Scientists claim to have discovered the oldest evidence of life on Earth: Canadian Arctic fossils that date back up to 4.28 billion years.
Claims about ancient life are often controversial and this one’s no exception – but, as the BBC notes, the researchers are confident in their findings.
The groundbreaking discovery could have a profound influence on our understanding of early life on Earth, and our search for it elsewhere.
The UCL researchers who led the international study said the remains of the microorganisms are, at the very least, 3.77 billion years old.
The oldest known microfossils before this discovery were found in Australia and dated back 3.46 billion years.
The putative Canadian fossils were encased in quartz layers in the Nuvvuagittuq Supracrustal Belt, which contains some of the oldest sedimentary rocks on Earth. It’s believed to have formed in a hydrothermal vent.
“Our discovery supports the idea that life emerged from hot, seafloor vents shortly after planet Earth formed. This speedy appearance of life on Earth fits with other evidence of recently discovered 3,700 million year old sedimentary mounds that were shaped by microorganisms,” said PhD student and first author Matthew Dodd.
UCL’s Dominic Papineau, who discovered the fossils, said the setting was “very probably” the cradle for lifeform between 3.77 and 4.28 billion years ago.
Speaking to the BBC about his eureka moment, he said: “I thought to myself ‘we’ve got it, we’ve got the oldest fossils on the planet’.
“It relates to our origins. For intelligent life to evolve to a level of consciousness, to a point where it traces back its history to understand its own origin - that’s inspirational.”
Not everyone’s convinced by the study. Professor Nicola McLoughlin from Rhodes University told the BBC she commended the scholarship, but said:
“The morphology of these argued iron-oxidising filaments from Northern Canada is not convincing.”
But the authors believe they can address any doubts.
Dr Papineau said in a statement announcing the findings: “The fact we unearthed the [fossils] from one of the oldest known rock formations, suggests we’ve found direct evidence of one of Earth’s oldest life forms.
“This discovery helps us piece together the history of our planet and the remarkable life on it, and will help to identify traces of life elsewhere in the universe.”
The researchers said the discovery demonstrates that life developed on Earth at a time when the surfaces of both Earth and Mars boasted liquid water.
That’s important because it suggests that NASA, which co-funded the project, may have been looking for life on Mars in the wrong places.
And if life did form just hundreds of millions of years after Earth, which is 4.6 billion years old, that could shape the debate about whether life on Earth is unique.
Dod added: “We expect to find evidence for past life on Mars 4,000 million years ago, or if not, Earth may have been a special exception.”