A team of Australian and British geologists say in an article in Nature Geoscience they have discovered fossilized, single-cell organisms that are 3-4 billion years old — which would make them the oldest known fossils on earth.
The fossils were found in sandstone at the base of a rock formation in Western Australia.
What was Mother Earth like then, back at the beginning?
Geologists who peer back in time say the sandstone where the fossils were found with the aid of a powerful microscope was a beach on one of the few islands that had started to appear above the ocean’s surface.
Conditions were very different then. The moon orbited much closer to earth, raising huge tides. The atmosphere was full of methane, since plants had not yet evolved to provide oxygen, and greenhouse warming from the methane had heated the oceans to the temperature of a hot bath.
It was in these conditions, the geologists believe, that organisms resembling today’s bacteria lived in the crevices between the pebbles on the beech.
If this is an accurate timeline for the beginning of life on earth, then those one-celled critters made their appearance soon after what scientists describe as the Late Heavy Bombardment, which was a rain of destruction in which waves of asteroids slammed into our barely new planet, heating the surface to molten rock and boiling the oceans into steam. The bombardment, which ended around 3.85 billion years ago, give or take an eon, would have sterilized the earth’s surface and killed any incipient life.
CRITICS QUESTION whether this or similar discoveries of features found in slices of rock are truly fossils of once-living organisms or are merely crystals that took the form of cells by happenstance. Scientists David Wacey and Martin Brasier say they have found chemicals in the cells that are found primarily in living things and have used even more sophisticated methods to prove their identification is correct.
We find their theories comforting. If life began 3.5 billion years ago, shortly after the earth began, and an inexorable process of evolution started which took us all the way from one-celled organisms too primitive to be called either plant or animal to the Waceys and Brasiers of today’s world, think what another billion years could do for the species.
On Mondays, I would rather dwell on that big picture than call Washington, D.C. up to mind and cry me a river.
— Emerson Lynn, jr.
