New fossil evidence could rewrite the history of life on Earth. 300 million years earlier?

A team of scientists believes some of the oldest fossils found on Earth contain signs of the earliest life on our planet, a press statement reveals.

These samples predate traditional scientific estimations for the beginnings of life on Earth by hundreds of millions of years.

According to researchers, the ancient fossils are between 3.75 billion and 4.2 billion years old. If their belief that the samples are biological in origin is true, it would completely change our understanding of the evolution of life on Earth. It would ultimately rewrite the timeline for the origin of microbial life on Earth, meaning its emergence occurred up to 300 million years earlier than previously believed.

That would mean that relatively speaking, the earliest known organisms are only a little younger than the Earth itself. The discovery has potentially huge implications therefore for our understanding of the evolution of life on Earth, as well as for the search for extraterrestrial life.

In a paper in the journal Science Advances, the researchers from University College London, detail their analysis of fossil samples they found at a dig site in northern Québec, Canada. The fossil samples were originally collected in 2008 by UCL associate professor Dominic Papineau. After the initial finding, Papineau and colleagues argued in a 2017 paper in the journal Nature that the filaments and tubes preserved in the fossils were a sign of biological processes. This led to great debate within the scientific community, with detractors claiming the same filaments could have been produced by geological processes.

"A diverse microbial ecosystem on the primordial Earth"

Since the 2017 paper, Papineau and his colleagues have been working to provide further insight with a view to strengthening their argument. In their new paper, they provide their findings, which they claim might reveal "a diverse microbial ecosystem on the primordial Earth that may be common on other planetary bodies, including Mars."

The researchers not only claim to have further evidence for their own theory, but they also believe their new findings disprove claims that the shapes found in their fossil samples were created by geological processes. They employed new techniques and studied a larger sample that includes a stem-like structure they believe is hard to explain without the existence of living organisms at the time. According to the scientists, their more comprehensive investigation leads them to believe that iron-eating microbes — like the ones that live in hypothermal vent systems today — may have formed the patterns in their samples.

A long-held scientific theory suggests life first originated at these ocean vents, which provide the heat and materials required for microbial life to thrive. The new finding might lend weight to this theory, suggesting such vents on other planets could be one of the focal points for future missions aimed at discovering microbial life on other planets.