A sprawling lost civilization, potentially home to millions of people, has been uncovered beneath the Amazon rainforest, according to new research. Scientists used airborne laser scanning technology, known as LiDAR, to peer through the dense canopy and reveal a network of approximately 20,000 earthworks, including ceremonial structures and roads.
The findings suggest that the ancient Aquiry civilization, which occupied an area comparable to the size of the United Kingdom in what is now the Brazilian state of Acre, flourished during the first millennium AD. Researchers estimate that between 1.25 million and three million people lived in the region at the start of the first millennium, a figure that overturns long-held beliefs about the Amazon's low population density prior to European contact.
LiDAR technology, which fires laser pulses through gaps in the forest canopy, allowed researchers to map the ground beneath and identify hundreds of previously unknown earthworks. These structures, created by digging ditches and piling excavated earth into raised embankments, form geometric shapes such as circles, squares, rectangles, and octagons, with some measuring hundreds of meters across.
These earthworks appear to have served as ceremonial and political centers where communities gathered for rituals, trade, feasting, and decision-making. Native oral traditions suggest these centers were built to foster relations among different communities. The largest sites were interconnected by remarkably straight roads and causeways, indicating a planned regional network rather than isolated settlements.
The Aquiry people transformed the landscape on a large scale, cultivating crops like maize, cassava, and squash, practicing horticulture, and managing valuable tree species. This contradicts the traditional view of the Amazon as an untouched wilderness before European arrival. The Aquiry are believed to have cleared some forest for ceremonial centers and agricultural fields.
Professor Martti Pärssinen, lead author of the study from the University of Helsinki, stated that the findings could transform understanding of how ancient peoples lived in the challenging Amazonian environment. The research shows that human impact on the Amazon's environment has been far greater than previously thought, with implications for understanding the region's biocultural history.
It is currently unknown what languages were spoken by the Aquiry people or what they called themselves. The cause of their apparent rapid collapse around 850 AD also remains unclear.
Researchers emphasize that only a small portion of the Amazon has been surveyed with LiDAR, suggesting that thousands more ancient settlements and earthworks may still lie hidden beneath the jungle. The study, published in the journal Nature, highlights that this single cultural area contains as many earthworks as previously estimated for the entire Amazon basin. If similar discoveries are made elsewhere, precolonial population densities and their effects on the Amazon's soil, forest structure, biodiversity, and even global climate models may need re-evaluation.