Amazonian earthwork survey indicates ancient population was much larger than thought

TL;DR - Aerial laser scanning suggests that less than 3% of Greater Amazonia supported 1.25–3 million people and over 20,000 earthworks from AD 100–300. The findings challenge estimates of pre-colonial population density and imply lasting human influence on Amazonian ecosystems.

• The surveyed area represents under 3% of Greater Amazonia.
• Estimated population ranged from 1.25 million to 3 million.
• Researchers identified more than 20,000 human-made earthworks.
• The results could reshape understanding of present-day tropical soils and forests.