'Boring Billion' not so boring - Scientists discover massive event switched things up on ancient Earth

Earth had a Boring Billion period during which time it had the enormous supercontinent Nuna, the first ever hypothesised. Research has found that when this ancient body started breaking apart, it gave rise to complex life. The "Boring Billion" is the period between 1.8 billion and 800 million years ago. During this time, Nuna broke apart, and some time and, its pieces joined together to form Rodinia, the next supercontinent. But besides this, nothing major was believed to have changed on Earth, and so it was given the name "boring." However, researchers have now found that it wasn't as plain as initially thought. According to the study published on October 27 in the journal Earth and Planetary Science Letters, the breakup of Nuna triggered a chain reaction that made Earth more hospitable to life. The gaps that appeared from the drifting apart of land masses led to shallow seas cropping up in the gaps. These seas were more temperate and oxygen-rich than the oceans.

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Shorter subduction zones during Boring Billion changed how life evolved

The researchers created a simulation of tectonic plate movements and how that changed carbon storage and emissions over the past 1.8 billion years. For 350 million years during the Boring Billion, shallow seas spread for over 130,000 kilometres, more than three times Earth's circumference at the equator. The shifting of the plates shortened the subduction zones, the place where one tectonic plate dives beneath another. In these zones, volcanoes inject seawater into Earth's mantle, which lowers the melting temperature of rocks. This leads to the formation of magma, which rises and erupts along with debris and gases such as carbon dioxide (CO2).

However, as subduction zones shortened, the amount of CO2 escaping from Earth's interior into the atmosphere also decreased. The planet cooled, creating oxygen-rich conditions in the shallow seas that formed following the breakup of Nuna. The researchers suggest that this gave rise to more complex life on Earth, which did not exist earlier. "We think these vast continental shelves and shallow seas were crucial ecological incubators," study co-author Juraj Farkaš said in a statement. "They provided tectonically and geochemically stable marine environments with presumably elevated levels of nutrients and oxygen, which in turn were critical for more complex lifeforms to evolve and diversify on our planet."

This particularly sped up the diversification of eukaryotes, and today, all animals, plants and fungi are eukaryotes. This led to the evolution of complex life during the Boring Billion, the study states.