Blast from past: Remnants of sprawling ancient cities found in Amazon

The Amazon valley looked like so many others, with a muddy river snaking through dense forest, except that this one had earthen mounds rising at clear right angles and ditches carving long straight lines through the soil.

In this rainforest, archaeologists say, lay the bones of sprawling ancient cities: earthworks that were once roads, canals, plazas and platforms for homes where thousands of people had lived for centuries, long before Europeans ever tried to chart South America. The cluster of interconnected cities was only recently mapped in the Upano Valley of eastern Ecuador, a research team reported this month in the journal Science, working off decades of research and laser-mapping technology that has helped to revolutionize archaeology.

With the technology, called lidar, researchers were able to pierce the forest cover and map the ground below it, documenting five major settlements and 10 secondary sites across more than 115 square miles.

Radiocarbon dating found that people lived there from around 500 B.C. to between A.D. 300 and A.D. 600, which would make the settlements some of the oldest found so far in the diverse landscapes of the Amazon.

“It’s a huge contribution to Amazonian archaeology,” said José Iriarte, an archaeologist at the University of Exeter who was not involved in the research.

This region, where the Amazon reaches the eastern slope of the Andes, had long been thought of as an area “with nothing really happening there,” he said.

Now, he said, “we have this major, idiosyncratic cultural development.” Stephen Rostain, the lead researcher of the study, said he was impressed by the complexity of the cities and the amount of work needed to build them.

The “perfectly straight roads” that connected them were one sign of the cities’ sophistication, he said, adding that they would have required engineers and workers, farmers to provide food, and some sort of chairman, chief or king to lead “a specialized and stratified society.”

The original construction was done by groups from the Kilamope, and later, Upano cultures, the researchers said, adding that people of the Huapula culture lived in the area between 800 and 1200.

The team excavated artifacts, including painted pottery and jugs with the remains of traditional chicha, the corn-based drink that remains a mainstay of the Andes region today. Though archaeologists have long known about earthworks in the area, lidar — which pierces foliage with laser pulses from airplanes and has helped find hidden Mayan sites and ancient Cambodian cities — revealed the scope of the settlements.

They eventually mapped more than 6,000 earthen platforms, connected by roads and laid across a landscape molded to control water and cultivate crops. The researchers determined that some of the earthen mounds were residential platforms, and said in the paper that other, larger complexes might have served a “civic-ceremonial function.” Particularly striking, archaeologists said, were the systems of roads and farming — how ancient people drained away the heavy rains along the Andes’ eastern slopes to take advantage of fertile volcanic soil.

The writers are reporters with NYT©2024

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