March 28 (UPI) -- Archaeologists have discovered manmade earthworks in the remote rainforest of Brazil, a region thought uninhabited by humans.
Researchers thought early human populations in South America lived only near major waterways, but the latest discovery suggests early Amazonian communities occupied the most remote portions of the rainforest.
Vast swaths of the Amazonian rainforest remains unexplored by archaeologists. The latest finds suggest more communities are out there waiting to be discovered.
Researchers surveyed a patch of rainforest encompassing 155,000 square miles and found 81 geoglyphs, manmade mounds and ditches. Scientists estimate more than 1,300 geoglyphs are scattered across Southern Amazonia.
The findings, published this week in the journal Nature Communications, offer further proof that humans have been shaping the geography of the Amazon for thousands of years.
"There is a common misconception that the Amazon is an untouched landscape, home to scattered, nomadic communities," Jonas Gregorio de Souza, an archaeologist at the University of Exeter, said in a news release. "This is not the case. We have found that some populations away from the major rivers are much larger than previously thought, and these people had an impact on the environment which we can still find today."
"The Amazon is crucial to regulating the Earth's climate, and knowing more about its history will help everyone make informed decisions about how it should be cared for in the future," de Souza said.
Researchers believe the square and circular-shaped ditches built by early Amazonian populations likely served the purpose of irrigation, allowing people to clear the forest for growing crops without sacrificing access to water.
As new surveys are conducted in previously unexplored portions of the Amazon, scientists expect to find more evidence of ancient communities.
"We are gradually piecing together more and more information about the history of the largest rainforest on the planet," Exeter professor José Iriarte said. "Our research shows we need to re-evaluate the history of the Amazon. It certainly wasn't an area populated only near the banks of large rivers, and the people who lived there did change the landscape. The area we surveyed had a population of at least tens of thousands."