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Weird and complex life emerged on Earth as the planet's magnetic field gave way

The Earth’s magnetic field protects life, but an ancient phase when it nearly collapsed coincided with a key step in evolution, says University of Rochester geophysicist John A. Tarduno.

Apr 8, 2025

1 min

The Earth’s magnetic field plays a key role in making the planet habitable. It shields lifeforms from harmful solar and cosmic radiation. It helps limit erosion of the atmosphere and keeps water from escaping into space.


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But new data show a prolonged near collapse of Earth’s magnetic field that took place some 575-565 million years ago coincided with the blossoming of macroscopic complex animal life.


We now face the possibility of a new, unexpected twist in how life might relate to the magnetic field, says John A. Tarduno, the William R. Kenan Professor of Geophysics and the dean of research at the School of Arts and Sciences and the Hajim School of Engineering and Applied Sciences at the University of Rochester.


“That twist could reach deep into Earth’s inner core,” says Tarduno, who recently wrote about the findings for Physics Today magazine.


Tarduno is frequently cited by news outlets, like CNN, The Washington Post, and Smithsonian magazine, on matters related to the Earth’s inner core, or dynamo, and magnetic field. He can be reached at john.tarduno@rochester.edu.


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