A team of international scientists have discovered a fossil in Canada that may be up to 4.28 billion years old. This would make it the oldest record of life on Earth by at least 100 million years.
The findings were reported this week in the journal Nature.
The fossil was found in the Nuvvuagittuq Greenstone Belt, a chunk of ancient ocean floor in Northern Quebec. The researchers looked at sections of rock known as “banded iron formations,” that were likely part of a system of hydrothermal vents—fissures from which heated, mineral-rich water erupted.
The iron formations were made billions of years ago as organisms reacted with dissolved iron in the water. The organisms, which are about one-tenth the width of a human hair, appear as red or white layers in the rock, and resemble structures produced by microbes living around undersea thermal vents today.
“It’s impressive,” said Jonathan O’Neill, an assistant professor at the University of Ottawa’s Department of Earth and Environmental Sciences. “We now have evidence in rock that I can hold in my hand that we had life already established extremely early on the Earth.”
The discovery of this fossil helps support recent research that Earth was capable of life much earlier than previously thought.
Our solar system is believed to have formed about 4.6 billion years ago. Scientists had previously theorized that early Earth was a lava-spewing, inhospitable world, barraged by asteroids, that could not have supported water or life at the young age of several hundred million years old.
However: “Within the last 15, 20 years, we have more and more evidence that that’s not the case,” said O’Neill. “Very quickly after its formation, the Earth became closer to what it is
today.” Scientists now believe that within about 300 million years of formation, or about 4.3 billion years ago, water existed on Earth’s surface.
With that water, combined with thermal activity, came life, at first in the form of microorganisms. “There’s a lot of hot water circulating through these rocks that are full of elements, full of minerals . . . we think this is the ideal environment where life could have started on Earth. You have the perfect conditions for life to start,” said O’Neill.
The research team dated the fossil as between 3.8 and 4.3 billion years old. The oldest known-fossil prior to this discovery was 3.7 billion years old.
As with any such claim, there is skepticism from the scientific community. Some scientists doubt that the fossils are the remains of microbes; others note that age of the fossil is controversial. “These rocks have a long and complicated history,” said Nigel Kelly of the University of Colorado at Boulder, “and so deciphering an unambiguous age and origin of these features will always be complicated.”
However, the research team remains enthusiastic. “The discovery answers the biggest questions mankind has asked itself, which are: where do we come from and why are we here?” said Matthew Dodd, who analyzed the structures at University College London.
“It relates to our origins,” said Dominic Papineau of the University College London, who discovered the fossils. “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.”
This discovery may also relate to the origin of life on other planets. “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,” said Dodd. “So if we have lifeforms originating and evolving on Earth at this time then we may very well have had life beginning on Mars.”