Unveiling the Hidden Wonders: Scientists Discover Ancient Earthworks: You Won't Believe How Many Exist!

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New research reveals that a staggering number of over 10,000 pre-Columbian earthworks, including two dozen recently unveiled in the depths of the Amazon rainforest, are yet to be uncovered.

University of Houston

A lost Maya city in the jungle has been uncovered through laser mapping. The vast rainforests of the Amazon basin conceal an extensive network of ancient human structures, such as ditches, paths, and wells, which form intricate geometric patterns. These earthworks were meticulously crafted by indigenous communities that thrived in the region between 500 and 1,500 years ago.

Earthworks have been historically associated with ceremonial and defensive purposes, providing valuable insights into the appearance of ancient settlements.

Deforested regions in the Amazon have revealed numerous earthworks predating the arrival of European colonizers. However, it is believed that many more of these sites remain hidden today, concealed by dense foliage. In order to locate them, scientists have utilized remote sensing through a technique known as light detection and ranging, or lidar. This aerial method involves emitting laser pulses towards the ground, which measure the variations in distance. The combination of this data with other information is then used to generate 3D maps of the underlying landscape.

Geographer Vinicius Peripato, a researcher at Brazil's National Institute for Space Research in São Paulo, emphasized the significance of lidar in verifying the existence of structures, particularly those hidden beneath the forest. Peripato, lead author of a study published on October 5 in the journal Science, documented these discoveries.

In addition, the study authors examined tree species data from the Amazon spanning several decades, aiming to identify signs of species that were cultivated and domesticated by pre-Columbian civilizations. This extensive study involved the collaboration of 160 researchers and utilized data collected over an 80-year period. By combining lidar technology with records of the distribution of trees in the Amazon, predictive models were employed to estimate the potential locations of undiscovered earthworks.

The work highlights that the Amazon is not a pristine wilderness but contributes to an emerging consensus that it has a rich and dynamic Indigenous history, according to Dr. Michael Heckenberger, a professor of anthropology at the University of Florida. Dr. Heckenberger, who has conducted research in the Brazilian Amazon since the 1990s, specifically in the Xingu region with indigenous peoples, was not involved in the study.

"The results come as no surprise, aligning with a prevailing pattern observed in studies on the Amazon region, which suggest a continuous escalation in the scope, intensity, and repercussions of human settlements within the Amazon forest," Heckenberger conveyed to CNN via email. He further emphasized that these findings serve to highlight the exceptionally vibrant and inventive cultural legacy exhibited by indigenous communities both in the Americas and other regions worldwide.

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Displayed are the lidar data outputs that are used to study the earthworks hidden beneath the dense canopy of the Amazon rainforest. At the top is the lidar point cloud, where the colors represent the varying heights. This is followed by the representation of the terrain slope, the hillshade rendering which simulates the sunlight's impact to enhance the visibility of the topography, and finally the elevation measurements of a cluster of earthworks.

The authors initially had doubts about the utility of the lidar data for their project, Peripato informed CNN. The scans were primarily intended for rainforest biomass estimation, resulting in lower resolution compared to standard archaeological surveys.

"We had initial uncertainties regarding potential findings," Peripato stated. "Thankfully, it turned out to be a fortunate gamble."

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Beneath the canopy

Examining the lidar data unveiled 24 earthworks that were previously unknown, spread out across various locations in the Amazon basin. These findings encompassed a town with a plaza and a fortified village in the southern region, megalithic structures in the north, and geoglyphs in the southwest, consisting of both rectangular and circular shapes.

Considering that the lidar coverage only accounted for a mere 0.08% of the vast Amazon rainforest, which spans approximately 2.6 million square miles (6.7 million square kilometers), Peripato explained that it is impractical to conduct lidar scans across the entire region.

In order to obtain more precise estimates of the number of undiscovered earthworks, the computer model used by the teams required a significant amount of additional data. Therefore, the scientists utilized mapping techniques to document a total of 937 previously identified earthworks. They then directed the model to identify potential earthworks based on their shared topographic characteristics with these known sites.

To further refine their search, the researchers analyzed tree survey data from 1,676 forest plots. Their objective was to identify any indications of the presence of the 79 plant species that were known to have been cultivated and domesticated by pre-Columbian cultures.

The estimated model indicates that there could be over 10,000 and potentially more than 23,000 hidden earthworks beneath the dense foliage of the Amazon rainforest. This discovery implies that the identified locations account for less than 9% of the potential archaeological sites that could be preserved under the cover of the rainforest.

New research confirms age of ancient footprints

National Park Service

Scientists have verified evidence that humans reached the Americas much earlier than previously believed. What sets this study apart is the active involvement of multiple Brazilian experts, which is a rarity in Amazon-related projects. Dr. Juan Carlos Fernandez Diaz, a research assistant professor at the University of Houston, highlighted the importance of celebrating and supporting the participation of local scientists, stating that it deserves recognition from the media and the wider academic community.

Furthermore, according to Heckenberger, the authors appropriately emphasize the significance of Indigenous knowledge, appreciate a sense of local pride, and advocate for territorial rights.

Peripato stated that these discoveries may inspire fresh archaeological expeditions in previously unexplored regions of the Amazon, expanding into a more extensive area spanning throughout Amazonia. This potential confirmation of numerous pre-Columbian earthworks could also impact ongoing political discussions in Brazil concerning land rights. By validating the historical existence of indigenous communities in disputed areas and strengthening their descendants' claims to ancestral lands, these findings hold significant importance.

Mindy Weisberger is a science writer and media producer whose work has appeared in Live Science, Scientific American and How It Works magazine.