The oldest fossils in the world or old rocks? Geologists focus their efforts on minerals 3.7 billion years old

Two years ago, scientists published compelling evidence of ancient microbial life on Earth. At 3.7 billion years ago, layers of deformed Greenland rocks could hide the world's oldest fossils.

But a new document has questioned this "incredible" discovery. It's more plausible than the Toblerone-esque the grounds are simply the result of years of compression and deformation, said the authors.

In 2006, researcher Abigail Allwood and her colleagues reported traces of "stromatolites" 3.5 billion years old – structures built from a shallow sea, covered with microbes and lacustrine – in rocks in Australia. She was very surprised to learn that similar biological signatures had been reported in Greenland in 2016 and decided to take a look at herself.

Allwood visited the site and, with his team, concluded that the authors of the 2016 paper were probably wrong. Greenland's motives simply do not fit with Australian fossils, she told NPR.

"These are large ridges that extend deep into the rock," said Joel Hurowitz, geochemist at Stony Brook University in New York and another author of the last article. "This form is difficult to explain as a biological structure and much easier to explain as a result of compaction and deformation of rocks under tectonic pressures."

"Preserving those in such deformed rocks seemed unbelievable," said Allwood, who works at NASA's Jet Propulsion Laboratory. "And in fact, that was it, it was not credible."

But the authors of the 2016 document strongly contest the latest findings. Allwood and his team have examined samples from another area of ​​the Greenland site, the authors said in a statement shared with Newsweek. "This is a classic scenario of" comparing apples and oranges, "resulting in the inevitable result that our observations and observations do not match," they wrote.

Allwood and his team reviewed the site during a one-day visit, added the authors of the 2016 article, but did not take the offer to review the original rock specimens examined in their study.

Photograph of putative stromatolithic structures in outcrop (arrows). While most of the structures are facing down (the rock has been turned over), a point up (red arrow) clearly indicates that the structures have not developed from the seabed. Glove for the scale. Abigail Allwood

"We should not be surprised that there is a debate," said biogeochemist Noah Planavsky of Yale University – who has not participated in any of these studies National Geographic. The Allwood team performed a 3D analysis of the rocks, but the original authors did not do it – which was a "real gap" in the paper, he added. Allwood told the publication that other reviews of the site would help solve the mystery.

"My point of view is that interesting scientific discoveries arouse and should always be controversial.The important thing is that the debate on this subject is always well informed," said Allen Nutman, l & # 39; one of the authors of the 2016 study. Newsweek in an email. "I'm waiting for the veracity of [these] Stromatolites will be played over many years – the usual frantic speed of scientific controversy. "

The 2016 study, Allwood and his colleagues wrote in the last Nature This paper is a "telling story" for scientists looking for signs of life far more distant. Understanding these rock formations, for example, is a crucial step in the search for past life on Mars.