Oldest fossils disputed:
Discovery
When Australian scientists presented evidence in 2016 of life on Earth 3.7 billon years ago — pushing the record back 220 million years — it was a big deal, influencing even the search for life on Mars.
But that discovery, based on an analysis of primordial rocks in Greenland, has now been challenged, with another team of researchers arguing in a study published Wednesday that the structures presented as proof of microbial activity were, in fact, geologically forged by underground heat and pressure.
The truth hinges on whether the cone-shaped formations in question are genuine stromatolites, layered structures left in the wake of water-dwelling microorganisms.
Previously, the earliest confirmed stromatolites were found in 3.45-billion year old rocks in Australia.
Being able to accurately date the first stirrings of life on our young planet — roughly a billion years old at the time — has important implications for understanding how it emerged and evolved.
Writing in the journal Nature, Abigail Allwood of the California Institute of Technology and colleagues analyzed the threedimensional shape of the disputed formations, along with their orientation in space and chemical composition. (Agencies)