Latest news with #AgnitMukhopadhyay
Yahoo
25-04-2025
- Science
- Yahoo
Ancient Body Paint May Have Been Prehistoric Sunscreen, Study Says
Ochre body paint may have been a form of prehistoric sunscreen that helped early humans survive a sudden increase in ultraviolet (UV) radiation around 41,000 years ago. That's a fascinating new hypothesis recently put forward by an international team of geoscientists and anthropologists, led by researchers at the University of Michigan. Their study reconstructs the global space environment during the end of the Last Glacial Period, and it finds that when Earth's magnetic field suddenly hiccuped all those millennia ago, it had a profound impact on our planet's protective solar shield. Scientists already knew of this distinct geomagnetic tantrum in Earth's history, called the Laschamp event, when the poles suddenly and briefly went haywire and underwent a partial flip before settling back into their original positions. But the new model is more detailed than ever before, and it shows that over the course of thousands of years, while the event was underway, the strength of Earth's geomagnetic field plummeted, reaching just 10 percent of what it is today. At the same time, the poles where magnetic field lines meet expanded and tilted by over 75 degrees relative to Earth's rotational axis. The South Pole shifted away from Antarctica and settled over Australia and New Zealand, while the North Pole wandered out of the Arctic into Western Eurasia, Northern Africa, and the northwestern Sahara. "Vast expanses of both hemispheres were enveloped by expansive open field line regions, unleashing a substantial barrage of auroral precipitation on a global scale," the authors write. That's where the sunscreen comes in handy. Auroras are caused by charged particles from the Sun, which are guided along Earth's magnetic field lines to the poles, where they are dumped out and interact with our planet's atmosphere. If the magnetic field lines are weakened, though, all that cosmic radiation enters the atmosphere earlier and deeper, which can be disastrous for the ozone layer below. As this protective layer weakens, it in turn admits more harmful UV light. During the Laschamp weakening, if some parts of the world let in more UV radiation, then early humans, including our own species and Neanderthals, were likely affected. Scientists have previously suggested our species' adaptations to the Laschamp event may have allowed us to survive where other humans could not. The new study, led by space physicist Agnit Mukhopadhyay, adds to that idea. "In the study, we combined all of the regions where the magnetic field would not have been connected, allowing cosmic radiation, or any kind of energetic particles from the Sun, to seep all the way in to the ground," explains Mukhopadhyay. While speculative, the authors point out that many of the areas likely exposed to increased ultraviolet radiation matched closely with changes in human activity more than 40,000 years ago, including more tools for tailoring clothing, an increase in cave art, and the use of ochre, which some studies suggest is a natural prehistoric sunscreen. These behaviors may reflect humanity's attempt to minimize exposure to ultraviolet radiation. To this day, the Himba community in northern Namibia, for instance, use ochre as sunscreen, and Indigenous Australians have similar customs. "There have been some experimental tests that show [ochre] has sunscreen-like properties. It's a pretty effective sunscreen, and there are also ethnographic populations that have used it primarily for that purpose," confirms anthropologist Raven Garvey of the University of Michigan. "Its increased production and its association primarily with anatomically modern humans (during the Laschamp) is also suggestive of people's having used it for this purpose as well." The timing is certainly intriguing, but the fossil record is not a complete one, and it needs to be interpreted with caution. There are likely many factors that led to our species' survival – and to the demise of our cousins. The disappearance of the Neanderthals, for instance, largely coincides with the Laschamp event, which has led some to propose that it is what killed our early relatives. Today, however, there is now some archaeological evidence of Neanderthals making tools for clothing, using ochre, and making cave art. Perhaps they didn't do this to the same level of sophistication as our own species, but they may have been adapting to the times, too. Historically, scientists have tended to underestimate our ancient cousins and what they were capable of. In 2021, archaeologist Anna Goldfield wrote a piece for Sapiens that argued that "headlines trumpeting that a magnetic pole switch killed off our ancient relatives are vastly oversimplifying the tremendously complex system in which Neanderthals and our Homo sapiens ancestors lived." The new study was published in Science Advances. Scientists Discover First Probable Evidence of a Roman Fighter Mauled by a Lion Scientists Say They Found a New Color Humans Have Never Seen Before Mysterious Antikythera Mechanism May Actually Be a Toy, Study Says
Yahoo
21-04-2025
- Science
- Yahoo
Sunscreen may have contributed to ancient humans' survival
(NewsNation) — Research from the University of Michigan shows that ancient Homo sapiens may have benefitted from the use of a prehistoric sunscreen during the shifting of the magnetic North Pole over Europe. Ancient humans used ochre, a mineral with sun-protective properties when applied to the skin. Other ways they protected themselves from harmful solar radiation include tailored clothes and the use of caves. The research team found that the North Pole wandered over Europe when the magnetic field's poles started to flip positions, a natural process that has happened around 180 times over Earth's geological history. The magnetic reversal didn't occur, but the magnetic field weakened, allowing aurora to appear over most of the globe and increasing the amount of harmful UV light from space. Scientists find strongest evidence yet of life on an alien planet Researchers say the measures the ancient humans took may have contributed to their spread throughout Europe and Asia when the Neanderthal population was declining and eventually disappeared around 40,000 years ago. 'In the study, we combined all of the regions where the magnetic field would not have been connected, allowing cosmic radiation, or any kind of energetic particles from the sun, to seep all the way in to the ground,' lead researcher Agnit Mukhopadhyay said. 'We found that many of those regions actually match pretty closely with early human activity from 41,000 years ago, specifically an increase in the use of caves and an increase in the use of prehistoric sunscreen.' Researchers said their work highlighted that people were still able to survive on a planet whose atmosphere looked a lot different than ours today, and this has implications for the search for life on planets other than Earth. Copyright 2025 Nexstar Media, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.
Yahoo
16-04-2025
- Science
- Yahoo
Sunscreen may have kept ancient humans alive during a polar reversal
Despite the sunscreen misinformation you might see online, ancient humans did face problems from the sun's harmful rays. Ancient Homo sapiens about 40,000 years ago may have even benefited from some of the same technologies that we use to avoid sunburns today–mineral sunscreen, tailored clothes, and using caves for shade and shelter. These advances may have been particularly advantageous when Earth's magnetic poles switched a bit, according to a study published April 16 in the journal Science Advances. Earth's magnetic field is created by its rotation, as well as the rotation of our planet's core. The core, which is made up of molten iron, generates electrical currents. These currents extend a sort of halo around the globe that helps protect Earth from cosmic radiation. This radiation thins Earth's ozone layer and lets in more ultra violet (UV) and the interaction of these particles with the Earth's magnetic field also results in aurora. Currently, this magnetic field has a north and south orientation in the form of Earth's North and South poles. This is why you typically see auroras in regions close to the poles, where magnetic fields are the strongest. Occasionally, these poles wander from their traditional geographic positions. These are called geomagnetic excursions. This natural process has occurred roughly 180 times over our planet's 4.5 billion-year geological history. Scientists believe that it is caused by some instability in the processes that generate Earth's magnetic field. The most recent geomagnetic excursion is called the Laschamps excursion and occurred about 41 to 42,000 years ago, when the magnetic North Pole began to shift over Europe. During this reversal, the magnetic field weakened, causing aurora over most of the globe and allowed more harmful UV light to come in from space. [ Related: A geomagnetic curveball 42,000 years ago changed our planet forever. ] Around this same time, archeological evidence shows that Homo sapiens were likely making tailored clothing for themselves and using a pigment called ochre with greater frequency. Ochre itself has some sun-protective properties when applied to the skin and may have helped ancient humans spread throughout present-day Europe and Asia as the Neanderthal population was declining. 'In the study, we combined all of the regions where the magnetic field would not have been connected, allowing cosmic radiation, or any kind of energetic particles from the sun, to seep all the way in to the ground,' study co-author Agnit Mukhopadhyay, a space physicist at the University of Michigan, said in a statement. 'We found that many of those regions actually match pretty closely with early human activity from 41,000 years ago, specifically an increase in the use of caves and an increase in the use of prehistoric sunscreen.' The team built models of the interaction of space particles and Earth's magnetic field using the Space Weather Modeling Framework. Mukhopadhyay developed a model that predicts how this plasma system will interact with Earth's magnetic field–ultmately forming an aurora. Working with Sanja Panovska from Germany's GFZ Helmholtz Centre for Geosciences, Mukhopadhyay created a 3D reconstruction of Earth's geospace system. They combined three separate models: a global model that reconstructs the geomagnetic field during the Laschamps excursion, one model of the space plasma environment around Earth, and another model that predicted what Earth's aurora looked like at the time. The resulting 3D model showed where charged particles were able to slip through Earth's geomagnetic field. During the Laschamps excursion, Earth's magnetic field reduced in size to about 10 percent of its current strength. As a result, Earth's magnetic poles drooped down near the equator and the magnetic field lines expanded. This expansion meant the aurora could have been visible all over Europe and into northern Africa. When the team laid their 3D map of Earth's space system over the world, they found that the time period of the Laschamps excursion coincided with periods of change for groups of humans living on the planet Homo sapiens and Neanderthals coexisted in Europe beginning roughly 56,000 years ago. However, Neanderthals were no longer identified as a species in Europe by about 40,000 years ago. 'What some of the differences are between these species, between Neanderthals and anatomically modern humans, that might account for that disappearance has been a major anthropological question for decades,' study co-author and University of Michigan anthropologist Raven Garvey, said in a statement. Garvey suggests that clothing itself might have been a major difference between the species. The technological means of making clothing that fitted to the body have been discovered at archaeological sites associated with anatomically modern humans, but not necessarily sites where Neanderthals lived. Archaeologists have found scrapers used in hide production, as well as needles and awls needed for sewing at sites associated with anatomically modern humans. According to Garvey, tailored clothing like this was significantly warmer. This added warmth meant that people could travel farther to find food and provided protection from sun damage, she said. [ Related: Ice age humans made needles from animal bones, archeologists discover. ] Because there are multiple detrimental effects of solar radiation, including potentially increased infant mortality, 'having protection against solar radiation would also have conferred significant advantage to anyone who possessed it,' Garvey said. Additionally, ancient humans may have ramped up their use of ochre. This naturally occurring pigment is composed of iron oxide, clay, and silica and has been used by several species of hominins for thousands of years. People used it to paint objects, on cave walls and even to decorate their bodies. 'There have been some experimental tests that show it has sunscreen-like properties. It's a pretty effective sunscreen, and there are also ethnographic populations that have used it primarily for that purpose,' Garvey said. 'Its increased production and its association primarily with anatomically modern humans (during the Laschamps) is also suggestive of people's having used it for this purpose as well.' According to the team, while these findings are not definitive, they offer a new way to look at already existing data. 'I think it's important to note that these findings are correlational and (ours is a) meta analysis, if you will,' Garvey said. 'But I think it is a fresh perspective on these data in light of the Laschamps excursion.' The 3D model offers us a way to predict how future excursions might affect us. If a reversal like this were to occur today, we could see complete blackouts with communication satellites not working, telecommunications in disarray. These types of events have already happened, even during smaller space weather events. This work also highlights that humans were still able to survive on a planet whose atmosphere looked a lot different than ours does today. 'Many people say that a planet cannot sustain life without a strong magnetic field,' Mukhopadhyay said. 'Looking at prehistoric Earth, and especially at events like this, helps us study exoplanetary physics from a very different vantage point. Life did exist back then. But it was a little bit different than it is today.'
