A team of Australian researchers has found the oldest fossils in the world, dating 3.7 billion years ago, in Greenland. They discovered stromatolites, mounds of carbonate constructed by microbes, the physical evidence that confirms that life emerged when the Earth was still young.
As reported in the journal Nature, the stromatolite fossils were found in the Isua Greenstone Belt, predating the former oldest stromatolite fossils in Western Australia by 220 million years. The Isua stromatolites, which the team says are complex ecosystems, were laid down in shallow sea and were only exposed by the recent melting of a perennial snow patch in the area.
“The significance of stromatolites is that not only do they provide obvious evidence of ancient life that is visible to the naked eye, but that they are complex ecosystems,” says lead researcher Allen Nutman, a professor at the University of Wollongong’s (UOW). “This indicates that as long as 3.7 billion years ago, microbial life was already diverse. This diversity shows that life emerged within the first few hundred million years of Earth’s existence, which is in keeping with biologists’ calculations showing the great antiquity of life’s genetic code.”
According to co-lead investigator Vickie Bennett, an associate professor from The Australian National University, the findings can show the conditions and environments during Earth’s early years without the need of speculation. Now, experts can understand how chemical cycles and rock-water-microbe interacted on a young planet.
The findings can also have implications on studies about Mars. The findings may indicate that life could have also existed on Mars. According to Martin Van Kranendonk, a professor and the director of the Australian Centre for Astrobiology at University of New South Wales, Earth’s oldest fossils could point to similar life structures on the Red Planet, which had a damp environment 3.7 billion years ago.