Wildfires Caused Mass Extinction After the Ice Age in Southern California

Ice Age mega firePhoto byCullen Townsend, Natural History Museum

Ice-age humans may have set megafires in Southern California, rendering the region uninhabitable for a millennium, according to groundbreaking research published in the journal Science.

Fossil evidence from the La Brea tar pits suggests that these massive wildfires could have been a significant factor in the extinction of the fauna in the area.

Lead author F. Robin O'Keefe, a biologist from Marshall University, compared the impact of these ancient fires to a bomb explosion.

When fires like this happen, it's almost like a bomb has gone off. It was like a wasteland for 1,000 years- F. Robin O'Keefe, Biologist, Marshall University

The study utilized a comprehensive dataset to model the evolving ecosystem of California following the retreat of North American glaciers during the late Ice Age. Crucial to the analysis was the carbon dating of fossils found in the La Brea tar pits, providing a unique record of the region's prehistoric fauna.

The research focused on eight common mammals, including saber-toothed cats and ancient bison, dating their remains to 15,600 and 10,000 years ago.

By comparing these fossils with pollen deposits and charcoal layers from wildfires in nearby Lake Elsinore, the researchers found a strong correlation between the rise in human settlements and the increased frequency of wildfires.

Around 13,500 years ago, charcoal deposits spiked, indicating a prolonged period of fires. While the exact cause remains uncertain—whether humans used fire for hunting or accidentally ignited it. But the fires might have made the region inhospitable for humans and wildlife.

All analyzed species, except coyotes, disappeared from the region 12,900 years ago, likely due to a combination of factors.

A changing climate, drought, and the transition of Southern California from a moist woodland to a dry shrubland set the stage for fires. Human populations grew, their fires reshaping the ecosystem, making it difficult for large animals to find food while humans hunted them.

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