Orbitally-Driven Nutrient Pulses Linked to Early Cambrian Periodic Oxygenation and Animal Radiation - Astrobiology

Orbitally Driven Nutrient Pulses and Early Cambrian Evolution

During the Cambrian Explosion, waves of rapid animal diversification coincided with repeated carbon-sulfur isotope shifts. These variations are believed to mirror fluctuations in atmospheric and shallow-marine oxygen levels that encouraged evolutionary expansion. Yet, the underlying cause of these oxygenation pulses had remained uncertain.

Researchers reveal that synchronized carbon-sulfur isotope cycles and marine oxygenation surges were likely triggered by long-period orbital forcing. This mechanism influenced continental weathering and nutrient delivery, impacting ocean chemistry and biological activity.

Modeling the Orbital Influence

By applying a combined climate-biogeochemical model driven by latitudinally resolved insolation data, scientists simulated long-term shifts in weathering, nutrient supply, and carbon burial. The results aligned with real-world isotope variations, reinforcing the link between orbital cycles and Earth's biogeochemical feedbacks.

"We conclude that the oxygen-driven evolutionary changes in the early Cambrian can be explained by recurrent nutrient inputs to the ocean, resulting from climate change caused by long-period orbital cycles."

Context and Contributors

The findings, published in Geophysical Research Letters, suggest that planetary orbital dynamics shaped Earth's early biosphere. The study was presented by an Explorers Club Fellow and former NASA Space Station Payload Manager and space biologist with field experience on Devon Island and at Everest Base Camp.

Author summary: Long-period orbital cycles controlled nutrient fluxes and oxygen levels in early oceans, fueling the evolutionary leaps of the Cambrian Explosion.

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astrobiology.com astrobiology.com — 2025-11-03

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