Microfossils of bacteria living 3.4 billion years ago were found in Australia. Earth had no oxygen at the time the bacteria existed. The finding from a remote region of Western Australia lends hope that life has existed on Mars. The sample came from the remote Pilbara region of Western Australia, a site called Strelley Pool, where the microbes, after dying, had been finely preserved between quartz sand grains. In 2002, another team of scientists, working in the same region just 35 kilometers (20 miles) away, said they had found bacteria fossils in the same formation.
But the claim was disputed, with some experts saying that the tiny pockmarks were not the signatures of once-living organisms but the result of mineralization of the rocks.
Drawing on the latest electron microscopy and spectroscopy techniques, the authors of the new study say they have triple proof that their sample is biological in origin.
The microbes fed on sulphur compounds to survive, they believe.
The marks measure only about 10 millionths of a meter (0.0004 inches) long.
"At last we have good solid evidence for life over 3.4 billion years ago. It confirms there were bacteria at this time, living without oxygen," Martin Brasier, a professor at Oxford University, said in a press release.
"Could these sorts of things exist on Mars? It's just about conceivable,' said Brasier.
Robots or astronauts sent to the Red Planet could look at Pilbara-like sites to find out. However, their samples would have to undergo similar scrutiny to support beliefs that life has existed on Earth's enigmatic neighbor.
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