| Need another reason to apply sunscreen this summer? Consider how poorly the Neanderthals protected their skin and look what happened to them. Granted, much has changed in the 40,000 years since our closest human cousins went extinct. For one, Earth’s magnetic poles are back to normal again, creating a potent magnetic field that blocks out much of the sun’s never-ending barrage of charged particles. Back then, the North and South poles drifted toward the equator and other magnetic poles gained in prominence, causing chaos in the magnetosphere, which fell to about 10% of its current strength. The Earth fell prey to the sun’s full onslaught, giving rise to aurora events like the Northern Lights even along the equator. Meanwhile, ultraviolet light poured into many locations, including Western Eurasia, where both Neanderthals and early modern humans lived, according to a new paper published in the journal Science Advances. That excess radiation probably caused spikes in infant mortality, skin cancer and other maladies among the two groups, according to the research. Yet while Neanderthals soon died off, our early ancestors survived. Why, exactly? For one thing, better sun protection, perhaps. That 2,000 year long geomagnetic era — known to scientists as the Laschamps event — coincided with the rise of a culture in Western Eurasia in which early modern humans increasingly made cave art using ochre, which may have been used as a primitive form of sunscreen. They also developed tools such as needles made of bone for tailoring clothes, enabling better freedom of movement. Neanderthals, meanwhile, probably wore simple, draped clothing like capes, which might have kept them closer to home. “It is possible that topical sunscreens and tailored clothing provided anatomically modern humans essential photoprotection and access to resources,” the paper states. Lead author Agnit Mukhopadhyay, a researcher from the University of Michigan, is quick to point out that many factors probably contributed to Neanderthals’ demise. And he credits earlier research with raising the prospect of a link between the weaker magnetic field and big-deal terrestrial events. These include the disappearance of Australia’s megafauna — animals that roamed the Earth during the Ice Age, which included a six-meter-long lizard and a wombat-like creature that weighed 2.5 tons. His work introduces complex computer modeling to the field of research, generating maps of how the Earth’s magnetic field looked at various points during those critical centuries. It shows where and when auroras probably appeared and ultraviolet light likely pounded the planet’s surface. That could inform future studies of what contributed to major changes in life on Earth, he says. This sort of geospace modeling serves modern needs, too. It helps predict when and where the Earth will get hit with abnormal levels of solar particles, which can cause disruptions to our satellites, communication channels and electrical grids. While no expert on ancient humans, Mukhopadhyay nonetheless likes to ponder what people 40,000 years ago must have thought when looking up at the night sky and seeing streaks of blue, green, red and yellow. He first saw the Northern Lights for himself last spring in Montreal. “It was a surreal experience,” he recalls, “to look at something that you have only seen in textbooks, that you have only seen in your studies, that you have actually written a dissertation on.” Oh, and one more thing. Wear sunscreen this summer, he says. | 
