Hexbyte – Tech News – Ars Technica |
The struggle is real —
Are these 3.7 billion-year-old fossils or just messed-up bedrock?
Few things in science seem to be as controversial as claims to the oldest evidence of life on Earth. As researchers strive to push life’s origins back further into the history of the early Earth, the evidence they have is never completely unambiguous. (If you were over three billion years old, you wouldn’t look so great, either.) Other scientists inevitably question any new evidence, and arguments ensue.
Hexbyte – Tech News – Ars Technica | Microbes in Greenland?
Two years ago, a group working in the ancient rocks of Greenland stumbled on some tantalizing cone-shaped distortions of rock layers. Based on several lines of evidence, the researchers concluded that they had found stromatolites, which are layered mounds built by communities of microbes in shallow water. Modern stromatolites are mainly known from Australia’s Shark Bay, but they were much more common when microbes ruled the Earth so are therefore one of the most obvious relics of life in the rock record. The Greenland find would push the age of the oldest-known stromatolite from about 3.45 billion years to 3.7 billion years.
But other researchers wanted to see these Greenland rocks for themselves. And in a newly published study led by Abigail Allwood, she and her team explain why they aren’t buying it.
Their first observation is the simplest—there’s a problem with the shape of the purported stromatolites. The original team worked with the face of the rock outcrop, but the new group managed to saw out a block of rock for a three-dimensional view. What looked like a cone from the front turned out to be more ridge-shaped—like thinking you’ve spotted a square chocolate and finding it’s actually one end of a long candy bar (except not quite so joy-inducing). What’s more, Allwood’s group found some tha