The oldest life on Earth has just been discovered in northern Canada.

About 35km north of Inukjuak, an Inuit village in northern Quebec, there’s an unusual rock outcropping. Known as the Nuvvuagittuq Supracrustal Belt, it’s made up mostly of grey-green rock, streaked with red veins. If you were to climb it, and you weren’t a geologist, you probably wouldn’t even notice what you were standing on. The rocks are thought to have formed billions of years ago at the bottom of prehistoric oceans, near ancient hydrothermal vents. And they bear the signature of an unusual ancient life form that could rewrite the history of planet Earth!

An international team of researchers say the rocks are between 3.8 and 4.3 billion years old - the oldest ever found on our planet. But that's not all. Their unusual structures are signs of the presence of ancient microorganisms, turning them into"microfossils"the oldest ever discovered, and also the oldest record of life on Earth.

Nuvvuagittuq Suprcrustal Belt, behind which is a small part of Nastapoka Island.

Our planet is only about 4.5 billion years old. When these rocks formed, the Earth had only been cooling and the oceans had formed a few hundred million years ago, the atmosphere was toxic, and the planet was in a state that would have been inhospitable to any form of life we ​​know today. This early period of Earth—called the Hadean Eon, which spanned between 4.5 and 4 billion years ago—was so hellish that it was named after Hades.

That's one of the reasons why discoveries like this are so important: if life could arise on early Earth, it could arise on other planets too!

Heematite pipes from NSB deposits at hydrothermal vents represent the oldest microfossils on the planet and also evidence for life on Earth.

Geochemist Dominic Papineau, from Quebec, made a field trip to the northern part of the province in 2011. To get there, he had to take three consecutive flights in small propeller planes, and a three-hour boat ride.

Papineau didn't expect to find fossils, largely because the rocks there were heavily metamorphosed (meaning they had undergone changes under immense pressure and heat beneath the Earth's crust—a process thought to destroy any signs of life).

Bright red refractive concretions of hematite siliceous rock containing microorganisms. A dark green volcanic rock at upper right shows hydrothermal deposits on the seafloor.

It was strange to see this bright red metal battlement scattered across the gray-blue landscape, Papineau said."One hypothesis about these rocks is that there was a biological influence in their formation"- said the professor of University of London (UCL).

Certain types of bacteria that exist today may be able to"harvest"nutrients from iron through a chemical reaction. Papineau wondered if similar organisms existed some 4 billion years ago?

"I was intrigued by the appearance of these rocks, so I sampled them"- Papineau said -“But what made me think something important might be stored inside them was when I found jasper concretions (mineral deposits formed by bacteria) at the site.”

Deposits of red iron (hematite - an iron mineral) found in jasper have resulted in the formation of numerous tubular, fibrous, granular, and rosette-shaped structures. While this suggests the possibility of biological origin, it is still only"capable"There are many ways that such structures can be created through non-biological interactions, so Papineau and other scientists will have to investigate further. One interesting feature of the formations is the layers of other minerals that surround them.

"The rosettes we obtained are made up of carbonate along with apatite and graphitic carbon. Carbonate and apatite are what make up bone."- he said.

Microscopic rosette composed of iron-carbonate with concentric quartz layers and a core of a single quartz crystal with a small amount of red hematite from the Nuvvuagittuq Supracrustal Belt.

In other words, these are highly organic materials that are likely to have originated from microfossils.

At UCL, Papineau and lead author Matthew Dodd used microscopy and spectroscopy to further study these organisms. Ultimately, they concluded that there was microfossil evidence of ancient iron-oxidizing organisms.

There are only a handful of places in the world where you can find rocks of this age. One of them is the sedimentary rocks in Greenland. In 2016, scientists announced that they had discovered fossils there that were 3.7 billion years old, and at the time, they were the oldest fossils ever found.

These fossils were formed during the same geological period as the rocks in this article, and were made by oxygen-breathing microorganisms. This means that not only was there life in the very early stages of our planet, but it was also quite diverse.

"If there were indeed oxygen-producing bacteria, and iron-oxidizing bacteria near hydrothermal vents, then life would have been quite diverse, since these bacteria are related (albeit distantly) to present-day microorganisms."- Papineau said.

A stacked stone marker made by the Inuit people.

The discovery of two distinct branches of life so early in the planet’s history opens the door to the search for life on other planets. If two separate species of bacteria could inhabit Earth so early, might they also be found near hydrothermal vents in ancient Martian seas, or even within Europa’s subsurface ocean? Scientists have found hematite concretions on Mars, in the form of"blueberries"discovered by the Opportunity rover.

Papineau chose Quebec as his target because, after learning about the research in Greenland, he knew similar specimens might be found closer to home."This is my home province. This is my country"- he said. By discovering ancient rocks in the north of this locality, he and his colleagues have rewritten the history of life on Earth.

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