World’s oldest fossils could help find life beyond Earth

The study was published Wednesday in the journal Nature.

An worldwide team led by University College London scientists found tiny filaments and tubes formed by ancient bacteria encased in quartz layers from Quebec’s Nuvvuagittuq Supracrustal Belt (NSB), home to some of the oldest sedimentary rocks on Earth.

Dodd knew these conclusions would be controversial – and indeed, they are – so he and his co-authors looked for further evidence to bolster their case that what they found truly represents traces of ancient life. “It brings back the production of oxygen on the Earth’s surface, albeit by tiny amounts, to the beginning of the sedimentary record”, he said. But within some jasper in the hydrothermal vent layers, the researchers found tiny tubes and filaments filled with hematite, an iron oxide mineral.

But the scientists behind the new finding believe their analysis should hold up to scrutiny. They were found in some of the oldest sedimentary rock in the world, on the shoreline of Northern Quebec, near the Nastapoka Islands.

The researchers have provided a lot of solid evidence to support their claim for ancient life, Konhauser said.

Earth is thought to be about 4.57 billion years old. Like modern iron-dependent bacteria, they “would have literally “eaten” the iron … in the same sense that we eat cake”, Papineau says, adding the bacteria could have formed rust-colored mats like those seen today.

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. The chemical patterns they found look just like known deposits of vent-loving microbes in much more recent samples from other locations. We found these in the form of isotopically light carbon in graphite, associated with carbonate and apatite in and around the microfossils.

Rock containing tubular and filamentous microfossils.

Not everyone is so convinced. “The only thing that can do that is the biological explanation”. “Because if the context isn’t right than everything else you do doesn’t matter”.

So, although multiple individual lines of evidence do point to the structures being evidence of life, the problem occurs when they try to weave those pieces of evidence into a complex story, Konhauser said. This also shows that hydrothermal vent environments were also one of the first, if not the first, places occupied by life on Earth. Some of that carbon is inside crystals of phosphorus-rich minerals, which also hints at early biology.

Bosak was also skeptical of the stated minimum age for the fossils.

The rock in question is a 3-kilometre-long swathe on the eastern shores of the Hudson Bay called the Nuvvuagittuq Greenstone Belt. It is also bisected by veins of igneous, or volcanic, rock that intruded into the sediments during this process.

The ancient fossils were found in iron-rich rocks in the Nunavik region of Québec, Canada.

Of course, it’s best not to get too carried away in daydreams until we’re more certain about what the researchers have found in these Canadian rocks.

Together, this evidence very clearly demonstrates a strong biological presence in the 3,770m- to 4,280m-year-old rocks, pushing back the date of the earliest known microfossils by 300m years.

The fossils were the oldest-known evidence of microbes on the planet at the time, prompting scientists to say the discovery had “staggering” implications for the history of life on Earth.

Scientists discovered a 3.7-billion-year-old fossil fossil that could hold the key to the development of life on Mars.

Though those structures, called stromatolites, may be similar in age to Dodd’s microfossils, they came from an entirely different environment: shallow marine waters, perhaps touched by sunlight.

When life first emerged on Earth has been an enduring and frustrating mystery. Could it be, in the words of Nobel laureate Christian de Duve, a “cosmic imperative?” If confirmed, the find will open new avenues to the search for life on Mars and other planets.