Here is a new excellent article
http://news.mongabay.com/2006/0514-amazon.html
Amazon Stonehenge suggests advanced ancient rainforest culture
By Rhett Butler, mongabay.com
May 14, 2006 (modified from an earlier article)
The discovery of an ancient astrological observatory in Brazil lends support to the theory that the Amazon rainforest was once home to advanced cultures and large sedentary populations of people. Besides the well-known empires of the Inca and their predecessors, millions of people once lived in the forests and shaped the environment to suit their own needs.
Because the Amazon's most skilled agriculturalists were killed off by European diseases, much of what was known about cultivating the rainforest ecosystem has been lost. Undoubtedly, these forest farmers relied on a far different agricultural philosophy than that used today -- one, says Clark Erickson from the University of Pennsylvania, that sustained significant populations without destroying biodiversity. Their techniques, if uncovered, could prove useful and possibly essential in creating areas of high agricultural productivity without utter destruction. Instead of clearing large areas for crops with small yields and short life-spans and pastureland for low-density cattle grazing, perhaps the employment of ancient and apparently profoundly effective methods could revolutionize modern cultivation with minimal environmental impact.
