LiDAR Survey Reveals Forgotten Aquiry Civilization May Have Housed Up to 3 Million People in Amazonia

Airborne laser scans of southwestern Amazonia have revealed a landscape of geometric earthworks, straight roads and large ceremonial centers built by the Aquiry civilization, a multicultural society that occupied about 183,000 square kilometers between 600 BCE and 850 CE, according to a study published in the journal Nature. Researchers led by Martti Pärssinen, emeritus professor at the University of Helsinki, documented more than 400 well-preserved examples of monumental earthen architecture in a representative portion of that territory and, projecting the results across the civilization's full range, estimated more than 20,000 ancient ceremonial centers, the largest spanning 50 hectares.

Archaeological surveys and radiocarbon dating indicate that between 1.25 million and 3 million people lived in Aquirian territory by the start of the first millennium, an area representing less than 3% of Greater Amazonia. That estimate alone challenges earlier calculations that placed the entire Amazon's population between 1 million and 10 million people. "Our findings overturn our understanding of the Amazon region's past," Pärssinen said.

The Aquiry burned bamboo-dominated areas to create fields for maize, squash and manioc and to clear space for ceremonial centers and connecting roads, while cultivating gardens and managing useful tree species such as Brazil nut trees and peach palms. "The research shows that the human impact on the Amazon's environment has been far greater than previously believed," Pärssinen said.

The survey used LiDAR, airborne laser scanning that maps the shape of land beneath thick vegetation, flying roughly 450-kilometer transects that mapped a one-kilometer-wide strip every ten kilometers across about 4,500 square kilometers. Researchers used more than half of that scanned area for their systematic assessment. Because suitable stone is scarce in the region, the Aquiry left no stone ruins; their monumental earthworks, known as Amazonian geoglyphs, are the surviving evidence of the civilization, whose apparent collapse around 850 CE remains unexplained.