A team of scientists discovered a “lost world” of ancient ancestors in billion-year-old rocks

At least 1.6 billion years ago, microscopic organisms lived in water, whose molecular fossils have been found in rocks from that time and may be the oldest traces of our lineage.

Its discovery Microscopic “Lost World”Publishes today Nature, We can change the understanding of our ancestors.

All organisms with eukaryotic cells (animals, plants, and fungi that contain DNA through a membrane) They have a first common ancestor called LECAIt lived about 1.2 billion years ago, but must have been preceded by other forms of eukaryotes.

A group Australian, French and German researchers Proterozoic (2,500 million to 542 million years ago) rocks have found abundant protosteroids, primordial compounds that had previously been overlooked as fossil evidence of primitive life.

Those biomarker signatures are indicative The existence of a whole series of previously unknown organisms that dominated complex life on Earth and lived at least a billion years before any animal or plant appeared.

A team led by Jochen Brocks of the Australian National University (AUN) has discovered the existence of these microscopic organisms that are part of eukaryotic organisms, commonly named “protosterol biota”.

“Molecular remains of protosterol biota found in 1.6-billion-year-old rocks seem to be the oldest traces of our own ancestry: they lived before the LECA”Benjamin Nettersheim, who signed up at the University of Bremen (Germany), pointed to another.

These organisms, which flourished from about 1.6 billion years ago to about 800 million years ago, were abundant in marine ecosystems around the world and may have shaped ecosystems for much of Earth’s history.

Although it is not known what they looked like, Brocks noted in his university report that they would have been more complex and presumably larger than bacteria: “We think they may have been Earth’s first predators, hunting and eating bacteria.”.

They differ from complex eukaryotic life (animals, plants and algae) in their cellular structure and perhaps their metabolism, which adapted to a world with much less oxygen in the atmosphere, the center said. German Research Center for Geosciences (GFZ).

I don’t know when They switched off Although these early humans, which point to the Tonic period, highly advanced eukaryotes began to flourish, such as fungi and algae.

“For our mammalian ancestors to grow large and abundant, the protosterol biota had to die out a billion years ago to make room for modern eukaryotes, just as the dinosaurs went extinct,” Brocks said.

To make the discovery, the researchers analyzed fossil lipid molecules known as protosteroids, which were unearthed from a 1.6-billion-year-old sedimentary rock that formed on the sea floor near Australia from the mid-Proterozoic.

The molecules had a primordial chemical composition, pointing to the existence of primitive complex organisms that had evolved and died out before the LECA. Without these biomarkers, “we wouldn’t have known that the protosterol biota existed, and scientists have overlooked these molecules for four decades because they don’t fit into conventional molecular search images,” says Nettersheim.

But once they knew what they were looking for, they found that dozens of other rocks, taken from billion-year-old streams around the world, “extruded similar fossil molecules.”

1958 Nobel Prize in Medicine Konrad Bloch predictedIn 1994, the existence of primitive molecules of this type, so these findings would prove him right.

However, he assumed that these intermediate protomolecules would never be found because they would not survive in the geological record, although this research now indicates that this is not the case and suggests that the remains of protosteroids may have remained in the rock for over a billion years.

(with information from EFE)

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