The Amazon basin could potentially hold 10,000 to 24,000 undiscovered ancient earthworks, according to a paper published last Thursday, October 5 in the journal Science. Using light detection and ranging (LiDAR) technology over the course of a five-year aerial survey, researchers discovered 24 previously unidentified pre-colonial structures and modeled the occurrence across the densely forested region to reach the new estimate.
For over 12,000 years, the Amazon region spanning 2.59 million square miles has been home to a diverse variety of Indigenous communities. Prior to the Spanish invasion, Amazonian Indigenous groups often used different methods to manipulate the landscape for social and ritualistic purposes, as well as building defensive structures. Known as earthworks, these human-made land formations included circular ditches, ponds and wells, and geometric symbols etched into the ground. Historically, these earthworks have been identified with satellite imagery in deforested areas, but due to the Amazon’s thick canopy, many of these sites have been difficult to document, according to the paper.
“These archaeological legacies can play a role in present-day debates around Indigenous territorial rights,” the researchers said. “They serve as tangible proof of an ancestor’s occupation, way of life, and their relationship with the forest. Today, Indigenous peoples struggle to recognize their right to land originally inhabited by their ancestors, along with the protection of their territories, languages, cultures, and heritages.”
More than 10,000 Pre-Columbian archaeological sites likely rest undiscovered throughout the Amazon basin, estimates a new Science study.
Led by Vinicius Peripato and Luiz Aragão of Brazil’s National Institute for Space Research, researchers used remote-sensing LiDAR technology to identify and reproduce extremely detailed images of 24 newly discovered archaeological sites beneath the Amazon forest covering. These findings include a fortified village, an ancient plaza town, and several rectangular and circular geoglyphs used for ceremonial, domestic, hunting, and defensive purposes.
Researchers noted that previous finds indicated that forests abundant with ancient earthworks were more probable in areas with high temperatures but low precipitation, as “the presence of a drier season facilitates burning, which could help remove the vegetation for building earth structures.” These formations were also more likely to be found in regions where the soil had “better texture for earthmoving” with high clay and silt content.
But new LiDAR scans suggest “that pre-Columbian societies engaged in earthwork construction in all other regions, covering a broader area than previously thought,” researchers wrote.
Peripato told Hyperallergic that as more archaeological discoveries are made with remote LiDAR and other technological innovations, it is “key” for the archaeologic prospecting process to include the consent of Indigenous communities.
“Amazonia was home to dense and complex societies that managed to use the forest without destroying it,” Peripato said. “They altered the geography and biodiversity of the Amazon to sustain their lives, and faced with the need to keep the Amazon rainforest standing, as it affects regional and global climate patterns, understanding the management adopted by these pre-Columbian societies could greatly contribute to the development of the current bio-economy.”