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Oldest traces of life hint at existence of microorganisms 3.8 billion years ago


Life on Earth may have existed at least 3.8 billion years ago, a new study by and international team of scientists suggests based on evidence unearthed in Quebec, Canada.

Researchers led by University College London scientists found direct evidence of one of the oldest life forms on Earth when they unearthed tiny filaments and tubes formed by bacteria were found encased in quartz layers in the Nuvvuagittuq Supracrustal Belt (NSB), Quebec, Canada. Scientists say that these bacteria could have lived on iron.

The discovery of fossils of microorganisms said to be 3,770 million years old takes back the emergence of life on Earth by at least 310 million years. A previous study had found evidence of existence of life through fossils dated 3,460 million years ago.

For the latest study researchers systematically looked at the ways the tubes and filaments, made of haematite – a form of iron oxide or ‘rust’ – could have been made through non-biological methods such as temperature and pressure changes in the rock during burial of the sediments, but they found none of the possibilities likely. Scientists say that this leaves only one avenue open – biological method.

The haematite structures that have been unearthed have the same characteristic branching of iron-oxidising bacteria that are found near other hydrothermal vents today. Scientists found these structures alongside graphite and minerals like apatite and carbonate, which are found in biological matter including bones and teeth and are frequently associated with fossils.

Another evidence that hints at presence of life is that these mineralised fossils are associated with spheroidal structures that usually contain fossils in younger rocks, suggesting that the haematite most likely formed when bacteria that oxidised iron for energy were fossilised in the rock.

The filaments and tubes that scientists unearthed in their latest study are composed of the minerals expected to form from putrefaction, and have been well documented throughout the geological record, from the beginning until today. Scientists say that the fact that they were found in one of the oldest known rock formations indicate that they are direct evidence of oldest life forms on Earth.