Can the collapse of a magnetic field explain the emergence of animals?

The Ediacaran period, which occurred between 635 and 541 million years ago, was a pivotal time in Earth’s history, marked by the emergence of complex, multicellular organisms that set the stage for the diversification and proliferation of life forms. Researchers at the University of Rochester recently discovered evidence suggesting that Earth’s magnetic field played an important role in the development of macroscopic animals during this period. The study, published in Nature Communications Earth & Environment, investigates how fluctuations in the ancient magnetic field could have affected oxygen levels on Earth, which in turn could have been crucial for the flourishing of life forms millions of years ago.

According to John Tarduno, professor of earth and environmental sciences at the University of Rochester, the Ediacaran fauna was among the most remarkable life forms of the Ediacaran period. These organisms resembled early animals; some grew to over a meter in size and showed mobility, indicating that they required more oxygen compared to previous life forms. The close timing of the emergence of these life forms with the ultra-low geomagnetic field led researchers to reexamine environmental factors, focusing on atmospheric and ocean oxygenation as potential drivers of life’s diversification during this period.

Earth’s magnetic field, which is generated by the churning of liquid iron in the planet’s outer core, is crucial for protecting the planet from solar wind and radiation. The strength of the magnetic field has varied over time, and there is evidence that it was unusually weak during the Ediacaran period. By studying ancient feldspar and pyroxene crystals from rocks, Tarduno and his team were able to reconstruct the strength of Earth’s magnetic field during this period. The data showed that the magnetic field was up to 30 times weaker than today and lasted for at least 26 million years.

A weak magnetic field can lead to the loss of hydrogen from Earth’s atmosphere, leaving more oxygen instead of reacting with hydrogen to form water vapor. This increased oxygenation of the atmosphere and surface ocean may have facilitated the emergence of more advanced life forms during the Ediacaran period. Tarduno and his team’s research suggests that the ultra-weak magnetic field during this period contributed to a gradual build-up of oxygen, allowing the diversification of life forms.

The study also highlights the potential impact of planetary interiors on the evolution of life. Tarduno suggests that understanding processes at Earth’s core could shed light on the potential for life beyond our planet, highlighting the links between planetary dynamics and the development of life. The research, supported by the US National Science Foundation, underlines the importance of studying Earth’s magnetic field in relation to the evolution of life and its broader implications for planetary science.