Ancient man-made structures found deep in the Amazon rain forest might have indicated human inhabitants that cleared the land thousands of years ago, but recent research suggests something different.

Instead of clearing the dense forest to make way for the circular earthwork structures, researchers at the University of Reading in the United Kingdom found evidence that the structures might actually predate the rain forest itself, which then later grew around them.

It was initially thought these structures in the Amazon in South America were made by farmers clearing the rainforest land, but more recent research revealed they were made in an area where dense vegetation likely never existed. (Image source: University of Reading)

It was initially thought these structures in the Amazon in South America were made by farmers clearing the rain forest land, but more recent research revealed they were made in an area where dense vegetation likely never existed. (Image source: University of Reading)

“These results were very surprising. We went to Bolivia hoping to find evidence of the kinds of crops being grown by ancient Amerindian groups, and to try to find how much impact they had on the ancient forest. What we found was that they were having virtually no effect on the forest, in terms of past deforestation, because it didn’t exist there until much later,” Dr. John Carson, a paleoecologist and lead author of the study, said.

The researchers analyzed sediment samples from the structures, finding pollen and other particles in the mud that helped indicate how the area’s ecosystem changed within the last 6,000 years. Instead of having to clear the land, the samples indicated the land was naturally clear for farmers’ use 2,500 to 500 years ago.

“Rather than cutting or burning down huge swathes of jungle, the early Amazonian people simply took advantage of a naturally more open landscape,” Carson said. “Still, the scale of the earthworks that where built on these sites suggests that the land was capable of supporting relatively large populations. Our analysis shows that they were growing maize and other food crops. They also likely caught fish, and there’s evidence from other parts of the Bolivian Amazon for people farming Muscovy ducks and Amazonian river turtles.

“Our findings have serious implications for understanding past climate change, and how the Amazon basin might react to more modern forest clearance,” he continued. “It suggests that Amazonia was neither pristine wilderness, nor has it shown resilience to large-scale deforestation by humans in the past.”

This research was published in the journal PLOS One this week.

(H/T: Huffington Post)