated because the rocks normally undergo alterations.
NSB, for example, has been pressed and heated all this time.
Credit, WALTER MYERS/SCIENTIFIC PHOTO LIBRARY
Life on Earth originated billions of years ago
Currently, the oldest evidence of life on Earth comes from 3.48 billion year old rocks found in Western Australia.
The material contains remnants of stromatolites – accumulations of sediment formed from mineral grains stuck together by ancient bacteria.
Another discovery of stromatists was made in August last year. The team behind the discovery said the fossil evidence was 3.7 billion years old.
However, Papineau admits that the idea that microorganisms metabolize oxygen so soon after the Earth was formed will surprise geologists.
“They didn’t consider that there were oxygen-breathing organisms at that time. This brings oxygen production back to the Earth’s surface, albeit in small amounts, at the start of the record. sedimentary,” he said.
However, Nicola McLoughlin of Rhodes University in South Africa, who was not involved in the study, questioned the scientists’ conclusions.
“The morphology of these putative oxidized iron filaments from northern Canada is unconvincing,” she told the BBC.
“In recent deposits, we see spectacular twisted rods, usually arranged in layers, but in the highly metamorphosed rocks of the Nuvvuagittuq belt, these filaments have a much simpler shape,” he explains.
Credit, Dominique Papineau
Fossils were discovered by scientist Dominic Papineau
“The textural and geochemical evidence for graphite in carbonate rosettes and magnetite-hematite granules is painstaking work, but it only provides indications of microbial activity; it does not strengthen the case for the biogenicity of the filaments. .”
She also says that the maximum age of the rocks has already proven to be controversial and that the true age is probably closer to 3.77 billion years.
In part, knowledge of the earliest living organisms is important because it paves the way for the discovery of other types of life beyond the solar system.
“These organisms come from a time when we think Mars had liquid water on its surface and an atmosphere similar to Earth’s at that time,” Dodd said.
“So if we had life forms originating and evolving on Earth at that time, then we could have had life originating on Mars.”
Credit, Mr Dodd
Iron clusters and filaments show similarities to modern microbes
If so, Papineau says recent NASA space missions to the surface of Mars could be looking for signs of life in the wrong places.
According to him, the Mars Exploration Vehicles (MER), Spirit and Opportunity missions, and more recently the Curiosity spacecraft, have overlooked areas that may have had rock from hydrothermal vents.
“On the surface of Mars, we missed opportunities. The MER-B (Opportunity) in 2003 discovered promising formations, but there was no analysis. And Spirit passed another near the Comance region in the Gusev crater,” he said. .
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