An ancient Peruvian civilization may have been kick-started by a climate swing. Five thousand years ago, hunter-gatherers moved inland from the seashore, settling in arid, desolate river valleys where they learned to farm. Archaeologist Jonathan Haas thinks the new settlers were spurred to move by more frequent El Ninos, which killed the fish and shellfish they had relied on for food, reports NPR.
In those less hospitable dry valleys of Norte Chico, the settlers developed trade with their coastal neighbors and built huge terraced rock monuments and sunken circular plazas. "If you think about going from a hunter-gatherer society to this highly centralized society with an organized religion, it's a pretty dramatic change to take place over a very short period of time," says Haas.