WASHINGTON, Sept 27 (Reuters) - Rocky outcrops in eastern Canada contain what may be some of the oldest evidence of life on Earth, dating back about 3.95 billion years.
Scientists said on Wednesday they found indirect evidence of life in the form of bits of graphite contained in sedimentary rocks from northern Labrador that they believe are remnants of primordial marine microorganisms.
The researchers carried out a geological analysis of the Labrador rocks and measured concentrations and isotope compositions of the graphite, and concluded that it was produced by a living organism.
They did not find fossils of the microorganisms that may have left behind the graphite, a form of carbon, but said they may have been bacteria.
CANADA - JUNE 30: Trout River Lake, Gros Morne National Park (UNESCO World Heritage List, 1987), Newfoundland and Labrador, Canada. (Photo by DeAgostini/Getty Images)
CANADA - JUNE 30: The Tablelands, Gros Morne National Park (UNESCO World Heritage List, 1987), Newfoundland and Labrador, Canada. (Photo by DeAgostini/Getty Images)
CANADA - CIRCA 2000: The Schefferville train in Quebec, Canada in 2000 - Iron ore train coming from Labrador City - Its 167 freight cars form a convoy of nearly 2 kilometers - There are forty convoys each week - Loaded to the top with iron ore, they tear along toward Sept-Iles - Equipped with GPS, they are controlled meter by meter along the way by stations and by a flight of low-flying helicopters. (Photo by Jean-Erick PASQUIER/Gamma-Rapho via Getty Images)
CANADA - 1989/01/01: Canada, Newfoundland, No. Labrador, Saglek Fjord, Tundra In Fall Colors. (Photo by Wolfgang Kaehler/LightRocket via Getty Images)
Fishermen's drying huts in Pouch Cove, Newfoundland and Labrador, Canada, circa 1965. (Photo by Adrian Ace Williams/Archive Photos/Getty Images)
Fog along the rocky Atlantic Ocean shoreline of the Mistaken Point Ecological Reserve in the Avalon Peninsula of Newfoundland and Labrador.
Typical landscape in Labrador, granit rocks.
A view of the rugged coastline from Red Bay, Labrador. Saddle Island is in the background, with the rugged rocky and treed coast in the foreground.
The town of Red Bay, Labrador, hugging the shoreline with its colourful buildings and mountains int he background.
Labrador - natural rock statue in National reservoir in General Carrera lake, Marble caves.
Inukshuk at the Red Bay National Historic Site of Canada - Interpretation Centre, Red Bay, Labrador Coastal Drive, Viking Trail, Strait of Belle Isle, Southern Labrador, Newfoundland & Labrador, Canada.
Waterfall, Tucked Away Falls (un-named), in the Mealy Mountains, Southern Labrador, Newfoundland and Labrador, Canada.
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"The organisms inhabited an open ocean," said University of Tokyo geologist Tsuyoshi Komiya, who led the study published in the journal Science.
Earth formed about 4.5 billion years ago and the oceans appeared roughly 4.4 billion years ago. The new study and some other recent research indicate that microbial life emerged earlier than previously known and relatively soon after the Earth's formation.
Canada has produced some of the most ancient signs of life. Another team of scientists in March reported that microfossils between 3.77 billion and 4.28 billion years old found in northern Quebec, relatively close to the Labrador site, are similar to the bacteria that thrive today around sea floor hydrothermal vents.
Other scientists last year described 3.7 billion-year-old fossilized microbial mats, called stromatolites, from Greenland.
(Reporting by Will Dunham; Editing by Sandra Maler)