Ann Arbor Times

Ancient Homo sapiens may have used sunscreen, tailored clothes, and caves to their advantage during a geomagnetic event 41,000 years ago, according to research from the University of Michigan. This study published in Science Advances reveals that these adaptations might have helped Homo sapiens survive increased solar radiation while Neanderthals, lacking such technologies, saw their numbers dwindle around 40,000 years ago.

The research highlights that the North Pole's shift over Europe led to a weakened magnetic field, permitting more UV light to penetrate and become widespread. Agnit Mukhopadhyay, lead author and U-M research affiliate, noted, “In the study, we combined all of the regions where the magnetic field would not have been connected, allowing cosmic radiation...to seep all the way in to the ground.”

Researchers found that Homo sapiens began using ochre, providing sun protection, and tailored clothes more frequently during this period, potentially aiding their expansion across Europe and Asia as Neanderthal populations declined. Raven Garvey, U-M associate professor of anthropology, explained that clothing, offering warmth and protection from solar damage, played a significant role.

The geomagnetic changes resulted from the Earth's molten core movements creating a magnetic field, a crucial shield against cosmic radiation. Mukhopadhyay employed the Space Weather Modeling Framework to explore these interactions, which are said to cause auroras at the North and South poles. “Geomagnetic excursions,” such as the Laschamps excursion 41,000 years ago, temporarily weakened this field.

In collaboration with Sanja Panovska from Germany's GFZ Helmholtz Centre for Geosciences, Mukhopadhyay developed a 3D model of Earth's geospace system. The model indicated significant magnetic reduction during the Laschamps excursion, aligning with human behavioral changes. “What some of the differences are between these species...has been a major anthropological question for decades,” said Garvey.

Tailored clothing, along with sun-protective ochre use, may have given Homo sapiens an edge. Garvey mentioned that ochre has "sunscreen-like properties," suggesting its dual use in prehistoric times. The study's authors advise caution, underscoring that findings are correlational. However, the research offers insights into past geomagnetic impacts and potential future scenarios.

“If such an event were to happen today, we would see a complete blackout in several different sectors,” Mukhopadhyay warned, pointing out the disruptions in communication and telecommunication systems. The study underscores humanity's resilience in historically different environmental conditions, inviting reflection on life sustainability on exoplanets.

Co-authors include Michael Liemohn, Daniel Welling, and Austin Brenner of 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.