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Scientists say life on Earth 鈥榦lder than we thought鈥
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LIFE on Earth is even older than we thought, Australian scientists said yesterday as they unveiled fossils dating back a staggering 3.7 billion years.
The tiny structures — called stromatolites — were found along the edge of Greenland’s ice cap, and were 220 million years older than the previous record holders.
They prove that life emerged fairly shortly — in geological terms — after the Earth was formed some 4.5 billion years ago, said lead researcher Allen Nutman of the University of Wollongong. And, he added, they offer hope that very basic life might at one point have existed on Mars.
“This discovery represents a new benchmark for the oldest preserved evidence of life on Earth,” Professor Martin Julian Van Kranendonk, a geology expert at the University of New South Wales and one of the study’s co-authors, said in a statement. “The structures and geochemistry from the newly exposed outcrops in Greenland display all of the features used in younger rocks to argue for a biological origin. It points to a rapid emergence of life on Earth.”
The Isua stromatolites — exposed after the melting of a snow patch in the Isua Greenstone Belt — matched other biological evidence on the evolution of the genetic code that placed the origins of life in a similar period, Nutman said.
Stromatolites are formed when microorganisms, such as certain kinds of bacteria, trap bits of sediment together in layers. These layers build up over time to create solid rocks. The rocks themselves were never alive, but their existence shows the very simple single-cell organisms that made them were present on Earth hundreds of millions of years earlier than previously thought.
Vickie Bennett of the Australian National University, who also worked on the project, said the research provided a new perspective on Earth’s history and “turns the study of planetary habitability on its head.”
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