3.7 billion-year-old fossils uncovered in Greenland are maybe the oldest signs of life

AP

Fossils found on the coast of Greenland may be the oldest signs of life ever discovered, dating back 3.7 billion years, the Washington Post reported.

The stromatolites, fossils formed from ancient biomaterials called microbial mats, were found in Isua, a remote part of Greenland known for it's absurdly old belt of rock formations. 

According to geologist Allen Nutman from the University of Wollongong in Australia, his team found outcroppings he hadn't seen in the three decades he's been studying the area — until the melt caused by climate change, and the low snowfall from the previous winter, made it visible. 

If the fossils are actually as old as recorded in Nutman's paper, published Wednesday in the journal Nature, that means they predate the last confirmed-oldest fossils by about 200 million years. According to the paper, the stromatolites found were fairly complex organisms, with the capacity to undergo photosynthesis. This suggests they descended from more primitive ancestors from over 4 billion years ago — edging life on Earth closer to the planet's birth about 4.54 billion years ago.

Left: an overturned limb of the Isua outcropping. Right: a detailed area of the stromatolites foundSource: Nature
Left: an overturned limb of the Isua outcropping. Right: a detailed area of the stromatolites found  Nature

But it's difficult for scientists to make definitive conclusions about the findings. Abigail Allwood, a geologist at NASA's Jet Propulsion Laboratory told the Post, the evidence of these stromatolites "are not as clear cut as you'd ideally want for such an extraordinary claim," adding that if we found these same results on Mars, for instance, we wouldn't necessarily say we'd found life.

"We expect there will be some robust debate. That's what science is all about," Nutman said.

Sure, skepticism is natural — especially if you're making a claim that puts life on Earth 200 million years earlier than the last proven timestamp. But, say scientists, skepticism is part of the game. 

"The history of geology is that the more we learn the older things become," Michael Russell, a research scientist at NASA JPL's Planetary Chemistry and Astrobiology Group who wasn't involved in the study, said in an interview. "But I have a hunch it's a very good piece of work. After all, they're well-versed in stromatolites in Australia. They saw the 3.5 million-year-old ones."

An area of Greenland near the Arctic CircleSource: Evan Vucci/AP
An area of Greenland near the Arctic Circle  Evan Vucci/AP

If life's new birthday isn't enough, Nutman says, the findings even have exciting implications for discovery off-world, too.

"It means that there is a heightened interest in the search for life on Mars," Nutman said, according to the Post. "Three thousand seven hundred million years ago, Mars was wet. 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."