Ancient humans may have faced radiation risk 41,000 years ago
A weakening of Earth’s magnetic field known as the Laschamps event would have increased the threat of solar radiation, perhaps requiring ancient humans to invent protective measures
By James Woodford
16 April 2025
A magnetic field disturbance could have allowed auroras to occur more widely 41,000 years ago
EvgeniyQ/iStockphoto/Getty Images
Around 41,000 years ago, Earth’s magnetic field weakened to just a fraction of modern levels, leading to a huge increase in the radiation hitting the surface of the planet. Some researchers suggest the Laschamps event, as it is known, could have pushed Neanderthals towards extinction, while modern humans might have protected themselves using tailored clothing and ochre sunscreen.
Earth’s magnetic field extends into space and acts as a protective shield against harmful radiation. The magnetic poles usually line up with the north and south poles, but they occasionally wander due to changes in the liquid outer core of the planet.
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“Fluctuations in this system can lead to variations in the strength and orientation of Earth’s magnetic field, such as those observed during the Laschamps event,” says Agnit Mukhopadhyay at the University of Michigan.
By studying magnetic signatures preserved in volcanic rocks and sediments, Mukhopadhyay and his colleagues created a detailed 3D reconstruction of Earth’s magnetic field during the Laschamps event.
They found evidence that the magnetic poles had shifted towards the equator and that the field strength had weakened to just 10 per cent of today’s levels.
