But Brazil’s National Institute of Space Research (INPE) has only been keeping fire records since 1998, and two decades isn’t long in the life of a forest where trees live for centuries and humans have been setting fires for millennia.

Paleoecology—the study of ancient environments—offers unique insights into how the first Amazonian peoples manipulated fire in the landscape, the effects of those fires on the forest’s ecology over time, and lessons that might help to prevent modern fires.

Layers of charcoal buried below the rainforest’s surface reveal that for thousands of years, the Amazon’s ancient inhabitants used fire to clear the forest floor for agriculture—and that it had a lasting effect, making those areas more fire prone today. But unlike many