Oldest fossils found in Greenland, from
time Earth was like Mars
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[September 01, 2016]
By Alister Doyle
OSLO (Reuters) - The earliest fossil
evidence of life on Earth has been found in rocks 3.7 billion years old
in Greenland, raising chances of life on Mars aeons ago when both
planets were similarly desolate, scientists said on Wednesday.
The experts found tiny humps, between one and 4 cm (0.4 and 1.6 inches)
tall, in rocks at Isua in south-west Greenland that they said were
fossilized groups of microbes similar to ones now found in seas from
Bermuda to Australia.
If confirmed as fossilized communities of bacteria known as
stromatolites - rather than a freak natural formation - the lumps would
pre-date 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."
Earth formed about 4.6 billion years ago and the relative sophistication
of stromatolites indicated that life had evolved quickly after a
bombardment by asteroids ended about 4 billion years ago.
"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.
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Allen Nutman (L) 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, Australia,
August 23, 2016. Picture taken August 23, 2016. Yuri
Amelin/Australian National University/Handout via REUTERS
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 spin-offs, 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.
(Editing by Jeremy Gaunt)
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