An unusual scientific collaboration, bringing together archaeology and geophysics, is exploring how "weird space weather" may have influenced human behavior on Earth approximately 41,000 years ago. This period coincides with a significant geomagnetic event known as the Laschamps Excursion, during which Earth's magnetic field experienced a near-collapse.
What happened during the Laschamps Excursion?
Around 41,000 years ago, Earth's magnetic field weakened dramatically, dropping to less than 10% of its modern intensity. Instead of its usual stable, bar-magnet-like configuration (a dipole), the field fractured into multiple weak poles that wandered erratically. This caused the Earth's protective magnetosphere to become distorted and "leaky."
How could this "space weather" have influenced human behavior?
The weakened magnetic field had several profound effects on Earth's environment:
Increased Radiation: More harmful solar radiation and cosmic rays were able to penetrate Earth's atmosphere, leading to elevated risks of sunburn, eye damage, and potentially other health issues for humans.
Widespread Auroras: Auroras, typically confined to polar regions, would have been visible much closer to the equator, potentially inspiring awe, fear, or influencing ritualistic behaviors in ancient populations.
Atmospheric Changes: The influx of high-energy particles would have altered atmospheric chemistry and dynamics, including the destruction of stratospheric ozone, further increasing UV exposure.
Evidence of human behavioral adaptations:
The interdisciplinary team investigated archaeological records from this period, particularly in Europe where the effects of the Laschamps Excursion were pronounced. They found evidence suggesting several adaptive behaviors in early humans (Homo sapiens):
Increased Cave Habitation: Caves, offering natural shielding from UV rays, likely became more frequent shelters.
Tailored Clothing: There appears to be an increase in the production and use of tailored clothing, which could have provided better coverage and protection from solar radiation.
Ochre Use: Extensive use of ochre, a mineral pigment, is observed. It's hypothesized that ochre, which blocks UV light, may have been used as an early form of sunscreen.
While the study does not claim that space weather alone caused these behavioral shifts or, for instance, the extinction of Neanderthals (who coexisted with Homo sapiens at the time), it suggests that it could have been a contributing factor – an "invisible but powerful force" influencing innovation and adaptability.
The Significance of this Collaboration:
This collaboration between archaeologists and geophysicists is unusual but highly insightful. Geophysicists typically work with large datasets and models, while archaeology adds a human dimension to the science. By combining these disciplines, researchers can explore how planetary-scale geomagnetic instability might ripple down into the lived experiences of people on the ground, affecting how they adapt, create, and survive. Understanding how ancient humans responded to such events can offer valuable insights into how future space weather events might impact our technologically dependent world.