Aerial survey reveals the largest previously discovered pre-colonial city in the Amazon, connected by an extensive road network.

“This settlement is much larger than other settlements in the Amazon,” he says. Stefan Rostain at the French National Center for Scientific Research in Paris. “They are equivalent to Maya sites.”

Additionally, these cities are between 3,000 and 1,500 years old, making them older than other pre-Columbian cities found in the Amazon. It is not clear why the people who built them disappeared.

The Amazon rainforest was thought to be largely untouched until Italian explorer Christopher Columbus arrived in the Americas in the 15th century. In fact, the first Europeans reported seeing many farms and towns in the area.

These reports, long ignored, have been borne out in recent decades by the discovery of ancient earthworks and vast expanses of black soil created by farmers.According to some estimates, the pre-Columbian population of the Amazon was Up to 8 million.

Since the 1990s, Rostain and his colleagues have been studying archaeological sites in the Upano Valley of the Amazon River in Ecuador, in the foothills of the Andes Mountains. Traces of an ancient settlement were first discovered there in his 1970s, but only a few remains have been excavated.

In 2015, Rostain’s team conducted an aerial survey using LIDAR, a laser scanning technology that can create detailed 3D maps of the surface beneath most vegetation, revealing features that are normally invisible to the eye. did. The findings, which have just been published, show that the settlements were much more widespread than anyone realized.

The survey revealed more than 6,000 raised earth platforms within an area of ​​300 square kilometers. These are the sites where wooden buildings once stood, and excavations have revealed postholes and fireplaces in these buildings.

Most of the platforms are approximately 10 x 20 meters and 2 meters high and are believed to be the site of residential buildings. The largest was 40×140 meters and 5 meters high and was considered the site of a monumental building used for rituals.

Surrounding the home were fields, many of which were drained by small canals dug around them. “The valley has been almost completely modified,” Rostain says.

Analysis of pottery suggests that corn, beans, caniolk, and sweet potatoes were cultivated.

Overall, there were five major settlements in the study area. According to Rostain, these could be described as garden cities because of their low density of buildings.

The survey also revealed a network of straight roads made by digging out soil and piling it up on the sides. The longest span at least 25 kilometers, but may extend beyond the surveyed area.

What's strange, Rostain says, is that the people of Upano went to great lengths to straighten the road. For example, in one place they dug down 5 meters instead of along the contour line. So the road probably had a symbolic meaning, he says, since there was no practical reason to make it straight.

There are traces of defensive structures such as ditches in places, suggesting that there may have been some sort of conflict between groups.

In the rest of the Amazon, many settlements were abandoned after the arrival of Europeans, as most of the population died from disease and violence, probably caused by the invaders.

However, the Upano artifacts dated by Rostain's team are all more than 1,500 years old, suggesting that the valley settlements were abandoned after this period, long before colonial times. doing. It's not clear why, but the team found layers of volcanic ash, suggesting a series of eruptions may have forced people to leave the valley.

“This demonstrates the unprecedented degree of complexity and density of payments in this early period,” he says. michael heckenberger at the University of Florida. “The authors rightly conclude that the complexity and scale are now comparable to well-known cases such as the Maya.”

“This is the largest complex containing a large settlement ever found in the Amazon,” he says. charles clement at the National Amazonian Institute in Manaus, Brazil.

They were also found in an area of ​​the Amazon that other researchers had concluded was sparsely inhabited during the pre-Columbian period, Clement said.