Southern California Mass Extinctions Were Caused by Fire

Fire changed everything:

Yet even modest numbers of humans literally burned their way into history. As soon as humans arrive on the scene, “suddenly, there’s tons of fire in the record,” Lindsey said.

These massive fires changed everything, the researchers argue. While their sources of ignition were quite different from the power lines and exhaust pipes that tend to spark fires today, our Pleistocene ancestors had few tools at their disposal to extinguish a blaze once it spread out of control.

Once-abundant junipers and oaks could tolerate drought, but had no defenses against fire. They disappeared, and fire-adapted pines and chaparral took their place. In a landscape stripped of shade, shelter and hiding places, food chains were upended. Intense fire may have altered water flows or cut off migration routes.

According to the fossil record, all of this devastation took barely 200 years. 

“This is the most significant extinction since a meteor slammed into Earth and wiped out all the big dinosaurs. It’s probably the first pulse of the extinction crisis that we’re in today,” Lindsey said.