A team of international scientists has found the oldest record of life on Earth in Northern Quebec, dating back at least 3.8 billion years.
Our solar system formed about 4.6 billion years ago. Scientists believe that about 4.3 billion years ago, water already existed on Earth's surface. However, what isn't known is when the earliest life emerged. Recent research has found life at 3.4 billion years and, most recently 3.7 billion years.
The discovery was made in the Nuvvuagittuq Greenstone Belt in Northern Quebec in rock known as "banded iron formations." These formations existed billions of years ago, a result of organisms reacting with dissolved iron in the water that covered the planet. They appear in rock as red or white layers.
While there is some debate as to whether or not the the age of the rock in the Nuvvuagittuq Greenstone Belt is 3.8 billion years old or 4.3 billion years old, Jonathan O'Neil, assistant professor at the University of Ottawa's Department of Earth and Environmental Sciences, believes it to be on the older side. But even if the rock is younger than that, it would still make their finding the oldest record of life on Earth, by 100 million years.
"It's impressive," O'Neil said. "We now have evidence in rock that I can hold in my hand that we had life already established extremely early on the Earth."
Discoveries such as this one greatly help scientists better understand the early Earth. O'Neil said that scientists had previously theorized that Earth was a truly inhospitable place at this young geological age, a searing, active world with molten lava lakes incapable of supporting any surface water or life. However, O'Neil said that recent research is painting a far different picture.
"Within the last 15, 20 years, we have more and more evidence that that's not the case," he said. "Very quickly after its formation, the Earth became closer to what it is today. We already have evidence of water at the surface of the Earth by about 4.3 billion years ago."
And it's in that water, together with thermal activity below where life began to flourish, first as microorganisms.
Below the surface water, the ocean crust would have been literally bubbling with activity: with hydrothermal vents, the water heated by volcanic activity.
"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."
Today, that process continues in deep parts of our oceans.
Tubes of life
The rocks found in Quebec, reveal tiny, tubular structures of hematite. Hematite, a type of iron oxide, is one of the most common minerals on Earth.
These structures could also have been created by temperature and pressure rather than organisms. However, upon closer examination, the research team discovered the structures were similar to those found at thermal vents today. As well, they were found together with other minerals that are found in biological matter.
The researchers hope that this finding could also help in the search for life on other planets.
"These discoveries demonstrate life developed on Earth at a time when Mars and Earth had liquid water at their surfaces, posing exciting questions for extra-terrestrial life," Michael Dodd of University College London and first author of the paper published in Nature said. "Therefore, we expect to find evidence for past life on Mars 4,000 million years ago, or if not, Earth may have been a special exception."