Vast, geometric earthworks hidden beneath the Amazon rainforest canopy suggest that a complex civilization, potentially numbering in the millions, once thrived in the region, according to a study published in the journal Nature. This discovery challenges long-held assumptions about the Amazon as an untouched wilderness before the arrival of Europeans.
Using canopy-penetrating lidar technology, researchers surveyed over 1,700 square miles of dense rainforest. They uncovered more than 432 geoglyphs—large earthen formations created by excavating ditches and piling the excavated soil into embankments. These structures, which include circles, squares, rectangles, and octagons, were found connected by an intricate network of straight roads.
The findings focus on the Anquiry people, an Amazonian civilization that existed from approximately 600 BC to AD 850. Researchers estimate that the construction and maintenance of these earthworks would have required around 300 people, implying a total population of between 1.25 and 3 million people during the civilization's peak. Scientists speculate that as many as 30,000 such structures may exist across the Amazon basin.
Based on previous archaeological findings in Amazonian settlements, the researchers believe these geoglyphs served as ceremonial centers for gatherings, political decision-making, feasts, and performances. Family dwellings were likely situated around these community hubs. The intricate road systems indicate a well-organized society rather than isolated communities.
The Anquiry civilization significantly impacted the Amazonian landscape, clearing forests for agriculture to grow crops such as maize, squash, and manioc, as well as cultivating Brazil nuts and peach palms. While the reasons for their decline around 850 AD remain unclear, their existence demonstrates a substantial human footprint on the rainforest.
Lead author Martti Pärssinen of the University of Helsinki stated that these findings overturn the understanding of the Amazon's past and challenge the notion of it being an untouched wilderness. The researchers suggest that if similar discoveries are made elsewhere in the Amazon, the estimated precolonial population density and its impact on the rainforest's structure, biodiversity, and even global climate models may need re-evaluation. The study indicates that thousands more ancient settlements may still lie undiscovered within the rainforest.