Although human sacrifices may have coincided with extreme weather events, violence was the norm in northern Peru. Credit: VW Pics via Getty Images

Today’s cataclysmic climate change-fueled disasters are scary enough even when we understand the root causes. Prehistoric cultures unfortunately didn’t have this luxury, and often responded dramatically to such changes. In northern Peru, archaeological evidence indicates local societies sometimes even turned to mass human sacrifices in an attempt to stop destructive flooding from events like El Niño.

That said, researchers are now confident these periods of intense violence weren’t the norm—nor were they necessarily linked to climate issues.…