Around 41,000 years ago, a powerful magnetic shift weakened Earth’s natural shield against space radiation, and early humans turned to simple survival tools – using ochre as a natural sunscreen, wearing protective clothes, and sheltering in caves – to endure the changing environment. This may have helped Homo sapiens survive – while Neanderthals vanished.
The study, published in Science Advances, examines a dramatic event known as the Laschamps excursion.
During this event, Earth’s magnetic poles temporarily shifted, and the magnetic field dropped to just 10% of its normal strength. This allowed ultraviolet radiation to reach Earth’s surface and caused auroras to appear far beyond the poles, even across Europe and northern Africa.
Researchers suggest that early Homo sapiens responded with protective strategies: taking shelter in caves, wearing body-fitting clothes, and applying ochre to their skin—a natural pigment that may have worked like sunscreen.
The study’s lead author, Agnit Mukhopadhyay, a University of Michigan research affiliate in climate and space sciences, said, “We found that many of those regions actually match pretty closely with early human activity from 41,000 years ago.”
Mukhopadhyay further added that they saw “specifically an increase in the use of caves and an increase in the use of prehistoric sunscreen.”
The study draws a comparison between Homo sapiens and Neanderthals, who coexisted in Europe during this period. While modern humans arrived around 56,000 years ago, Neanderthals disappeared by 40,000 years ago. Their decline, researchers say, may be tied to the absence of these basic protective behaviors.
Raven Garvey, associate professor of anthropology at the University of Michigan, believes clothing could have been a key factor in human survival.
At archaeological sites linked to modern humans, researchers have found sewing tools like needles, scrapers, and awls – used to make fitted garments. These clothes kept people warm and allowed them to explore farther from shelters in search of food.
Garvey added that tailored clothing also protects the skin from solar radiation, which can cause serious health problems such as eye damage and folate depletion – a condition linked to birth defects and increased infant mortality.
Early humans also increased their use of ochre during this time. The red pigment, made of iron-rich clay, was widely used for painting and body decoration.
“There have been some experimental tests that show it has sunscreen-like properties,” Garvey said. “It’s a pretty effective sunscreen, and there are also ethnographic populations that have used it primarily for that purpose.”
Its growing use during the Laschamps event – especially among Homo sapiens – points to its potential role as an ancient form of sunblock.
To better understand the impact of the magnetic shift, Mukhopadhyay and his team created a 3D model of Earth’s space environment during the Laschamps event. They worked with Sanja Panovska from Germany’s GFZ Helmholtz Centre for Geosciences.
The team combined three models: one to reconstruct Earth’s magnetic field at the time, another to show how solar particles moved through space, and a third to estimate where auroras would have appeared. The final 3D view revealed areas where radiation likely reached the ground.
If the same kind of magnetic event occurred now, Mukhopadhyay warned, the damage would be widespread. “We would see a complete blackout in several different sectors,” he said.
“Our communication satellites would not work. Many of our telecommunication arrays, which are on the ground, would be severely affected by the smallest of space weather events, not to mention the human impacts, which would also play a pretty massive role in our day-to-day lives.”
The study also raises questions about life on other planets. Some scientists believe a strong magnetic field is necessary to protect life, but this research suggests otherwise.
Garvey explained that life did exist under extreme conditions. It just looked different from what it does today. “Looking at prehistoric Earth, and especially at events like this, helps us study exoplanetary physics from a very different vantage point.”
The research team included Michael Liemohn, Daniel Welling, and Austin Brenner from Michigan Engineering; Natalia Ganjushkina of both Michigan Engineering and the Finnish Meteorological Institute; Ilya Usoskin of the University of Oulu; and Mikhail Balikhin of the University of Sheffield.
