Oldest fossils previously reported were dated at 3.46 billion years old.
The first life on Earth appeared around 300 million years earlier than previously thought, a new study has claimed. The discovery is based on an analysis of a fist-sized rock from Quebec, Canada, estimated between 3.75 and 4.28 billion years old.
Previously, researchers had found tiny filaments, knobs and tubes in the rock, which appeared to have been made by bacteria. However, not all scientists agreed that these structures had a biological origin. Therefore, after further analysis, the team at University College London (UCL) discovered a much larger and more complex structure inside the rock - a stem with parallel branches on one side that is nearly a centimetre long, as well as hundreds of distorted spheres alongside the tubes and filaments.
Now, according to a study published in Science Advances, researchers at UCL believe that while some of the structures could have been created through chance chemical reactions, the tree-like stem with branches was most likely biological in origin, as no structure created via chemistry alone has been found like it.
Lead author Dr Dominic Papineau, an associate professor in geochemistry and astrobiology at UCL, in a statement, said, “Using many different lines of evidence, our study strongly suggests a number of different types of bacteria existed on Earth between 3.75 and 4.28 billion years ago.”
“This means life could have begun as little as 300 million years after Earth formed. In geological terms, this is quick - about one spin of the Sun around the galaxy,” he added.
In the study, the researchers also provided evidence of how the bacteria got their energy in different ways. They discovered mineralised chemical by-products in the rock that are consistent with ancient microbes living off iron, sulphur and possibly also carbon dioxide and light. They stated that these findings suggest that a variety of microbial life may have existed on primordial Earth, potentially as little as 300 million years after the planet formed.
Notably, before this revelation, the oldest fossils previously reported were found in Western Australia and were dated at 3.46 billion years old, although some researchers have contested their status as fossils.