41,000 years ago, Earth's magnetic field weakened dramatically. This period, known as the Laschamps excursion, may have unexpectedly influenced life on Earth. A collaboration between archaeologists and geophysicists is exploring these little-known connections.
During the Laschamps excursion, Earth's magnetic poles wandered erratically, and the field's intensity dropped to less than 10% of its current value.
Unlike a magnetic reversal, where the north and south poles switch places, the poles simply wandered unpredictably during this period. This disruption caused the magnetic field to fragment into several weak poles, reducing the protection offered by the magnetosphere against solar radiation.
This situation left the magnetosphere, our shield against solar radiation, particularly vulnerable. The consequences for life on Earth may have been numerous, from auroras visible near the equator to increased ultraviolet radiation reaching the surface.
Human populations at the time, including Neanderthals and Homo sapiens, may have had to adapt to these environmental changes. The increased use of pigments like ochre for sun protection or the search for deeper shelters could be direct responses to these conditions. These adaptations are visible in the archaeological record and testify to human resilience.
This interdisciplinary study highlights the importance of considering space phenomena in the study of human evolution. Geophysicists provide an understanding of cosmic mechanisms, while archaeologists offer tangible evidence of their impacts on ancient societies. Together, they open new perspectives on the interaction between humans and their environment.
Events like the Laschamps excursion are not unique in Earth's history. Understanding how our ancestors coped can help us anticipate the future effects of variations in Earth's magnetic field.