Researchers have discovered hints of life hundreds of millions of years earlier than previously known, according to a new study published in Nature. An international team of scientists led by University College London’s Matthew Dodd have found the oldest microfossils ever in what was once a hydrothermal vent system near Quebec, estimating they could be up to 4.3 billion years old.

Located on the eastern edge of Canada's Hudson Bay, the Nuvvuagittuq Greenstone Belt is left over from Earth’s earliest oceanic crust. There, within the quartz layers of banded iron formations, the researchers found remains of tubes and filaments (seen attached to a clump of iron in the image below) formed by bacteria on that early crust, which was part of an ancient deep-sea hydrothermal vent network.

M. Dodd

 
The bacterial remnants can be dated back at least 3.77 billion years, older than previously discovered evidence of the beginnings of life on Earth. The oldest confirmed evidence of bacterial life before this, discovered in western Australia, was dated at around 3.5 billion years ago.

Other research has pointed to life 3.7 billion years ago, but scientists were uncertain if the microfossils in question were really biological in origin or formed by some other process. In this study, researchers tested several ways the tubes and filaments discovered could have been created, like through temperature and pressure changes, but found that the most likely origin of the structures was biological. The tubes and filaments studied look much like those formed by bacteria in modern hydrothermal vents, according to the researchers.

M. Dodd

 
The newly discovered remains push the timeline of life on Earth back even further. They are probably from even earlier than 3.8 billion years ago and may date to 4.3 billion years ago, according to the study. The planet itself is thought to be around 4.5 billion years old, and multicelled organisms didn’t show up until 600 million years ago. “The findings support the theory that life emerged from hot, sea floor vents shortly after the formation of Earth,” co-author and University of Ottawa professor Jonathan O’Neil explains in a press statement.