Image: Mosiac of the Yellowknife Bay area of Gale Grater taken by the NASA Mars rover Curiosity. Scientists found strong evidence of an ancient lake and stream deposits suggesting past environmental conditions suitable for microbial life. Credit: NASA/JPL/Caltech/MSSS The discovery of fossilized microbial life that is 220 million years older than anything previously found on Earth sweetens the prospect that life may have developed on Mars as well, which was not all that different from Earth at the time.
"Earth's surface 3.7 billion years ago was a tumultuous place, bombarded by asteroids and still in its formative stages," Abigail Allwood, an astrobiologist at NASA's Jet Propulsion Laboratory in Pasadena, Calif., wrote in a commentary published in this week's Nature.
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"If life could find a foothold here, and leave such an imprint that vestiges exist even though only a minuscule sliver of metamorphic rock is all that remains from that time, then life is not a fussy, reluctant and unlikely thing. Give life half an opportunity and it'll run with it," Allwood wrote.
Allwood's essay accompanied research results , also published in Nature, from a team of Australian scientists who found evidence of life in Earth's oldest rocks, located in Greenland.
"These are not the kinds of rocks that palaeobiologists would consider a good prospect for signs of life, because they are not sedimentary like those that host most of Earth's fossil record. Rather, they are metamorphic, which means that they have been extensively deformed and altered by heat and pressure during deep burial," Allwood notes.
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Allen Nutman, a researcher at the University of Wollongong in Australia, and colleagues came across what Allwood describes as "a rarity" in Greenland's Isua Greenstone Belt.
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