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3.6-billion-year-old fossils found in Greenland could be Earth's oldest

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Stromatolites made by very ancient microbes

Stromatolites in Shark Bay, Australia
Robert Young/Flickr

Australian geologists discovered some really weird and extremely old structures in Greenland: fossilized mounds made by microbes that are dated to about 3.6 billion years ago. That means life on Earth started early — shortly after our planet was formed, 4.5 billion years ago.

The structures — called stromatolites — were discovered in 2012, in a remote area of Greenland called Isua. The researchers noticed the weird formations that were once covered by snow and immediately understood they represented something unique. The discovery is described in a study published today in Nature.

Rocks from Greenland that show signs of ancient stromatolites.

The group followed the discovery by analyzing the formations in the lab. These analyses showed that the 2-inch high conical structures in the rocks had microbial origin. That’s also how the scientists ascertained the date for formation.

If the findings are confirmed, that would mean that the newly discovered fossils are older than the stromatolites previously found in Western Australia and dated to 3.4 billion years ago, according to Science. Until now, those fossils were considered Earth’s oldest. The Greenland fossils also suggest that life on Earth began very soon after our planet was formed, and when it was still very hot and bombarded by asteroids. And that has implications for life beyond our planet and Solar System.

If life began so early on Earth, maybe it means it’s more common than not in the Universe — starting with out closest neighbor, Mars.

"Three thousand seven hundred million years ago, Mars was wet," Allen Nutman, a geologist at University of Wollongong and co-author of the study told The Washington Post. "If life had managed to evolve to produce structures like stromatolites by 3,700 million years ago on Earth, there is an increased probability — certainly not a certainty — that the same type of process might have happened on Mars before it dried out."

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