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Using advanced airborne laser scanning technology to peer beneath the dense canopy of the Amazon rainforest, archaeologists discovered 396 new ancient earthworks built by the Aquiry, a complex society that arose 2,500 years ago in Brazil, according to a study published July in the journal Nature.
Archaeological investigations in the Amazon have long been hindered by dense tree canopies. However, recent deployments of lidar technology across a 1,740-square-mile (4,500-square-kilometer) area in Brazil’s Acre state have unveiled monumental geometric earthworks known as Amazonian geoglyphs. These structures, characterized by deep ditches and high outer embankments, reveal new insights into precolonial urban development and regional demographics.
Unveiling the Aquiry Civilization via Lidar Technology
Martti Pärssinen, an archaeologist at the University of Helsinki who has investigated geometric earthworks in Brazil for over two decades, led the research team behind the latest survey. In a 2021 study, Pärssinen officially introduced the name Aquiry for this multicultural ancient civilization, named after the Acre River. The term Aquiry translates to “river of caimans” in the language spoken by the Indigenous Arawakan people.
Between 600 B.C. and A.D. 850, the Aquiry constructed these monumental geometric forms, which served multiple societal functions. According to native oral traditions documented by the researchers, the centers were built to foster relations among communities and with significant otherworldly beings. They also functioned as venues for communal gatherings, political decision-making, and ceremonial displays by local chiefs. Residents lived in multifamily longhouses surrounding the earthworks, cultivating crops such as maize and squash.
In Plain English: The Clinical Takeaway
- Remote Sensing: Airborne laser scanning (lidar) uses light pulses to map ground contours through dense vegetation without disturbing topsoil or ecosystems.
- Demographic Estimation: Population figures are calculated using structural metrics, such as the estimated human labor required to build and maintain large-scale earthworks.
Demographic Scale and the Mystery of the Collapse
To date, archaeologists have identified approximately 1,700 geoglyphs in the region. Based on extrapolation, researchers estimate that more than 20,000 Aquiry earthworks remain undiscovered in unsurveyed zones. Factoring in an average estimate of 300 individuals required to construct and maintain each geoglyph, the study suggests the civilization peaked at a population between 1.25 million and 3 million people from A.D. 100 to 300.
Despite their vast scale and organizational complexity, the society experienced a sudden shift. “We do not know why the geoglyphs were suddenly abandoned between A.D. 850 and 950,” Pärssinen stated. The available evidence points to a relatively rapid collapse, aligning chronologically with the disappearance of other major precolonial powers, including the Classic Maya in Central America and the Tiwanaku and Wari civilizations in the Andes.
| Civilization | Geographical Location | Active Construction Period | Primary Architectural Motifs |
|---|---|---|---|
| Aquiry | Southwest Amazon (Brazil) | 600 B.C. – A.D. 850 | Geometric forms, deep ditches, embankments |
| Nazca | Southern Peru | 200 B.C. – A.D. 500 | Animals, humans, plants, straight lines |
Geographical Contrast with the Nazca Lines
Similar geoglyphs, dating between 200 B.C. and A.D. 500, exist in Peru. Known as the Nazca Lines, these earthworks feature motifs shaped like animals, humans, plants, and fantastical figures alongside geometric designs. The Nazca were an interconnected regional society of precolonial farmers situated roughly 1,050 miles (1,700 kilometers) from the Aquiry territory.
“The Nazca geoglyphs represent a different phenomenon and were probably unrelated to the Aquiry civilization,” Pärssinen noted. “Nevertheless, in both cases, the straight roads and lines, as well as the geometric forms and motifs, are best appreciated from the air.” The proliferation of thousands of geoglyphs across the southwest Amazon forces researchers to reevaluate longstanding assumptions regarding precolonial urban planning and population distribution in tropical forest environments.
References
- Pärssinen, M., et al. (2026). Amazonian geoglyphs and the demographic scale of the ancient Aquiry civilization. Nature.
