Brazil's northern Amazon region, once thought to have been pristine until the encroachment of modern development, actually hosted sophisticated networks of towns and villages hundreds of years ago, according to a new study by U.S. and Brazilian researchers.
A report by Dr Michael Heckenberger of the University of Florida and colleagues, published in today's issue of the journal Science, suggests the society was advanced and complex, and had worked out ways of using the Amazon forest without destroying it.
The researchers used archeological evidence and satellite images to show the area was densely settled long before Columbus and European settlers arrived, with towns featuring plazas, roads up to 50 m wide, deep moats and bridges.
Nineteen evenly spaced villages were linked by straight roads, and the cluster could have supported between 2,500 and 5,000 people, said the researchers. The villages were all laid out in a similar manner - and the roads were mathematically parallel: "This really blew us away," Heckenberger said. "It's fantastic stuff."
Heckenberger, who worked with indigenous chiefs from the Upper Xingu region as well as a team at the Universidade Federal do Rio de Janeiro, said the settlements dated to between 1200 A.D. and 1600 A.D.
"Every 3 km to 5 km there is another village or town," he said. "Some of these villages are 50 hectares in size ... maybe 150 or so acres in total size," he added.
"In the villages sometimes the roads are 50 m wide. Why 50 m? There were no wheeled vehicles. They were not having car races up and down these things and certainly you were not moving Incan armies."
Heckenberger believes the wide boulevards and plazas were the early Xinguano society's version of monuments - akin to the pyramids of the Maya: "Clearly it is an aesthetic thing," he said. "It speaks of very sophisticated astronomical knowledge and mathematical knowledge and the kind of things that we associate with pyramids. It is a different human alternative to social complexity."
It would have taken a productive economy to fund such works, he added. But the civilization was not as large and urbanised as better known South American civilizations.
"Everyone loves the 'lost civilization in the Amazon story'. What the Upper Xingu and middle Amazon stuff shows us is that Amazon people organised in an alternative way to urbanisation. We shouldn't be expecting to find lost cities. But that doesn't mean they were primitive tribes, either."
The agriculture was clearly sophisticated, too, the researchers said, and probably very unlike modern clear-cutting strategies. They clearly, however, altered the forest, Heckenberger said.
"What it does show is there are alternatives to what is commonly presented as an all-or-nothing scenario," he said.
The Amazon was not primordial when European colonists arrived - bringing with them the diseases such as smallpox and measles that virtually wiped out indigenous populations.
"I firmly believe that the majority of what is now forested landscape would have been converted into some other type of environment - secondary forest or fields of grass or orchards of fruit trees or manioc gardens," he said.
Xinguano people still live in the region and are certainly descended from whoever built the cities, he said - but the populations are considerably sparser.