Fossils point to oldest life on Earth
WASHINGTON — The best evidence yet for the oldest life on Earth is found in odd-shaped, rock-like mounds in Australia that are actually fossils created by microbes 3.4 billion years ago, researchers report.
“It’s an ancestor of life. If you think that all life arose on this one planet, perhaps this is where it started,” said Abigail Allwood, a researcher at the Australian Centre for Astrobiology and lead author of the new study. It appears Thursday in the journal Nature.
The strange geologic structures – which range from smaller than a fingernail to taller than a man – are exactly the type of early life astrobiologists are looking for on Mars and elsewhere.
They are known as stromatolites. They’re produced layer by layer when dirt sediments mix with carbon dioxide expelled from bacteria, water, and minerals – all trapped in the microbes’ sticky mucilage.
The theory is that these ancient mounds dotting a large swath of western Australia are not merely dirt piles that formed randomly into odd shapes, but that microbes built them a few billion years ago.
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