Laser scanning reveals vast lost civilization in the Amazon

Large-scale aerial laser scanning has revealed that an ancient civilization in the southwestern part of the Amazon was far larger than scientists had previously assumed. According to the study, it left behind tens of thousands of monumental earthworks, and its population during its peak could have reached up to 3 million people.

The results, published Wednesday in the journal "Nature," describe the Aquirí civilization - a network of communities that flourished roughly from 600 BC to 850 AD across an area of about 183,000 square kilometers, which today falls within the Brazilian states of Acre and Amazonas.

Hidden beneath the jungle canopy

In 2024, a team led by Martti Pärssinen, professor emeritus at the University of Helsinki, flew over nearly 4,500 square kilometers of tropical forest using LiDAR - a technology that sends laser pulses from an aircraft to map the terrain under dense vegetation. This survey discovered 432 geometric earthworks, of which 396 were previously unknown to science.

By extrapolating these data across the entire Aquirí territory, scientists conclude that the civilization likely possessed between 24,000 and 30,000 such structures. Some of the earthen constructions reach up to 50 hectares, and the ditches are typically about 12 meters wide and up to 5 meters deep.

"The scale and precision of these constructions are simply staggering," Pärssinen told "New Scientist".

Population in the millions

Using estimates for the labor required for construction and settlement density, researchers calculate that in the period between 100 and 300 AD, the population at its peak reached from 1.25 to 3 million people - and that on a territory occupying less than 3% of the so-called Greater Amazonia. This discovery challenges previous, more conservative estimates for the entire Amazon basin, which suggested that between 1 and 10 million people lived there, and suggests that the total population of the region may have been in the tens of millions.

Michael Heckenberger of the University of Florida describes these demographic estimates as "plausible and extremely important, even staggering".

Rewriting the history of the Amazon

The Aquirí were not a single kingdom, but a branched network of communities that built ceremonial centers connected by wide roads. Archaeological data show that they burned bamboo forests to grow maize, squash, and manioc, and also cultivated fruit-bearing trees, including Brazil nut and peach palm, thereby transforming the ecosystem over the course of centuries.

"The idea of the Amazon as an untouched wilderness is largely a myth," says Pärssinen. The reasons for the rapid decline of this civilization around 850 AD, however, still remain unclear.