Around 41,000 years ago, something strange happened to Earth’s magnetic field: the North Pole wandered over Europe, and the planet’s protective shield against solar radiation became much weaker.
This period, known as the Laschamps excursion, didn’t last forever—but while it did, the Earth’s magnetic field dropped to just 10% of its usual strength.
As a result, dangerous UV rays and cosmic radiation from the sun reached deeper into Earth’s surface than normal, possibly threatening life.
New research from the University of Michigan suggests that early Homo sapiens may have survived this event by using clever adaptations—like hiding in caves, making better clothing, and using ochre, a natural pigment, as a form of sunscreen.
Meanwhile, Neanderthals, who also lived in Europe at the time, may not have had access to these same protective strategies. By around 40,000 years ago, they had disappeared.
The study combined models of Earth’s magnetic field, the space environment, and historical auroras to create a 3D map showing how cosmic radiation affected different parts of the planet during the Laschamps event.
The results lined up surprisingly well with archaeological evidence showing an increase in cave use and ochre use by early humans during that same period.
Earth’s magnetic field is created by the spinning of molten iron in its core. This field acts like a protective bubble, shielding us from harmful particles coming from the sun.
When the magnetic poles move or flip, this shield weakens and allows more radiation to reach the surface. During the Laschamps event, auroras—normally seen only near the poles—would have appeared over much of Europe and even parts of Africa.
Lead researcher Agnit Mukhopadhyay, who works in climate and space sciences at the University of Michigan, explained that their model helped reveal where radiation could have reached the ground.
These high-radiation areas matched regions where early humans were especially active, suggesting they may have adapted their behavior to protect themselves.
Anthropologist Raven Garvey noted that Homo sapiens had tools that Neanderthals likely didn’t. These included scrapers, needles, and awls used for making fitted clothes—offering both warmth and possibly UV protection.
With better clothes, early humans could move farther from their shelters to find food. Ochre, often found at sites associated with Homo sapiens, was also likely used as a sunblock, based on its composition and how some cultures still use it today.
Although this research is not definitive, it presents a new way to understand the disappearance of Neanderthals and the survival of modern humans.
It also raises questions about what might happen if Earth experienced another magnetic field weakening today. According to Mukhopadhyay, such an event could disrupt satellites, telecommunications, and power grids.
Interestingly, this study also offers insights into the possibility of life on other planets. If humans could survive a period when Earth’s magnetic field was so weak, perhaps life could exist in harsher environments elsewhere too.
While we can’t be sure of every detail, this research helps piece together how ancient humans may have used creativity and innovation to survive one of Earth’s more dangerous natural events.
Source: University of Michigan.
