Satellite images of the upper Amazon Basin in Brazil taken since 1999 have revealed hundreds of circles, squares, and other geometric shapes once hidden by the Amazon rain forests. They hint at a previously unknown ancient society that flourished in the Amazon. Now researchers estimate that nearly ten times as many such structures, of unknown purpose, may exist undetected under the Amazon forest cover. The discovery adds to evidence that the hinterlands of the Amazon once teemed with complex societies, which were largely wiped out by diseases brought to South America by European colonists in the 15th and 16th centuries. Since these vanished societies had gone unrecorded, earlier research had suggested that soils in the upper Amazon were too poor to support the extensive agriculture needed for such large, permanent settlements. The researchers say “We found that this view is wrong, and there is a lot more to discover in these places”.