Are these ‘microfossils’ the oldest evidence of life on Earth, at 3.77 billion years old?

Tiny, tubular structures uncovered in ancient Canadian rocks could be remnants of some of the earliest life on Earth, scientists say.

The straw-shaped “microfossils,” narrower than the width of a human hair and invisible to the naked eye, are believed to come from ancient microbes, according to a new study in the journal Nature. Scientists debate the age of the specimens, but the authors’ youngest estimate – 3.77 billion years – would make these fossils the oldest ever found.

Claims of ancient fossils are always contentious. Rocks as old as the ones in the new study rarely survive the weathering, erosion, subduction and deformation of our geologically active Earth. Any signs of life in the rocks that do survive are difficult to distinguish, let alone prove. Other researchers in the field expressed scepticism about whether the structures were really fossils, and whether the rocks that contain them are as old as the study authors say.

But the scientists behind the new finding believe their analysis should hold up to scrutiny. In addition to structures that look like fossil microbes, the rocks contain a cocktail of chemical compounds they say is almost certainly the result of biological processes.

If their results are confirmed, they will boost a belief that organisms arose very early in the history of Earth – and may find it just as easy to evolve on worlds beyond our own.