Orchestrated in MidJourney by TA 2023
Artistic recreation of primitive eukaryotic organisms that lived in the ocean
The rupture of Nuna, around 1.5 billion years ago, triggered three major changes: it created shallow seas, reduced the release of volcanic gases and confined carbon in ocean sediments – leading to a richer oxygen atmosphere and more temperate conditions.
The fragmentation of the ancient supercontinent Show drastically altered the planet, and this reorganization may have created the conditions that gave rise to complex life.
O “annoyed billions” refers to the period between 1.8 billion and 800 million years ago.
Although this interval encompassed the fragmentation and reconstitution of two ancient supercontinents, Nuna and Rodínia, scientists gave it this name due to the perception of a lack of major transformations.
There would have been a great interval of geochemical, climatic and biological stability in Earth’s history.
However, a new study, in Earth and Planetary Science Lettersrevealed that, After all, this period was less boringin terms of plate tectonics and evolutionary changes, than previously thought.
The new investigation revealed that Nuna’s rupture triggered a series of events that made the Earth more welcoming to life.
As fragments of Nuna moved away from the supercontinent’s core, shallow seas proliferated in the spaces between them — waters that are more temperate and rich in oxygen than previous oceans — revealed unprecedented simulations.
As detailed by , researchers have reconstructed the movements of tectonic plates and the associated changes in carbon storage and emission over the last 1.8 billion years in unprecedented detail.
Over 350 million years during the “boring billion”, the total length of shallow waters around continents doubled – reaching around 130,000 kilometers, the equivalent of more than three times the Earth’s circumference at the equator.
At the same time, the subduction zones — where one tectonic plate dips beneath another — shortened globally due to the way the plates were moving.
Subduction zones cause volcanic activity at the surface because they inject seawater that reduces the melting temperature of rocks in the Earth’s mantle – the layer beneath the crust. This facilitates the formation of magma, which then rises to the crust and erupts through volcanoes, along with debris and gases such as carbon dioxide (CO₂).
As the team explained, as subduction zones shortened, the amount of CO₂ released from the Earth’s interior into the atmosphere decreased. That cooled the planet and helped establish oxygen-rich conditions in the new shallow seas. These relatively stable ecosystems will have given origin of life forms more complex than those that existed until then.
The “incubators” of complex life
“We believe that these vast continental shelves and shallow seas were crucial ecological incubators”, said, in , the study’s co-author Juraj Farkašassociate professor in the School of Physics, Chemistry and Earth Sciences at the University of Adelaide, Australia, in a statement.
“They provided tectonically and geochemically stable marine environments, presumably with high levels of nutrients and oxygen, which, in turn, were fundamental for more complex life forms to evolve and diversify on our planet”, he concluded.
Shallow seas may have accelerated the diversification of eukaryotes —organisms whose cells have specialized structures called organelles and a membrane-bound nucleus that contains DNA.
All animals, plants and fungi are eukaryotes, so the appearance of eukaryotic cells during the “boring billion” was an essential step in the evolution of complex life.
