STEVE INSKEEP, host:
We're going next into the heart of the rainforest and into the heart of the past. The Amazon has traditionally been described as a vast virgin jungle where people have barely left a mark. The only inhabitants were believed to be hunter-gatherers. The rainforest was considered too hostile to have supported big civilizations in the past.
But archaeologists are now saying that instead of being a historical black hole, the Amazon was once home to large, even advanced, civilizations when Europeans arrived hundreds of years ago. NPR's Juan Forero traveled into the Peruvian jungle to visit one newly discovered site.
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JUAN FORERO: The small engine on a dugout canoe finally catches. And moments later, Augusto Oyuela, an archaeologist from the University of Florida, is gliding into the jungle. There are monkeys, bright-colored birds, and a forest so thick it's hard to make headway - wild, as if it's been like this forever. Except that here, scientists say it wasn't.
Instead, says Oyuela, a thriving and advanced Indian civilization once ruled here. He says the proof is under his feet and all around: from poor soils that were enriched, to orchards of semi-domesticated fruit trees.
Dr. AUGUSTO OYUELA (Archaeologist, University of Florida): All this forest has been selected by the humans through hundreds of years of use.
FORERO: This scene, scientists say, is repeated over and over again across Amazonia. Using ground-penetrating radar and other technologies, archaeologists are increasingly excavating causeways, moats and other manmade works. That has prompted archaeologists like the Brazilian Eduardo Neves to rethink what the Amazon looked like before the Europeans arrived.
Dr. EDUARDO NEVES (Archaeologist): The idea that the Amazon represents a pristine forest, one of the last places in the world that has been untouched by human action, it's just falling apart.
FORERO: There are detractors, of course, who say the new theories are based more on wishful thinking than science. But these days, conferences assembling hundreds of archaeologists convene to discuss the new findings. And there are acclaimed books about the discoveries, like Charles Mann's "1491" and David Grann's "Lost City of Z."
The new thinking has given much more credence to the reports the Spanish explorers penned in the early 1500s. They had written about finding cities gleaming white. But because there were no majestic stone ruins - and later generations of explorers encountered primitive bands of hunters - science considered that Amazonia had pretty much always been the way it is today. Then came Anna Roosevelt and her excavations in the late 1980s at Marajo Island at the mouth of the Amazon.
Dr. ANNA ROOSEVELT (Archaeologist): They have magnitude. They have complexity. They are amazing, and they are not primitive.
FORERO: She spoke of the civilization she uncovered after finding elaborate pottery, house foundations and signs of extensive agriculture. Many others later followed deep into the jungle, including Augusto Oyuela, the University of Florida archaeologist.
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FORERO: Wearing gloves, netting and long sleeves to ward off mosquitoes, Oyuela pushes into the forest and explains the evidence. The biggest clue is perhaps the soil, which here - as elsewhere across Amazonia - was too poor to sustain a civilization. So the Indians simply altered it.
Dr. OYUELA: What you have here is a high content of charcoal, phosphorus and calcium.
FORERO: Adding those elements, Oyuela explains, created soil as nutrient-rich as the American Midwest. And then there are the trees.
Dr. OYUELA: This is a landscape that every tree, or most of the trees that you see today, has been selected by the history, by the use of the past.
FORERO: He means the semi-domesticated clusters of palms, descendants of fruit tree orchards managed by Indians centuries ago. Today, of course, the great civilization that Oyuela says thrived here is gone - the Omaguas that Spanish explorers said they'd encountered. But their descendants remain, including the man who led Oyuela to this spot, Daniel Saldana. He's now farming right here, on land enriched by his ancestors.
Juan Forero, NPR News.
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