Did a slowing Earth allow life to finally breathe?

Science · Published 8 October 2026 Swipe more like this →

In short: Oxygen is the fundamental fuel for complex life, but the atmosphere didn't always have it in abundance. New research suggests that Earth's slowing rotation may have been the hidden driver, changing how microbial mats buried carbon and fundamentally altering the planet's chemistry.

For billions of years, Earth's rotation has been gradually slowing due to tidal friction. While we experience a 24-hour day today, the planet's rotation period may have been as short as 6 hours more than 4 billion years ago. This means the length of a single day—the diel period—has increased more than threefold since photosynthesis first emerged. This deceleration is primarily driven by tidal friction. Consequently, the duration of the illumination period has expanded significantly since the dawn of photosynthesis.

This change in daylength may have been a critical factor in the Great Oxidation Event (GOE) approximately 2.4 billion years ago, as well as the Neoproterozoic Oxygenation Event (NOE) around 600 million years ago. Scientists are investigating a mechanistic link between these oxygenation pulses and the slowing of the planet's rotation. Researchers are exploring how these specific oxygenation patterns correlate with the planet's rotational speed. This study examines a previously overlooked connection between these two phenomena.

The mechanism lies in the behavior of Precambrian benthic ecosystems, specifically cyanobacterial mats. While the total amount of photosynthesis (gross photosynthetic production) depends on light intensity, the net burial of organic carbon depends on illumination dynamics. Longer days change the balance between aerobic and anaerobic processes, increasing the export of oxygen from these microbial mats and enhancing the burial of organic carbon. The net productivity of these ancient ecosystems is influenced by the movement of metabolic substrates. These processes are largely regulated by molecular diffusion within the mats.

By burying more organic carbon, these ecosystems prevented it from being consumed and recycled, allowing free oxygen to accumulate in the atmosphere and oceans. This shift in chemistry helped pave the way for the evolution of the complex plants and animals that inhabit our modern world. This accumulation of oxygen was essential for the rise of aerobic life. Such chemical shifts were vital for the development of modern biological complexity.

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