Agnit Mukhopadhyay’s efforts to create the first 3D magnetic map of the Earth-space environment has suggested that caves, clothes and ochre-based sunscreens may have helped Homo sapiens survive increased solar radiation during a geomagnetic upheaval 41,000 years ago.
A study by Mukhopadhyay and his colleagues in institutions in the US and Europe has bolstered support for the idea that these behaviours may have protected modern humans from increased radiation triggered by a shift in the Earth’s magnetic field.
The Earth’s magnetic field had then dropped to 10 per cent of its current strength and the magnetic poles tilted towards the equator, the changes generating auroras across the world and allowing solar particles and radiation to penetrate the atmosphere.
Mukhopadhyay, originally from Calcutta and affiliated with the University of Michigan in the US, collaborating with Sanja Panovska at the Helmholtz Centre for Geosciences in Germany, created a 3D reconstruction of the Earth’s magnetic field during that period. The map revealed specific regions where high levels of solar particles and radiation would have reached the ground.
“We then compared these regions with archaeological records and found significant overlap between our auroral maps and zones marked by early human use of caves, emergence of tailored clothing, and ochre mines,” Mukhopadhyay told The Telegraph via email.
This correlation supports the hypothesis that Homo sapiens may have responded to these environmental pressures with adaptive behaviours, he said.
In contrast, the Neanderthals, an extinct human species that coexisted with Homo sapiens for tens of thousands of years, even exchanging genes, appear to have lacked these technologies and disappeared some 40,000 years ago.
For decades, a major question has been what differences between the Neanderthals and Homo sapiens might explain the Neanderthals’ disappearance, said Raven Garvey, a study team member and professor of anthropology at the University of Michigan.
At some sites associated with Homo sapiens, archaeologists have found not only stone scrapers used to turn hides into clothes but also needles and awls associated with sewing.
The researchers, whose study was published on Wednesday in the journal Science Advances, say other factors might also have contributed to the extinction of the Neanderthals and survival of Homo sapiens.
Tailored clothing has two-fold benefits, Garvey said in a media release from the university. It added warmth which meant people could travel further from the warmth of fires in their search for food. Tailored clothing could also have protected from sun damage, Garvey said.
The researchers say Homo sapiens may also have used the clay-like material called ochre that several species have used for painting cave walls and decorating their bodies. Archaeological evidence points to increased use of ochre by modern humans around 41,000 years ago.
Mukhopadhyay says the study also highlights that people were able to survive on a planet where the atmosphere looked a lot different than it is on Earth now. “Many people say a planet cannot sustain life without a strong magnetic field,” he said. “Looking at events like this on prehistoric Earth helps us study exoplanetary physics from a different vantage point.”