New study reveals thousands of hidden pre-Columbian earthworks in the Amazon rainforest

In a groundbreaking study published in the journal Science, a global team of 230 researchers, hailing from 156 institutions across 24 countries and spanning four continents, led by Brazilian scholars Vinicius Peripato and Luiz Aragão, have revealed a surprising revelation about the Amazon rainforest. Utilizing cutting-edge remote sensing technology and advanced statistical modeling, the researchers estimate that hidden beneath the Amazon’s lush canopy lie more than 10,000 pre-Columbian earthworks, constructed before the arrival of Europeans.

This astonishing discovery was made possible through the use of LiDAR (Light Detection and Ranging) technology, a laser-mounted aircraft sensor that creates highly detailed 3D models of the forest’s surface. By digitally removing vegetation from these models, the team unearthed 24 previously unknown archaeological sites in various Brazilian states, including Mato Grosso, Acre, Amapá, Amazonas, and Pará.

These ancient earthworks, dating back 1,500 to 500 years, are a testament to the significant human occupation of the Amazon rainforest long before European contact. Moreover, the researchers found that these earthworks often go hand in hand with other landscape modifications, offering further evidence of Indigenous presence in different Amazonian regions.

In the words of Vinicius Peripato, “Our study challenges the conventional view of the Amazon rainforest as pristine, revealing a wealth of hidden history and human activity. As we delve deeper into understanding the extent of pre-Columbian occupation in this remarkable ecosystem, we continue to be amazed by the number of previously undiscovered sites.” This research sheds new light on the rich and complex history of the Amazon and its Indigenous peoples.

Probability model of pre-Columbian earthworks across Amazonia. (A) Predicted probability of earthwork presence for 1-km2 cells across six Amazonian regions using an inhomogeneous Poisson process predictive model: central Amazonia (CA), eastern Amazonia (EA), Guiana Shield (GS), northwestern Amazonia (NwA), southern Amazonia (SA), and southwestern Amazonia (SwA). Areas not modeled (NA) are greyed out. (B) Predictive probability function for the number of as yet undetected earthworks; the dark area under the curve represents the credibility interval (CI) of the probabilities associated with each number. (C) Boxplot of the estimated relative contribution of each covariate; the yellow diamond indicates the mean value. SCC, soil cation concentration; TPI, terrain position index; HAND, height above the nearest drainage. (D) Individual predicted probability of earthwork presence against intensity covariates. Credit: Science (2023). DOI: 10.1126/science.ade2541

The Amazon rainforest, long perceived as an untouched wilderness, is revealing its hidden history through a groundbreaking study. Led by Hans ter Steege from the Naturalis Biodiversity Center and Utrecht University, the research predicts that approximately 90% of the Amazon has a minimal chance of containing pre-Columbian earthworks. This suggests that extensive human engineering primarily shaped around 10% of the forested areas.

Carolina Levis, from the Federal University of Santa Catarina, underscores the shift in our understanding of the Amazon. “Ecologists once saw it as an untouched expanse, but now, by combining evidence of pre-Columbian activities, we’re uncovering the extent of human influence, from engineering to agriculture. These ancient societies possessed advanced land and plant management techniques, knowledge that still exists within present-day communities, offering inspiration for coexisting with the forest without harming it.”

The quantitative findings in this study, including those in the paper’s title, rely on a methodology developed by Guido Moreira at the Universidade Federal do Rio de Janeiro and Dani Gamerman, employing Bayesian statistics. This method employs data augmentation to account for unobserved earthworks and their distribution.

While many earthworks have been spotted through Google Earth imagery, the Amazon’s vastness and remote areas present challenges. This research provides testable predictions for undiscovered sites of monumental significance, awaiting exploration within the forest’s depths.

Luiz Aragão, head of the Earth Observation and Geoinformatics Division at INPE and a leader in the research, highlights the study’s multifaceted impact. “This research signifies a remarkable scientific and technological leap, advancing archaeology with newfound discoveries, unveiling the extent of human impact on the environment, and revolutionizing applied computing for analyzing LIDAR data and statistical modeling.”

Moreover, the study carries political implications for the Indigenous land demarcation debate in Brazil. The authors argue that it provides substantial evidence of Indigenous peoples’ longstanding presence in the Amazon, emphasizing the need to protect their territories, languages, cultures, and heritage, rooted in ancient history rather than recent timelines.

Source: Max Planck Society

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