Aerial Survey Uncovers Hundreds of New Ancient Earthworks in the Amazon

A remote-sensing flight over a 4,497-square-kilometre tract in Brazil near the Bolivia and Peru borders revealed 396 previously undocumented earthworks, prompting researchers to estimate that the Southwest Amazon may contain 24,000 to 30,000 such structures. The predominant form—large, geometric geoglyphs—are characteristic of the Aquiry civilization that existed between 600 BCE and 850 CE. Martti Pärssinen, emeritus professor at the University of Helsinki and lead author, suggests the civilization could have reached a peak population of three million people and occupied an area roughly the size of North Dakota.

Published in the journal Nature, the study argues that these numbers may require a major revision of pre-colonial Amazon demographics, potentially indicating tens of millions of inhabitants across the basin. Heiko Prümers of the German Archaeological Institute, while not involved in the research, cautions that site counts may be inflated by counting relocations or aggregating nearby features. The work also highlights that ancient peoples managed the forest sustainably, offering possible lessons for contemporary Amazon stewardship amid ongoing deforestation.