Life on Earth may have begun far earlier than thought, researchers have revealed.

Researchers claim to have discovered evidence of the earliest life ever found in 3.77 billion year old fossil microbes discovered on Canada's ancient sea floor .

If confirmed, the find is is at least 300 million years earlier than previous estimates - and the team who made the discovery say it suggests that there could also be life lurking on Mars.

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Experts from UCL studied tubes and filamentous structures preserved in the rocks that resemble similar structures attributed to bacterial life seen in other seafloor hydrothermal environments

THE OLDEST MICROFOSSILS There are no confirmed microfossils older than 3,500 million years on Earth. This is probably because of the highly metamorphosed nature of the oldest sedimentary rocks, according to the study. 'Therefore, studies have focused almost exclusively on chemical traces and primarily on the isotopic composition of carbonaceous material,' the researchers explained. Advertisement

The features are mineralized remains of what appear to be bacteria that lived some 3.77 billion to 4.28 billion years ago, the scientists said.

That would surpass the 3.7 billion years assigned to some other rock features found in Greenland, which were proposed to be fossils last August.

The new results come from examining rock found along the eastern shore of Hudson Bay in northern Quebec.

The microscopic filaments and tubes, composed of an iron oxide called hematite, appeared within a rock type called jasper.

A single strand may represent a chain of cells.

A team of experts led by Matthew Dodd of University College London (UCL) searched for signs of the earliest habitable environments on our planet.

Dodd said the microbes lived near a vent in the seafloor where water was heated by a volcano.

Since the fossil are nearly as old as Earth, which formed some 4.5 billion years ago, the finding supports previous indications that life may have begun in such an environment, he said.

Left: Layered haematite (red) and quartz (white) rock and right: a mass of haematite filaments, both from the 480 million-year-old hydrothermal vent deposit in Norway

Ironcarbonate rosette and a core of a crystal with inclusions of red hematite from the Nuvvuagittuq. These may have formed through the oxidation of organic matter from microbes living around vents

WHY DOES THIS SUGGEST LIFE ON MARS? Mr Dodd added: '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. 'Therefore, we expect to find evidence for past life on Mars 4,000 million years ago, or if not, Earth may have been a special exception.' Advertisement

The team analysed jasper rocks, believed to be from ancient hydrothermal vents, found in the Nuvvuagittuq belt in northeastern Canada.

The Nuvvuagittuq belt represents a fragment of the Earth's early oceanic crust and is made of basaltic rocks preserving pillow lava structures 'consistent with a submarine setting,' according to the researchers of the study.

The experts studied tubes and filaments preserved in the rocks that resemble similar structures attributed to bacterial life seen in other seafloor hydrothermal environments.

'Modern hydrothermal vent deposits host communities of microorganisms, some of which are iron-oxidising bacteria that form distinctive tubes and filaments,' the researchers wrote.

The new results come from examining rock found along the eastern shore of Hudson Bay in northern Quebec.

'Epifluorescence imaging [microscopes that use fluorescence to generate an image] of modern vent samples has shown that cylindrical casts composed of iron oxyhydroxide are formed by bacterial cells and are undeniably biogenic.

'Hence, morphologically similar tubes and filaments in ancient jaspers may be taken as biosignatures that can survive elevated temperatures and pressures.'

A CONTROVERSIAL CLAIM Two experts who've previously reported similar findings said they're not convinced. 'I would say they are not fossils,' Martin J. Van Kranendonk of the University of New South Wales in Australia, who reported the Greenland findings last year, wrote in an email. The paper's evidence for a biological origin falls short, he said. Abigail Allwood, a NASA geologist, said the authors have produced 'one of the most detailed cases yet made' for evidence of life in rocks older than 3.5 billion years. But 'it's an extraordinary claim to make and you do need extraordinary evidence,' she said. While the rock features could be signs of past life, she said, 'I think the jury is still out a little bit.' Stronger evidence for ancient fossils comes from several findings in rocks at around 3.5 billion years old, she said. Advertisement

The researchers believe that their findings point to life on other planets.

Mr Dodd added: '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.

'Therefore, we expect to find evidence for past life on Mars 4,000 million years ago, or if not, Earth may have been a special exception.'

The landscape from the the Nuvvuagittuq Supracrustal Belt in Quebec, Canada, showing a few Nastapoka Islands in the distant background

Left: convoluted layers of light-grey quartz and dark-grey magnetite, both a bit thinner than a Canadian penny. Right: Laminated hematitic chert (jasper) from the Early Ordovician time period

They explained that additional features preserved in these rocks, such as iron oxide granules and carbonate rosettes, are indicative of biological activity.

'Collectively, these observations are consistent with an oxidized biomass and provide evidence for biological activity in submarine-hydrothermal environments more than 3,770 million years ago,' they wrote.

In fact, there's a chance the fossilised microorganisms could date as far back as 4,280 million years ago.

The Nunavik territory in Quebec, Canada, showing the nearly perfect crescent of the Nastapoka structure in the lower left

Rock containing tubular and filamentous microfossils. This co-called jasper is in contact with a dark green volcanic rock in the top right and represent hydrothermal vent precipitates on the seafloor

These findings complement a recent report in the same journal about stromatolites — geological structures made by microbial colonies — from 3,700-million-year-old rocks in Greenland.

Stromatolites formed in the sunlit surface waters of the sea, and signs of life from hydrothermal vents show that even at this early date life had colonised the sea from its surface to the depths.

But not everyone is convinced of the findings.

Roger Buick, a professor in Earth and Space Sciences at the University of Washington in Seattle, said of the finding: 'I'm rather dubious that this finding will stand up to further scientific scrutiny.

'Where's the organic carbon in the filaments (rather than adjacent to them), where's the internal (rather than external) carbon isotope data supporting biological carbon fixation, where's the evidence of cellularity, where's the evidence of behavior?

'This study seems to have been held to a lower burden of proof than other microfossil reports and fails to meet the standards that would be required for a younger microfossil claim to be accepted. Possible, but not probable, and certainly not persuasive or compelling.'

The study was published in the journal Nature.