3.8billion-yr-old microbes raise hopes of finding life on Mars

Risingbd Desk: 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 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.

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.

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.

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.'

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.'

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.

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.

Source: The Mail



Risingbd/March 2, 2017/Mukul