Editor's summary of original article published in Science:

When intact, the Amazonian forest is dense and difficult to penetrate, both on foot and with scanning technologies. Over the past several years, however, improved light detection and ranging scans have begun to penetrate the forest canopy, revealing previously unknown evidence of past Amazonian cultures. Rostain et al. describe evidence of such an agrarian Amazonian culture that began more than 2000 years ago. They describe more than 6000 earthen platforms distributed in a geometic pattern connected by roads and intertwined with agricultural landscapes and river drainages in the Upano Valley. Previous efforts have described mounds and large monuments in Amazonia, but the complexity and extent of this development far surpasses these previous sites. —Sacha Vignieri