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Over 20,000 precolonial earthworks in the Southwest Amazonia
Martti Pärssinen1,2, Risto Kalliola3, Alceu Ranzi4
1Instituto Iberoamericano de Finlandia, Madrid, Spain. martti.parssinen@helsinki.fi.
Nature
|July 29, 2026
Summary
Ancient Amazonian earthworks reveal a vast, monument-building civilization. LiDAR technology uncovered more structures in one area than previously estimated for the entire region, suggesting a much larger population.
Area of Science:
- Archaeology
- Remote Sensing
- Amazonian Studies
Background:
- Southwestern Amazonia features numerous geometric earthworks, indicating a precolonial monument-building civilization.
- Previous studies were limited to deforested areas, hindering accurate estimates of civilization's extent and population.
- Understanding this civilization is crucial for discussions on Amazonia's deep history, urbanism, and environmental legacy.
Purpose of the Study:
- To better define the geographical distribution and quantity of earthworks in southwestern Amazonia.
- To improve estimates of the region's precolonial population size and density.
- To reassess the environmental impact of precolonial Amazonian populations.
Main Methods:
- Utilized canopy-penetrating LiDAR data covering 4,430 km².
- Integrated LiDAR data with existing archaeological records.
- Analyzed earthwork distribution and density.
Main Results:
- Identified a significant number of earthworks, comparable to previous estimates for all of Amazonia.
- Proposed a precolonial population estimate of 1.25-3 million people for the area between 100-300 AD.
- Demonstrated the effectiveness of LiDAR in detecting earthworks hidden by forest canopy.
Conclusions:
- The cultural area studied contains a substantial number of earthworks, significantly revising previous regional estimates.
- Precolonial Amazonian populations may have been much larger than previously thought.
- Re-evaluation of Amazonian soil, forest structure, biodiversity, and climate models is warranted given the revised population estimates.
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