Remains of ancient cities found in the Amazon

The Amazon valley looked like many others, with a muddy river winding through a dense forest, except that this one had mounds of earth rising at clear right angles and ditches that carved long straight lines into the ground.

In this rainforest, archaeologists say, lie the remains of great ancient cities: works of earth that were once roads, canals, plazas and home platforms where thousands of people had lived for centuries, long before Europeans attempted to map South America.

The cluster of interconnected cities was recently mapped in the Upano Valley in eastern Ecuador, a research team reported in Science magazine, working on decades of research and laser mapping technology called lidar. The researchers used lidar to pierce the forest canopy and map the ground beneath it, documenting five main settlements and 10 secondary sites across about 300 square kilometers. Radiocarbon dating discovered that people lived there from around 500 BC between 300 and 600 AD, which would make the settlements some of the oldest found in the Amazon.

Stéphen Rostain, the lead researcher, said he was impressed by the complexity of the cities and the amount of work needed to build them. The “perfectly straight roads” connecting them would have required engineers and workers, farmers to provide food and some kind of president, chief or king to lead “a specialized and stratified society,” he said.

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

The researchers mapped more than 6,000 land platforms, connected by roads and arranged across a landscape. molded to control water and plant crops. They determined that some of the earthen mounds were residential platforms and that other larger complexes may have served a “civic-ceremonial function.”

Particularly surprising were the road and agricultural systems—how ancient people drained heavy rains down the eastern slopes of the Andes to take advantage of the fertile volcanic soil.

Researchers suggested that up to 30,000 people may have lived at one time in the Upano Valley.

Rostain said the scale and complexity of the cities showed that their inhabitants were more than “hunter-gatherers lost in the jungle looking for food.”

Eduardo Neves, an archaeologist at the University of São Paulo who was not involved in the study, said continued research could help protect the Amazon from deforestation.

“Part of the destruction is based on the idea that the Amazon has never really been colonized in the past, that there were never many people there and that in some ways it is a no man's land,” he said. But this type of research “is really important because it adds to the evidence that shows that the Amazon was not an empty place.”

By: ALAN YUHAS and JESUS ​​JIMÉNEZ