The last remote and pristine forest on our distressed and overcrowded earth" is how Greenpeace describes the Amazon River Valley. For decades now, this romantic view of the Amazon, as a vestige of the once free land corrupted by the arrival of Europeans in the 15th century, has persisted in the popular imagination. Scientists also assumed, without evidence to the contrary, that indigenous tribes tiptoed their way through the forest, living their lives while leaving nature almost completely undisturbed. Human settlements and the grab for gold and timber, they thought, came to the world's largest rain forest only in the last few hundred years.
Now scientists are painting a radically different picture of the Amazon's prehistory. Long before Christopher Columbus dropped anchor in the New World, indigenous tribes were breaking ground on their version of Paris on the Amazon. They burned and chopped down swaths of rain forest to make way for majestic boulevards and circular plazas. They built networks of dikes, ponds and bridges and cleared acres of farmland to grow piqui, a palm fruit, and manioc, a cousin of the potato. Although they lived in mud and thatch huts and relied on their feet, not on animals or even carts, for transportation, their architectural vision rivaled that of the 19th-century Parisian planner, Baron Haussmann. "There was no pristine forest," says Michael Heckenberger, an archeologist at Florida State University in Gainesville and author of a study last week in the journal Science. "No part of it was untouched, unclaimed by human hands. What was there was left intentionally."
Heckenberger reached this conclusion after spending the past 12 years traveling with two Xinguano chiefs, whose names appear as coauthors, through the upper reaches of the Xingu, a sparsely settled tributary of the Amazon that flows through northeastern Brazil. They unearthed centuries of lost tribal history: dark, charcoal-rich earth and bits of ceramics marking the sites of old villages and mounds of soil testifying to ancient curbs, which the Xinguano used to mark the edges of their roads and the borders of villages. Heckenberger and his co-workers made a detailed map of a 583-square-kilometer swath of land that he believes was home to 19 villages and a population of 5,000 to 10,000 Xinguano--far more than previously thought. All told, the Amazon region is now believed to have supported a pre-Columbian population of 6.8 million, a far cry from earlier estimates of 250,000. Most died from epidemics of new diseases brought by the Europeans, such as smallpox; others were exported for slavery or killed for their land. Of the 19 prehistoric Xinguano villages, only three remain.
How did land that is so difficult to farm support so many people? The Xinguano and other tribes apparently practiced slash-and-burn agriculture. When they depleted the soil in one plot, they left it fallow and moved on to virgin forest or scrub. After 10 to 30 years, they would return to the original plots and farm them again.
Heckenberg's and other studies are greatly complicating the debate over land conservation. "There is this notion that there's a right way and a wrong way to do things, and that anything involving humans is the wrong way," says Clark Erickson, an archeologist at the University of Pennsylvania who is doing research on the Beni, a savannah region in the Bolivian Amazon. Some scientists, in fact, go so far as to claim that a degree of human intervention is actually beneficial to the environment because, in introducing new crops and enriching the soil, it increases biodiversity. Between the environmentalists, who want to fence off land as untouched wilderness, and the developers, who want to cut down trees and build roads, factories and towns, the new archeological evidence is creating a vast gray area. The Amazon, one of the largest, most biologically diverse regions of the world, is proving that it still has a few mysteries left.