Sunscreen, Apparel, and Caves Could Have Provided Modern Humans an Advantage Over Neanderthals During Shifts in Earth’s Magnetic Field

Photo credit: www.smithsonianmag.com

A new study indicates that the extinction of Neanderthals closely correlated with a geomagnetic shift that increased radiation exposure to Earth’s surface. Early humans, it seems, may have been better equipped to handle these changes.

Margherita Bassi – Daily Correspondent

April 21, 2025 4:54 p.m.

One of the pivotal mysteries in the study of human evolution is the complete disappearance of Neanderthals, our closest extinct relatives, approximately 40,000 years ago. Researchers have proposed various explanations for their extinction, such as climate shifts, competition for resources, and genetic dilution through interbreeding with modern humans.

Recent research suggests that early *Homo sapiens* had advantages that Neanderthals lacked, particularly in their use of natural protective measures against heightened solar and cosmic radiation during a significant geomagnetic event. This study, published in *Science Advances*, sheds light on how these adaptations may have facilitated human survival.

The Earth’s magnetic field, generated by movements within the planet’s molten core, serves as a protective barrier against harmful radiation from space. This invisible shield, influenced by the alignment of the magnetic poles, protects the atmosphere and life on Earth. However, the magnetic poles occasionally shift from their geographic positions—a phenomenon known as geomagnetic excursions. Throughout Earth’s history, there have been about 180 such events, with the most recent, known as the Laschamps excursion, occurring around 41,000 years ago, just prior to the extinction of Neanderthals.

To explore the impact of the Laschamps excursion, an international research team developed a sophisticated 3D model to simulate the conditions of Earth’s upper atmosphere and space during this period. Their analysis revealed that during the excursion, the strength of Earth’s magnetic field diminished dramatically, allowing for greater exposure to cosmic radiation as the north magnetic pole drifted over Europe, illuminating the night sky with auroras.

Lead author Agnit Mukhopadhyay, a climate and space scientist at the University of Michigan, noted that this weakened magnetic field and the resulting pole shifts created an expansive auroral zone. This scenario increased the infiltration of high-energy particles, which are known to pose health risks due to their ionizing properties.

Coinciding with the Laschamps event, early human populations began developing protective behaviors. The evidence suggests that *Homo sapiens* started crafting tailored clothing, utilizing caves for shelter, and increasingly applying ochre, a mineral with potential sunscreen-like properties. Co-author Raven Garvey highlighted that while direct observation of behaviors from over 40,000 years ago is impossible, the anticipated use of ochre for sun protection is plausible based on ethnographic studies of contemporary populations.

As Mukhopadhyay emphasizes, these environmental transformations might have encouraged adaptive strategies among human populations, such as better clothing and the strategic use of ochre to mitigate UV exposure. However, while *Homo sapiens* seemed to thrive during these changes, Neanderthals ultimately disappeared, which the researchers speculate could be linked to their lack of similar adaptive strategies.

Nevertheless, some experts stress caution in attributing the extinction of Neanderthals to these factors alone. Archaeologist Amy Mosig Way pointed out that while there is a temporal overlap between modern human migration into Europe and the Laschamps event, asserting that tailored clothing significantly contributed to the ability of early humans to outcompete Neanderthals might be an overreach.

On a broader scale, the research findings may have implications for understanding the conditions required for life on other planets. Mukhopadhyay remarked on the importance of studying prehistoric Earth events, noting that life can persist even under harsh conditions created by a weakened magnetic field. This perspective could enhance our understanding of exoplanetary systems and the potential for extraterrestrial life.

Source
www.smithsonianmag.com