Lidar Reveals 20,000+ Ancient Earthworks in the Amazon, Upending Long-Held Assumptions About Precolonial Settlement

A July 29, 2026 Nature study used lidar to identify over 20,000 precolonial geoglyphs across the southwest Amazon, near the Brazil-Bolivia border region. The find directly challenges the decades-old view that the Amazon's nutrient-poor soils could not support dense, sedentary populations capable of monumental earthwork construction. The scale implies organized societies far larger than earlier models allowed.