LiDAR Reveals up to 30,000 Structures of a LOST Civilization

Hello everybody and welcome to Ancient Architects. Please subscribe to the channel for regular content on ancient architecture as well as all the latest news from the world of archaeology. LiDAR technology has revolutionised archaeology in South America, a part of the world that's hard to explore by conventional methods and that's because of the dense Amazon rainforest. But LiDAR allows us to see through the dense jungle to see what, if any, human structures are hiding below. In recent years, hundreds of new structures have come to light and this week, thanks to a new study that was published in Nature, hundreds more have been discovered, with an estimated total of 30,000 earthworks hiding beneath the trees. Yes, 30,000. A vast network of geometric earthworks suggest that southwestern Amazonia once supported a highly organised society, numbering as many as 3 million people. It's absolutely astonishing that such a civilization could be forgotten. Well, not anymore. In the newly published paper that's titled Over 20,000 Pre-Colonial Earthworks in the Southwest Amazonia by Marti Parsonen et al, which I've linked below in the description, experts estimate that the cultural landscape they call the Aquarii Civilization covered approximately 183,000 square kilometers across parts of present-day Brazil, Bolivia and Peru. The civilization peaked between 100 and 300 AD and had between 1.25 and 3 million inhabitants. The technology that was used to find the earthworks is airborne LiDAR, and it surveyed a vast area back in 2024, sending laser pulses through the gaps in the forest canopy, allowing researchers to construct detailed models of what's lying on the ground beneath the dense vegetation. There were 10 flights covering 4,497 square kilometers, and a total of 432 earthworks were identified, 396 more than was previously known in the same region from satellite images. Yes, there's a stark difference between LiDAR mapping and satellite observation. In one deforested section, 156 earthworks were identified with LiDAR, but in the past only 30 were known about from satellite images. The results of the new survey show that remote imagery may have vastly underestimated the true number of structures by a factor of 5. Using these new observations alongside the earlier satellite surveys, the researchers calculated that the wider landscape likely contains between 24,000 and 30,000 earthworks, and about two-thirds of these structures are believed to belong to the Aquarii civilization. The structures identified so far were built between 600 BC and 850 AD, and we see a variety of constructions from deep ditches, raised embankments, enclosed spaces and there are also roads arranged in circles, squares and more complex geometric forms. It really is a fine example of historic planning. Most structures cover between 0.35 and 14 hectares, but the largest covers something like 50. The surrounding ditches measure between 9 and 13 meters across, and they reach depths of up to 5 meters. Individual enclosures were sometimes connected to roads or combined into groups containing as many as 8 monuments. LiDAR also showed that some earthworks also had an outer embankment surrounding it. Experts don't believe that we're looking at military fortifications and that they're likely public political and ceremonial centres, places where communities from the surrounding landscape assembled periodically. It's believed the structures were not lived in all year round. Their role may have resembled gathering centres like those later used in parts of the Inca world, where different groups met for communal activities like ritual performances, music, dance, sport and political negotiation. Whatever their true nature, right now we don't know. But we do know that building and maintaining these enormous structures for more than 1,000 years would have required organised labour, coordination and a keen understanding of geometry. The big thing that comes out of this new study is the previous underestimation of the size of the population. When just 200 earthworks were known about in the region, experts estimated that 60,000 people inhabited the area. But now with the monument estimation moving into the thousands, the total population was likely in the millions. And yes, these calculations are based on assumptions, but it's calculated guesswork, using evidence from the later mound villages and indigenous ceremonial centres. Within the 85,000 square kilometre core area, population density may have reached 13 to 33 people per square kilometre, which is much higher than the previous estimates for the Amazon rainforest. And although it's still early days regarding our knowledge of the Aquarius civilisation, evidence suggests they did far more than build structures, as they were actively shaping the forest around them. They cultivated chilli peppers, peanuts, sweet potatoes, squash and maize, they grew Brazil nut trees and edible palm species, and their modern distribution reflects centuries of human planting and management. They also repeated the act of burning bamboo ridge areas to maintain fertile soils. Water sources were also well managed, as were agricultural plots and forest gardens, and their legacy is the composition of today's vegetation, soil fertility and biodiversity. Why this civilisation came to an end is still unknown, but later communities did build mound villages in some parts of the same region, indicating cultural transformation rather than the complete disappearance of human settlement. The new study that's published in Nature and linked below, reveals only a tiny amount of what may remain beneath the canopy of the rainforest, and in the coming years, the history of South America will certainly keep being rewritten. Thank you very much for watching this episode of Ancient Architects. If you enjoyed the video, please subscribe to the channel, please like the video and please leave a comment below. Thank you very much.