How Earth’s Faint Magnetic Field Fostered the Rise of Complex Life

Origin of Life Artist Concept

Between 591 and 565 million years ago, the Earth experienced an unprecedented weakening of its magnetic field, as analyzed from plagioclase crystals. This event coincided with a significant rise in oxygen levels in the atmosphere and oceans, potentially explaining the diversification of early complex organisms like the Ediacaran fauna. Researchers suggest that the reduced magnetic field might have facilitated increased oxygen by allowing more hydrogen to escape into space.

Research reveals that a weakened magnetic field between 591 and 565 million years ago might have triggered higher oxygen levels, aiding the development of complex life.

An unusual reduction in the strength of the Earth’s magnetic field between 591 and 565 million years ago coincided with a significant increase in the oxygen levels in the atmosphere and oceans, according to a paper published today (May 2) in Communications Earth & Environment. The authors propose that the weakening of the magnetic field may have led to the increase in oxygen, which is believed to have supported the evolution of some of the earliest complex organisms.

Ediacaran Fauna and Oxygen Increase

Between 600 and 540 million years ago, life on Earth consisted of soft-bodied organisms known as the Ediacaran fauna, the earliest known complex multicellular animals. The fossil record shows that these organisms significantly diversified in complexity and type between 575 and 565 million years ago. Previous research has suggested that this diversification is linked to a significant increase in atmospheric and oceanic oxygen levels that occurred over the same period. However, it is not yet clear why this increase in oxygen occurred.

Analysis of Plagioclase Crystals

John Tarduno and colleagues analyzed the magnetic properties of 21 plagioclase crystals, a common mineral in Earth’s crust, which were extracted from a 591-million-year-old rock formation in Brazil. Plagioclase crystals contain tiny magnetic minerals that preserve the intensity of the Earth’s magnetic field at the time they are formed. Analysis of the crystals showed that, at their point of formation, the Earth’s magnetic field was the weakest ever recorded — some 30 times weaker than both the current magnetic field intensity, and that measured from similar crystals formed approximately 2,000 million years ago.

Link Between Magnetic Field and Oxygen Levels

The authors combined their results with previous measurements to establish that the Earth’s magnetic field was at this weak level for at least 26 million years, from 591 to 565 million years ago. This overlaps with the rise in oxygen, which occurred between 575 and 565 million years ago. The authors propose that the weakened magnetic field may have allowed more hydrogen to escape to space, resulting in a greater percentage of oxygen in Earth’s atmosphere and oceans, which may in turn have supported the diversification in the types and complexity of organisms.

Reference: “Near-collapse of the geomagnetic field may have contributed to atmospheric oxygenation and animal radiation in the Ediacaran Period” by Wentao Huang, John A. Tarduno, Tinghong Zhou, Mauricio Ibañez-Mejia, Laércio Dal Olmo-Barbosa, Edinei Koester, Eric G. Blackman, Aleksey V. Smirnov, Gabriel Ahrendt, Rory D. Cottrell, Kenneth P. Kodama, Richard K. Bono, David G. Sibeck, Yong-Xiang Li, Francis Nimmo, Shuhai Xiao and Michael K. Watkeys, 2 May 2024, Communications Earth & Environment.
DOI: 10.1038/s43247-024-01360-4

1 Comment on "How Earth’s Faint Magnetic Field Fostered the Rise of Complex Life"

  1. It would have also led to dissociation of water into H2 and O quite possibly producing about 1000 tonnes of oxygen a day, or in 26 million years 9.49x 10 power 10 tonnes.If 1000 tonnes oxygen will keep 1 million H sapiens breathing for a day, then that could enhance the lifestyle of Ediacara-type fauna for quite a while. It would interesting to lean what the Earth’s magnetic field was doing about 2,4 billion years ago when oxygen first began poisoning the Earth’s atmosphere and bugs started going eukaryotic. I am happy to help someone, as co-author, write a learned academic paper……..

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