The vegetation of the Amazon hides the remains of an extremely complex urban fabric east of Ecuador, which the natives began to build 2,500 years ago. The framework, erected over a millennium, includes streets and tracks up to 25 kilometers long dug into the earth, more than 6,000 platforms that supported homes and ceremonial structures, and large areas of agricultural cultivation adapted to the characteristics of the terrain.
The discovery, published this Thursday in the journal Science, shows the oldest urban network built—and excavated—by humans in the Amazon. “It is another vivid example of the underestimation of the double heritage of the Amazon: environmental, but also cultural, and therefore indigenous,” the authors say in the article.
To reveal the last secret of the largest rainforest in the world, it has been necessary to combine the findings of more than 20 years of archaeological, geoscientific and archaeobotanical research, with Lidar mapping technology, from the English light detection and ranging. ). The tool, a laser mounted on an airplane or helicopter, allows you to create a 3D map of the ground with an accuracy of millimeters, something key to finding evidence of human activity.
The interdisciplinary approach of the study has been key to characterizing the societies that lived on the banks of the Upano River, at the foot of the southernmost volcano in Ecuador. Field work made it possible to date the occupation of the settlements, learn about the culture and diet of its inhabitants, and identify the area as archaeologically rich. Lidar has multiplied the magnitude of the scenario, revealing that the sites made up a very complex urban and agricultural fabric.
Stephen Rosain, the archaeologist at the French National Center for Scientific Research (CNRS) who has led the two decades of research, expected, after his in situ observations, that aerial technology would reveal a few hundred human constructions in the 300 square kilometers of terrain they studied. Mapping showed the existence of more than 6,000. “It is a valley completely modified by the pre-Columbians,” he explains, surprised, in statements to La Vanguardia.
Much of the foundations of the buildings are spread across fifteen settlements, five of which were densely populated. Even so, the presence of small housing complexes isolated from urban centers was not strange either, especially to the south, where the land was flatter and more spacious. Throughout the territory, life was organized around plazas and ceremonial structures connected by streets.
Urban centers and solitary complexes were linked to each other by a network of tracks dug into the ground, some of which extended in a straight line for more than 25 kilometers, crossing hills and deformations of the terrain. “The inhabitants modified the entire landscape,” details the expert, for whom “these modifications were functional, but also symbolic.”
The symbolic load is due, according to the CNRS archaeologist, to the fact that the roads were not, in reality, necessary to move around the area. Much less was it necessary for them to be completely straight. “Its function was to inscribe on the land relationships with other groups and other communities,” he notes.
The investigation has also revealed that the settlements lived from agriculture, and that their agricultural practices adapted to the orography of the land. In the southernmost areas, the inhabitants established hectares of fields limited between them by ditches. The agricultural areas were surrounded by drainage canals, which were responsible for removing excess water in case of flooding.
In the most mountainous areas, the inhabitants' agricultural strategy changed to terraces, a kind of giant staircase dug into the mountain to take advantage of its relief for cultivation. Fields and terraces surrounded the tracks that ran through the territory, forming an almost continuous fabric of human occupation throughout the study area, and even beyond.
“What we are discovering now is that the roads go up into the Andes, and that there are structures in the Andes themselves. We don't know how far, so it will be interesting to do a Lidar to the top to see if the phenomenon, in addition to being horizontal, is also vertical, and rises to the high mountains of the mountain range," Rosain reveals. To do this, the expert needs to find funding that, he hopes, will arrive after his last publication.
“The Amazon is one of the places in the world that preserves the most secrets of its past, and that waits for archaeologists to do their work,” concludes the researcher. The number of archaeologists specialized in the largest jungle in the world has not stopped growing in recent years, but the challenge they face is enormous. A study published in Science at the end of 2023 estimated at least 10,000 anthropogenic structures that remain hidden and unknown in the densest vegetation.
