3.77 billion year old rocks may contain earliest known fossils

Tiny filaments and straw-shaped tubes discovered in Canadian rocks believed to be more than four billion years old could be fossils belonging to the planet’s earliest known living organisms, according to new research published online Wednesday in the scientific journal Nature.

According to BBC News, the authors of the study reported discovering what they believe to be microbes in sedimentary rocks believed to be seafloor-hydrothermal vent-related precipitates in the Nuvvuagittuq belt in Quebec. The fossils, which are said to be one-tenth the width of a hair, were found to contain significant quantities of iron oxide in the form of hematite.


These iron filaments look surprisingly like microbial life. (Credit: M. Dodd)

While such claims about newly-discovered ancient fossils are always contentious in nature, lead author Matthew Dodd, a biochemist at University College London, and his colleagues insist that their discovery can be verified and that it could shed new light on the origins of life on Earth.

“The process to kick-start life may not need a significant length of time or special chemistry, but could actually be a relatively simple process to get started,” Dodd said to the Washington Post on Wednesday. “It has big implications for whether life is abundant or not in the universe.”

“This discovery answers the biggest questions mankind has asked itself – which are: where do we come from and why we are here?” he went on to tell BBC News. “It is very humbling to have the oldest known lifeforms in your hands and being able to look at them and analyze them.”

Findings could also impact the hunt for life on Mars

Dodd’s team discovered these purported microbes in rocks believed to be up to 4.28 billion years old, which would have been several hundred million years earlier than the time during which the first currently accepted evidence of ancient life on Earth would have existed, the BBC said.

In addition to the fossil organisms, the rocks were found to contain chemical compounds which the researchers believe was almost certainly left behind by biological processes, the Post noted. Those compounds, which include “isotopically light carbon,” are “associated with carbonate in direct contact with the putative microfossils,” the study authors wrote.

“Collectively,” they added, the observations they made in quartz layers from the Nuvvuagittuq Supracrustal Belt (NSB) “are consistent with an oxidized biomass and provide evidence for biological activity in submarine-hydrothermal environments more than 3,770 million years ago.” In short, they believe that the hydrothermal vents in which these rocks once rested were home to microbial organisms that lived between 3.77 and 4.28 billion years ago.

When these microbes died, the Post explained, iron in the water began to interact with their dead bodies, causing them to turn to stone as they decayed. These new rocks then went on to be buried and heated, then ultimately forced upward to form part of North America. If it can be proven that the structures detected were produced by biological processes, it could have an impact not just on our understanding of life on Earth, but on other planets as well.

“These organisms come from a time when we believe Mars had liquid water on its surface and a similar atmosphere to Earth at that time… So, if we have lifeforms originating and evolving on Earth at this time then we may very well have had life beginning on Mars,” Dodd said to BBC News. If that is the case, he and his colleagues believe that the best chance to find life on the Red Planet might be to analyze rocks believed to have been created by hydrothermal vents.


Image credit: Matthew Dodd