Life on Earth was already diverse more than 3.7 billion years ago!

At the beginning of the XX^and century, there was reason to believe that planets and, indeed, planetary systems must be rarities in the observable cosmos. We now know that they are almost inevitable around main sequence stars. What about the appearance of life on Earth? a huge fluke with a very slow evolution or on the contrary an equally inevitable and very rapid process, not only perhaps at the beginning of the Archean 4 billion years ago, but already only a few hundred million years ago years after the birth of our Blue Planet during the Hadean?

In 2017, a team that already included Dominic Papineau, currently working at Center for Planetary Sciences of the’UCL London Center for Nanotechnology, had made a spectacular announcement. Futura had talked about it in an article that we take up below and it was based on a publication in the famous newspaper Nature.

Geoscience researchers had studied rocks from the Nuvvuagittuq supracrustal belt (Nuvvuagittuq Supracrustal Belt or NSB in English) located in Quebec. The rocks had been collected in 2008 by Dominic Papineau. The NSB is also referred to as the Nuvvuagittuq Greenstone Belt. Located on the eastern shore of Hudson Bay, 40 km southeast of Inukjuak, Quebec, this rock formation composed of volcanic rocks mafic and ultramafic metamorphoses associated with sedimentary rocks is one of the oldest known on Earth.

It is estimated that there are rocks whose ages could be between 3.75 and 4.28 billion years. However, according to Dominic Papineau and his colleagues in 2017, some of these rocks also contain structures and chemical compounds that seriously suggest that they are microfossils. If this is indeed the case, life already existed at least 3.75 billion years ago on Earth and it would even have appeared 4 billion years ago, evolving rapidly to give the various microfossils that one seems to be observed in the rocks of the NSB.

This contradicts the current paradigm which considers that life could not have appeared until the beginning of the Archean and that it had not then had time to evolve much to give already diverse forms.

Biogenic or abiogenic structures?

Of course, potential microfossils have been found in rocks similar to those at the NSB for decades, testifying to an environment similar to that of the hydrothermal springs present-day oceans, an environment in which it is believed that life appeared by exploiting the chemosynthesislong before discovering the photosynthesis and then the use of oxygen.

Serious doubts have always been put forward on the biological origin of these microfossils or the associated chemical traces (see the explanations of Herve Martin below), and those of the NSB of Quebec were no exception to the rule. But, today, Dominic Papineau and his colleagues return to the subject with new arguments to try to convince the skeptics as we can read with a publication in Science Advances.

It was a question of trying to demonstrate that the filamentous structures already observed – reminiscent of populations of microorganisms already diversified by surprisingly rapid evolution more than 3.75 billion years ago — were not abiogenic products, such as seepage deposits of waters rich in iron heated by the magma in ancient rocks but subsequent to their formation.

The structures observed are indeed made of hematite, a form of iron oxide or rustand locked in quartz. Their study was repeated by cutting new sections about as thick as paper (100 microns) in the rocks collected in 2008. It was then easier to make comparisons with what can be observed with bacteria oxidizing iron located close to the systems of ventilation hydrothermal today.

As explained in the UCL press release accompanying the publication of the article by Dominic Papineau and his colleagues, these researchers were then clearly able to show that we were in the presence of forms truly equivalent to twisted filaments, with parallel branched structures and deformed spheres found in the rocks of present-day hydrothermal vents, for example near the underwater volcano Loihi near Hawaii.

Observation techniques using in particular X-rays and expert image processing with powerful computers confirmed that the hematite filaments were wavy and twisted, and contained carbon organic, characteristics shared with modern iron-eating microbes as the UCL press release still explains.

From all this data, the researchers deduced that, according to them, the hematite structures could not have been created by the compression and heating of the rocks much later, with a metamorphism which would have operated over the billions of years after the end of the Hadean.

Origin of life: the oldest fossils possibly found in Quebec

Article of Laurent Sacco published on 02/03/2017

For decades, geologists have discovered intriguing structures that suggest they are microfossils over 3.5 billion years old. Yet these findings are often disputed. The latest would beat all records: the supposed microfossils were found in Quebec, in rocks at least 3.77 billion years old.

The Earth’s geological records become more and more rare and more and more difficult to decipher when one goes back in time from the Archean, towards the Hadean. It is therefore particularly tricky to determine when theappearance of life on earth.

However, in 2008, researchers made a startling announcement. According to them, they had demonstrated that rocks present along the coast of Hudson Bay in northern Quebec — in an area called the “Nuvvuagittuq Greenstone Belt” (Nuvvuagittuq Supracrustal Belt, in English, or NSB) –, were in place about 4.3 billion years ago, or only a few hundred million years after the formation of the Earth.

Now, an international team of geoscience researchers has just published an article in Nature announcing the discovery of traces of life forms, in rocks in the same region of Quebec, which would be at least 3.77 billion years old, and perhaps more: up to 4.3 billion years. If so, it would be the oldest evidence of the existence of living organisms on Earth known to date.

Hydrothermal springs at the origin of life?

In this case, the researchers believe they have discovered microfossils, that is to say the fossilized remains of microorganisms. Previously, the record was held by similar remains found in Western Australia with an estimated age of 3.46 billion years (see also the article below about the possible discovery of fossilized remains of stromatolites built by cyanobacteria 3.7 billion years ago). The putative Nuvvuagittuq microfossils appear as tubes and filaments of hematite (a mineral based on iron oxide) found inside layers made of quartz.

If confirmed, this discovery would be interesting in more ways than one:

• Already, you should know that the Nuvvuagittuq Greenstone Belt contains sedimentary deposits and other rocks suggesting that it was formed in a volcanic zone similar to that where, today, we observe hot Springs hydrothermal. This can only strengthen in their belief those who think that life appeared in these hot springs.
• Finally, microfossils at least 3.77 billion years old, and perhaps a few hundred million years older, suggest that life appeared very quickly on Earth.
• As a bonus, we can also think that all this brings grist to the mill for those who think that life could have appeared very quickly on Marchwhen similar conditions prevailed there and there were abundant expanses ofliquid water and one volcanism asset.

Bacteria or mineral structures?

However, caution is called for. This is not the first time that structures reminiscent of the remains of filaments made up of fossilized cells have been discovered. In several cases, it was later realized that these structures may have been created by abiotic processes. It happened with so-called microfossils discovered in Australia.

Researchers are well aware of this. This is why they provided several arguments supporting the thesis that it is indeed microfossils, and not hematite concentrations produced by changes in pressure and temperature that the rocks containing them would have undergone.

These arguments are:

• First, the tubes and filaments have divisional characteristics that are similar to those of the tubes and filaments formed by chemotrophic bacteria from theoxidation iron and found today in the vicinity of hydrothermal vents.
• Finally, we find graphite and minerals carbonates and phosphates, also associated with living forms and their fossilized remains.

We bet at the very least that research will multiply in Nuvvuagittuq, in particular that carried out by exobiologists interested in the Martian environment.