The vast urban landscape, which included interconnected camps, villages, cities and monumental centers, thrived in the Amazon rainforest more than 600 years ago.
In present-day Bolivia, members of the Kazaraba culture built an urban system that included flat, elevated embankments several kilometers long, canals and reservoirs, researchers report 25. the nature.
This low-density urban spread from pre-Columbian times was previously unknown in the Amazon or anywhere else in South America, say archaeologist Heiko Prumers of the German Archaeological Institute in Bonn and colleagues. Instead of building huge cities densely populated with people, a significant population of Casarabe spread into a network of small and medium-sized settlements that included a lot of open space for agriculture, scientists conclude.
Air lasers peeked through dense trees and ground cover to identify structures from that low-density urban network that had long eluded terrestrial archaeologists.
Earlier excavations have shown that Casarabe farmers, fishermen and corn hunters inhabit an area of 4,500 square kilometers. For about a century, researchers knew that the people of Kazarabe formed complex pottery and built large earthen mounds, embankments and lakes. But these finds were located in isolated forest sites that are difficult to excavate, leaving a mystery about the reasons for the construction of the mounds and the nature of the Kazaraba society, which existed from about 500 to 1400.
Prumers’ team decided to look through the lush cover of the Amazon from above, with the goal of finding the remains of human activity that usually remain hidden even after careful research of the terrain. The scientists used a helicopter that carried special equipment to fire laser pulses on the Amazon forest, as well as on lawns. These laser pulses reflect data from the Earth’s surface. This technique, called light and range detection, or lidar for short, allows researchers to map the contours of now-darkened structures.
Looking at the new lidar images, “it is obvious that the mounds are platforms and pyramids that stand on artificial terraces in the center of well-planned settlements,” says Prumers.
Prumers’ team conducted research as a leader in six parts of the ancient territory of Kazaraba. The leader’s data revealed 26 locations, 11 of which were previously unknown.
Two locations, Kotoca and Landivar, are much larger than the others. Both settlements have rectangular and U-shaped platform mounds and cone-shaped earthen pyramids on top of artificial terraces. Curved trenches and defensive walls border each site. Roads radiate from Kotoka and Landivara in all directions, connecting these primary sites with smaller sites with fewer platform mounds which then connect to probably small campsites or areas for specialized activities, such as slaughtering prey.
The Kazarabe Society’s network joins other ancient and modern examples of low-density urban sprawl around the world, says archaeologist Roland Fletcher of the University of Sydney. These sites question whether only cities with centralized governments that ruled people who were crammed into neighborhoods on narrow streets, such as 6,000-year-old Mesopotamian metropolises, can be defined as cities.
Some former urban settlements organized around crop cultivation spread over 1,000 square kilometers or more in tropical regions. This includes sites such as Greater Angkor in Southeast Asia about 700 to 800 years ago and interconnected Mayan sites in Central America dating back at least 2,300 years ago (SN: 29.4.16; SN: 27.9.18). Today, expanded areas outside major cities, especially in Southeast Asia, mix industrial and agricultural activities for tens of thousands of kilometers.
Clusters of interconnected settlements of Kazarabe ranged from 100 square kilometers to more than 500 square kilometers. Widespread settlements in the comparable area include 6,000-year-old sites from the Tripila culture in Eastern Europe (SN: 19.2.20).
Tropical forests that have largely remained unexplored, such as the Congo Basin in central Africa, have probably hosted other early forms of low-density urban development, Fletcher predicts.
Only further excavations led by evidence of the leader can begin to reveal the size of the Casarabe population, says Prumers. Whether Casarabe’s primary sites were seats of power in the upper and lower classes also remains unknown, he added.
The urban spread of the Kazaraba culture must have included a significant number of people in the centuries before the Spaniards arrived and the indigenous population declined, largely due to disease, forced labor and slavery, says archaeologist John Walker of the University of Central Florida at Orlando.
Whatever the Casarabe honchos had in mind as their network of tropical settlements expanded, he says, “we may have to put aside some of our solid ideas about what the Amazon is and what the city is, to better understand what happened. .