Scientists say they have found the world’s oldest fossils, thought to have formed between 3.77bn and 4.28bn years ago.
Comprised of tiny tubes and filaments made of an iron oxide known as haematite, the microfossils are believed to be the remains of bacteria that once thrived underwater around hydrothermal vents, relying on chemical reactions involving iron for their energy.
If correct, these fossils offer the oldest direct evidence for life on the planet. And that, the study’s authors say, offers insights into the origins of life on Earth.
“If these rocks do indeed turn out to be 4.28 [bn years old] then we are talking about the origins of life developing very soon after the oceans formed 4.4bn years ago,” said Matthew Dodd, the first author of the research from University College, London.
With iron-oxidising bacteria present even today, the findings, if correct, also highlight the success of such organisms. “They have been around for 3.8bn years at least,” said the lead author Dominic Papineau, also from UCL.
The team says the new discovery supports the idea that life emerged and diversified rapidly on Earth, complementing research reported last year that claimed to find evidence of microbe-produced structures, known as stromatolites, in Greenland rocks, which formed 3.7bn years ago.
Oldest fossils on Earth discovered in 3.7bn-year-old Greenland rocks
However, like the oldest microfossils previously reported – samples from western Australia dating to about 3.46bn years ago – the new discovery is set to be the subject of hot debate.
The discovery of the structures, the authors add, highlights intriguing avenues for research to discover whether life existed elsewhere in the solar system, including Jupiter’s moon, Europa, and Mars, which once boasted oceans. “If we look at similarly old rocks [from Mars] and we can’t find evidence of life, then this certainly may point to the fact that Earth may be a very special exception and life might just have arisen on Earth,” said Dodd.
Published in the journal Nature by an international team of researchers, the new study focuses on rocks of the Nuvvuagittuq supracrustal belt in Quebec, Canada.