Oldest Fossils Ever Found Give New Clues to Life's Origins

An global team of scientists has discovered what they believe are the fossilised remains of microorganisms that would have clustered around a hot, seafloor vent. Earth itself is believed to have formed just 4.5 billion years ago.

The team contends that these bear more than a passing resemblance to the networks of bacteria that live in hydrothermal vents-towering, crenellated structures, pictured above, that form in the deep ocean above the boundaries between tectonic plates, where superheated mineral-laden water spurts up from beneath the seabed. In the modern ocean, life thrives in and around the vents that form near seafloor spreading ridges or subduction zones-places where Earth's tectonic plates are pulling apart or grinding together.

First author and PhD student Matthew Dodd added: "The most exciting thing about this discovery is that we now know that life managed to get a grip and start on Earth at such an early time of the planet's evolution, which gives us exciting questions as to whether we are alone in the solar system or in the universe and if life came so quickly, could we expect it to be a simple process on other planets as well?"

A team of worldwide scientists has found the oldest record of life on Earth in Northern Quebec, dating back at least 3.8 billion years.

Before this discovery, the oldest confirmed life on Earth was dated to 3.4 billion years ago, leading scientists to speculate that life probably started around 3.7 billion years ago. And scientists have found other potential signs of life around hydrothermal vents in Greenland from 3.8 billion years ago.

Ancient bacteria formed these iron oxide inclusions in hydrothermal vent deposits in the Nuvvuagittuq Supracrustal Belt in Québec, Canada.

Video As far as we know, almost four billion years ago nothing walked the lands of Earth, but there was life in the seas.

His next step is to travel to similarly old rock sites around the planet and suss out the origin of their organic matter.

Like all such ancient rocks, they have been heavily altered.

The team also found that the mineralized fossils are associated with spheroidal structures that usually contain fossils in younger rocks, suggesting that the hematite most likely formed when bacteria that oxidized iron for energy were fossilized in the rock.

Dodd says their findings mesh well with life starting at a hydrothermal vent.

If this is indeed evidence of the earliest known life on Earth, then it suggests the simplest organisms could emerge on a planet nearly immediately, in geological terms.

As with all such claims about ancient life, the study is contentious.

"It provides us with this high degree of certainty that these structures are indeed, biological microorganisms that were living and thriving around hydrothermal vents billions of years ago", he says.

If the researchers are right about what they've found, this would be the oldest direct evidence of life we've ever seen. The first is the presence of calcium- and carbon-based minerals such as graphite, apatite, and carbonate.

Dodd says the rocks around the fossil-containing layers contain chemical signatures of a hydrothermal vent.

The finding makes it considerably more likely that life has existed on Mars - where the key ingredient of liquid water arrived at about the same time as it did on Earth - and elsewhere.

Today those rocks are found in exposed glacier-polished outcrops that protrude from the lichens and other vegetation of the Northern Quebec tundra.

"I'm skeptical about the interpretations in the paper", she said. That is understandable. It is often hard to prove that certain structures could not also have been produced by non-biological processes.

The images showed clusters of tubes that resembled those similar to structures formed by modern deep-sea microbes.

  • Tracy Ferguson