In the Bolivian Amazon, not far from the border with Brazil, people who lived between 1,500 and 600 years ago created settlements with a complex network of fortifications, roads, canals and dams, apparently controlled from the top of rammed earth pyramids that surpassed the 20 meters high.
The details of this lost civilization, presented in the latest issue of the scientific journal Nature, should bury once and for all the idea that the Amazonian territory was “only bush” before the arrival of Europeans.
“These platforms and pyramids were artificial from the base to the top. In fact, they were built on top of terraces up to 6 meters high, which, in themselves, already correspond to an incredible amount of work”, says Heiko Prümers, researcher at the German Archaeological Institute and coordinator of the new study.
Along with the Bolivian Carla Jaimes Betancourt, from the University of Bonn (also in Germany), Prümers has been working in the Llanos de Mojos region for about 20 years, mapping the archaeological sites of the so-called Casarabe culture, which spread over a territory of 4,500 kmtwo (about three times the area of ​​the city of São Paulo).
The Llanos de Mojos are formed, for the most part, by a type of periodically flooded savannah – something that, from the Brazilian point of view, could be seen as a mixture of the Pantanal and the Cerrado, although the area also has more stretches of forest. dense.
Several previous studies already indicated that the pre-Columbian population of the region adopted sophisticated systems of land management, such as artificial raised fields where they could plant even during the floods, channels to regulate the distribution of water, ramps and roads that facilitated displacement in the season. rainy
However, the still dense vegetation cover in much of the region used to hinder attempts to have an overview of the changes made by the peoples of the past in the territory. As a result, archaeologists have turned to “lidar” (pronounced “laider”), technology that can be described as an equivalent to radar that uses lasers.
The “dealers” aboard planes or helicopters fire pulses of infrared lasers towards the ground. The time it takes for light to “hit” the ground and be reflected back to the device’s detectors, as if it were an echo, is used to calculate the details of the relief below with great precision, allowing the creation of maps of the terrain that do not are hampered by the presence of trees.
Thanks to the “lidar”, Prümers, Betancourt and their colleagues managed to map a network of 24 archaeological sites of the Casarabe culture, two of which, named Cotoca and LandÃvar, are city-sized, with 147 hectares and 315 hectares, respectively (one hectare corresponds to the area of ​​a football field).
Both have an apparent ritualistic or governmental center formed by the terraces and the pyramids on top of them. In addition, they were surrounded by three concentric defensive structures, formed by a moat and a wall or bulkhead, also made of beaten earth.
“These centers are the product of a long process. Like Rome, they were not built in a single day”, compares the German researcher. “The three ‘rings’ of defensive structure at the Cotoca site, for example, indicate constant remodeling and adaptations caused by a growing population.”
In addition, the other sites scattered throughout the region indicate a hierarchy of settlements with different sizes and functions. Some of the locations have smaller ceremonial platforms (but no pyramids); others appear to be small and medium-sized villages. It’s as if there were two metropolises, some regional capitals and more modest localities, let’s say.
According to Prümers, the linguistic and cultural diversity of the region today is too great to know which people were responsible for the construction of the structures. There are indications of commercial contacts with the region of Cochabamba, also in the Bolivian Amazon, and with the Brazilian Amazon, and even with the Andes (in this case, few objects made of copper).
The question is to what extent the discoveries in Bolivia are really unique in the Amazon context. Several areas of the Brazilian Amazon, such as the Alto Xingu and the island of Marajó, have monumental structures, such as large roads, fortifications and even artificial platforms made to shelter settlements during floods, albeit on a smaller scale.
“I followed this story from the beginning because I was in Bolivia in 2019, when some of these flybys were made”, says Brazilian archaeologist Eduardo Góes Neves, from USP, one of the main researchers of the pre-Columbian Amazon in the country. “Heiko and Carla, for me, are the best field archaeologists in the Amazon today, and this work is the crowning achievement of their efforts. For the time being, in fact, it is something unique, although we don’t know what might come up.” in the future.”
