The Ediacaran Period, which occurred between 635 to 541 million years ago, was a crucial 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 from the University of Rochester have recently discovered evidence suggesting that Earth’s magnetic field played a significant role in the development of macroscopic animals during this period. The study, published in Nature Communications Earth & Environment, explores how fluctuations in the ancient magnetic field may have influenced oxygen levels on Earth, which in turn could have been crucial for the thriving of life forms millions of years ago.
According to John Tarduno, a professor in the Department of Earth and Environmental Sciences at the University of Rochester, the Ediacaran fauna were among the most remarkable life forms from the Ediacaran Period. These organisms bore resemblance to early animals, some growing to over a meter in size and displaying mobility, indicating a need for more oxygen compared to earlier life forms. The close timing of the emergence of these life forms with the ultra-low geomagnetic field led researchers to revisit environmental factors, focusing on atmospheric and ocean oxygenation as potential driving forces behind the diversification of life 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 shielding the planet from solar wind and radiation. The strength of the magnetic field has varied over time, with evidence suggesting 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 revealed that the magnetic field was up to 30 times weaker than it is today, lasting for at least 26 million years.
A weak magnetic field can lead to the loss of hydrogen from Earth’s atmosphere, allowing more oxygen to remain 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. The research conducted by Tarduno and his team suggests that the ultraweak magnetic field during this time period contributed to a gradual buildup of oxygen, enabling 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 in Earth’s core could shed light on the potential for life beyond our planet, emphasizing the connections between planetary dynamics and the development of life. The research, supported by the US National Science Foundation, underscores the importance of studying Earth’s magnetic field in relation to the evolution of life and the broader implications for planetary science.