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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.
"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)
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