The breakup of the ancient supercontinent Nuna around 1.5 billion years ago reshaped Earth's surface, reducing volcanic carbon emissions and expanding shallow seas that fostered oxygen-rich environments. Scientists from the University of Sydney and the University of Adelaide link this tectonic event to the rise of early eukaryotic life. Their study challenges the notion of a stagnant 'Boring Billion' period in Earth's history.
Between 1.8 and 0.8 billion years ago, Earth experienced the 'Boring Billion,' a time traditionally seen as geologically and biologically uneventful. However, new research published in Earth and Planetary Science Letters reveals dynamic plate tectonics drove profound changes. Lead author Professor Dietmar Müller from the University of Sydney stated, "Our approach shows how plate tectonics has helped shape the habitability of the Earth. It provides a new way to think about how tectonics, climate and life co-evolved through deep time."
The study focuses on the disintegration of supercontinent Nuna, which began about 1.46 billion years ago. This event more than doubled the length of shallow continental shelves to roughly 130,000 kilometers, creating expanded shallow-water zones. These areas supported oxygen-rich, temperate seas ideal for early complex organisms. Simultaneously, volcanic CO2 emissions decreased as more carbon was stored in ocean crust through interactions with hot rock at spreading ridges, leading to limestone deposits that locked away carbon.
Professor Müller explained, "Deep Earth processes, specifically the breakup of the ancient supercontinent Nuna, set off a chain of events that reduced volcanic carbon dioxide (CO2) emissions and expanded the shallow marine habitats where early eukaryotes evolved."
Co-author Associate Professor Adriana Dutkiewicz added, "This dual effect—reduced volcanic carbon release and enhanced geological carbon storage—cooled Earth's climate and altered ocean chemistry, creating conditions suitable for the evolution of more complex life."
The first fossil evidence of eukaryotes dates to about 1.05 billion years ago, coinciding with dispersing continents and spreading shallow seas. Associate Professor Juraj Farkaš from the University of Adelaide noted, "We think these vast continental shelves and shallow seas were crucial ecological incubators. 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."
By integrating plate tectonic models with carbon cycle simulations, the research connects deep-Earth movements to surface habitability, showing how even quiet periods prepared Earth for life's diversification. The findings appear in the journal as: R. Dietmar Müller et al., Earth and Planetary Science Letters, 2025; 672: 119683, DOI: 10.1016/j.epsl.2025.119683.