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| Allen Nutman of the University of Woollongong and Vickie Bennet of the Australian National University hold a specimen of 3.7 billion-year-old fossils found in Greenland in Canberra Aug. 23. | YURI AMELIN/AUSTRALIAN NATIONAL UNIVERSITY / HANDOUT VIA REUTERS |
The experts found tiny humps, between 1 and 4 cm (0.4 and 1.6 inches) tall, in rocks at Isua in southwest Greenland that they said were fossilised groups of microbes similar to ones now found in seas from Bermuda to Australia.
If confirmed as fossilised communities of bacteria known as stromatolites — rather than a freak natural formation — the lumps would predate fossils found in Australia as the earliest evidence of life on Earth by 220 million years.
“This indicates the Earth was no longer some sort of hell 3.7 billion years ago,” lead author Allen Nutman, of the University of Wollongong, told Reuters of the findings that were published in the journal Nature.
“It was a place where life could flourish.”
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| This photo provided by Allen Nutman shows a rock with stromatolites, tiny layered structures from 3.7 billion years ago that are remnants from a community of microbes that used to be live. Scientists have found what they think is the oldest fossil on Earth, a remnant of life from 3.7 billion years ago when Earth's skies were orange and its oceans green. In a newly melted part of Greenland, Australian scientists found the leftover structure from a community of microbes that lived on an ancient seafloor, according to a study Wednesday in the journal Nature. | ALLEN NUTMAN / UNIVERSITY OF WOLLONGONG VIA AP |
“Stromatolites contain billions of bacteria … they’re making the equivalent of apartment complexes,” said Martin Van Kranendonk, a co-author at the University of New South Wales who identified the previously oldest fossils, dating from 3.48 billion years ago.
At the time stromatolites started growing in gooey masses on a forgotten seabed, the Earth was probably similar to Mars with liquid water at the surface, orbiting a sun that was 30 percent dimmer than today, the scientists said.
Those parallels could be a new spur to study whether Mars once had life, the authors said.
“Suddenly, Mars may look even more promising than before as a potential abode for past life,” Abigail Allwood, of the California Institute of Technology, wrote in a commentary in Nature.
The Greenland find was made after a retreat of snow and ice exposed long-hidden rocks. Greenland’s government hopes that a thaw linked to global warming will have positive spinoffs, such as exposing more minerals.
Nutman said the main controversy was likely to be that the fossils were in metamorphic rocks, reckoned to have formed under huge stress with temperatures up to 550 degrees Celsius (1,022°F) — usually too high to preserve any trace of life.
Still, Van Kranendonk told Reuters that dried-out biological material could sometimes survive such a baking, adding he was “absolutely convinced” by the Greenland fossils.
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