At the beginning of the 20th century there was reason to believe that planets and even 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 stroke of luck with a very slow evolution or, on the contrary, an equally inevitable and very rapid process, not only perhaps at the beginning of the Archaean 4 billion years ago, but already only a few hundred million years ago after the birth of our Blue Planet during the Hadean?
In 2017, a team that included Dominic Papineau, who currently works at the UCL London Center for Nanotechnology’s Center for Planetary Sciences, made a spectacular announcement. Futura had talked about this in an article we pick up below, based on a publication in the famous journal Nature.
Geoscientific researchers had studied rocks from the Nuvvuagittuq supracrustal belt (Nuvvuagittuq Supracrustal Belt or NSB in English) in Quebec. The stones were collected by Dominic Papineau in 2008. The NSB is also known as the Nuvvuagittuq Greenstone Belt. Composed of metamorphosed mafic and ultramafic volcanic rocks associated with sedimentary rocks, this rock formation on the east shore of Hudson Bay, 40 km southeast of Inukjuak, Quebec, is one of the oldest known on earth.
A presentation of the discovery of possible microfossils dating back at least 3.75 billion years. For a fairly accurate French translation, click the white rectangle at the bottom right. Then the English subtitles should appear. Then click on the nut to the right of the rectangle, then on “Subtitles” and finally on “Translate automatically”. Choose French. © UCLTV
It is estimated that there are rocks that could be between 3.75 and 4.28 billion years old. However, according to Dominic Papineau and his colleagues in 2017, some of these rocks also contain structures and chemical compounds that seriously suggest they are microfossils. If this is indeed the case, life existed on Earth at least 3.75 billion years ago and would have originated as much as 4 billion years ago and would have rapidly evolved into the various microfossils that seem to be observed in the rocks of the NSB .
This contradicts the current paradigm, which assumes that life could not have arisen before the beginning of the Archaean, and that it did not then have time to evolve much to already give diverse forms.
Biogenic or abiogenic structures?
Of course, potential microfossils have been found in rocks similar to those at NSB for decades, suggesting an environment similar to hydrothermal vents in modern-day oceans, an environment where life is thought to exist using oxygen.
Serious doubts have always been expressed about the biological origin of these microfossils or the chemical traces associated with them (see explanations by Hervé Martin below), and those of the Quebec NSB have not usually escaped notice. But today Dominic Papineau and his colleagues return to the topic with new arguments to try to convince the skeptics, as we can read in a publication in Science Advances.
Have you ever seen dinosaur fossils that you hardly doubt exist or could have been abiotic? But what traces were left by bacteria that lived on earth more than 3.5 billion years ago? How do you find the oldest traces of life on earth? With Hervé Martin, geologist sadly deceased, explanations in 10 min. © French Exobiology Society
The aim was to show that the filamentous structures already observed – reminiscent of populations of microorganisms that were already diversified by astonishingly rapid evolution more than 3.75 billion years ago – were not abiogenic products such as infiltration deposits of iron-rich waters caused by magma in ancient rocks heated, but after their formation.
The observed structures are actually made of hematite, a form of iron oxide or rust, surrounded by quartz. Their study was renewed by cutting new sections about as thick as paper (100 microns) into the rocks collected in 2008. It was then easier to make comparisons with what can be observed today in oxidizing iron bacteria near hydrothermal vent systems.
As explained in the UCL press release accompanying the publication of the article by Dominic Papineau and his colleagues, these researchers were then able to show unequivocally that we were in the presence of forms truly equivalent to twisted filaments, with parallel branched structures and to distorted spheres were found in rocks of present-day hydrothermal vents, for example near the submarine Loihi volcano near Hawaii.
Observational techniques, particularly using X-rays and expert image processing using powerful computers, allowed confirmation that the hematite filaments were wavy and twisted and contained organic carbon, properties they share with the carbon-eating microbes of modern iron as always explained in the UCL press release .
From all this data, the researchers concluded that, in their opinion, the hematite structures could not have been formed much later by the compaction and heating of the rocks, with a metamorphosis that would have taken place during billions of years after the end of 2000 by the Hadeans .
By Hervé Cottin, Astrochemist, University Professor, Lisa, Université Paris Est Créteil/Université de Paris/CNRS Discover the website https://astrobioeducation.org/fr/ Are we alone in the universe? You may have already asked yourself the question… We find answers in films, literature or science fiction comics and our imaginations are populated by alien creatures! But what does science say about this? The AstrobioEducation website invites you to discover exobiology, an interdisciplinary science that aims to study the origin of life and its exploration elsewhere in the universe. Through an educational journey divided into 12 stages, researchers from different disciplines will help you understand how science works to answer the fascinating questions about the origin of life and its exploration elsewhere than on Earth. © French Exobiology Society
Origin of life: the oldest fossils possibly found in Quebec
Article by Laurent Sacco published on 02/03/2017
For decades, geologists have uncovered intriguing structures that suggest they may be microfossils over 3.5 billion years old. But these findings are often controversial. The latest would smash all records: the alleged microfossils were found in Quebec, in rocks at least 3.77 billion years old.
The geological records of the earth become increasingly rare and increasingly difficult to decipher as one goes back in time from the Archean to the Hadean. Therefore, it is particularly difficult to determine when life first appeared on Earth.
In 2008, however, researchers made a surprising announcement. According to them, they had demonstrated the presence of rocks along the coast of northern Quebec’s Hudson Bay — in an area called the “Nuvvuagittuq Greenstone Belt” (Nuvvuagittuq Supracrustal Belt, in English, or NSB) — around 4.3 billion years ago years, i.e. only a few hundred million years after the formation of the earth.
Now, an international team of geoscientific researchers has just published an article in Nature announcing the discovery of traces of life in rocks in the same region of Quebec that are at least 3.77 billion years old, and maybe longer: until until 4.3 billion years. If so, it would be the oldest known evidence of the existence of living organisms on Earth.
Hydrothermal vents at the origin of life?
In this case, the researchers believe they have discovered microfossils, i.e. 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 following article on the possible discovery of fossil remains of stromatolites built by cyanobacteria 3.7 billion years ago ). The putative Nuvvuagittuq microfossils are in the form of tubes and filaments of hematite (an iron oxide-based mineral) embedded in layers of quartz.
If confirmed, this discovery would be interesting in more ways than one:
- It should already be known that the Nuvvuagittuq Greenstone Belt contains sedimentary deposits and other rocks, suggesting that it may have formed in a volcanic zone similar to where we observe hydrothermal hot vents today. This can only encourage those who believe that life originated in these hot springs.
- After all, microfossils dating back at least 3.77 billion years and perhaps a few hundred million years older suggest that life appeared on Earth very quickly.
- As a bonus, we can also think that all of this provides grist to the mills of those who believe that life could have arisen very quickly on Mars if similar conditions existed there and there was plenty of liquid water and active volcanism.
Bacteria or mineral structures?
However, caution is advised. It is not the first time that structures reminiscent of thread remnants from fossilized cells have been discovered. In several cases it was later recognized that these structures may have arisen through abiotic processes. It happened with so-called microfossils discovered in Australia.
Researchers are well aware of this. Because of this, they provided several arguments supporting the thesis that these are in fact microfossils and not concentrations of hematite formed by changes in pressure and temperature to which the rock containing them would have been exposed.
These arguments are:
- First, the tubes and filaments have properties at the level of divisions that are similar to those of the tubes and filaments formed by bacteria that practice chemotrophy from the oxidation of iron and that are found today near hydrothermal vents.
- Finally, there is graphite and carbonate and phosphate minerals, which are also associated with living forms and their fossilized remains.
At the very least, we’re betting that research at Nuvvuagittuq will multiply, especially by exobiologists interested in the Martian environment.
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