The fossil, which was found in Quebec, Canada, shows life on earth was thriving as far back as 4.2 billion years, hundreds of millions of years earlier than previously thought, Joinfo.com reports with reference to Metro.
This makes the prospect of life on the Red Planet a distinct possibility, as it was also bombarded with comets that are thought to have brought the building blocks of life to earth.
The bugs are believed to have thrived in a deep sea hydrothermal vent system – volcanic activity on the ocean floor.
Scientists, from University College London, believe the minieral-rich environment in the hot water surrounding the vent may have provided habitats for the early life form.
Matthew Dodd, a member of the UK team, said: ‘Our discovery supports the idea that life emerged from hot, sea floor vents shortly after planet Earth formed.
‘This speedy appearance of life on Earth fits with other evidence of recently discovered 3,700 million year old sedimentary mounds that were shaped by micro-organisms.’
Previously the oldest reported microfossils, from Western Australia, were dated at 3.460 million years old.
However, some experts believe they may be non-biological features in the rocks.
Lead scientist Dr Dominic Papineau, from UCL’s Earth Sciences department, said: ‘The fact we unearthed them from one of the oldest known rock formations suggests we’ve found direct evidence of one of Earth’s oldest life forms.’
The scientists believe the find, that was co-funded by Nasa, could help the search for life on other planets including Mars.
The bugs were living on Earth at a time when Mars is thought to have had oceans or lakes of liquid water on its surface.
Mr Dodd, a PhD student, told the Telegraph: ‘Early Mars and early Earth are very similar places, so we may expect to find life on both planets at this time.
‘We know that life managed to get a foothold and evolve rapidly on Earth. So if we have life evolving in hydrothermal vent systems maybe even 4.2 billion years ago when both planets had liquid water on their surface, then we would expect both planets to develop early life.
‘If we do future sample returns from Mars and look at similarly old rocks and we don’t find evidence of life then this certainly may point to the fact that Earth might have been a very special exception, and life may just have arisen on Earth.’