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Deep in the Amazon, researchers have uncovered a complex of ancient cities — using laser technology

The Current16:20Huge ancient city discovered in Amazon

“Wow” was all archaeologist Stéphen Rostain could say when LiDAR (light detection and ranging) laser technology revealed several ancient cities hidden deep in the Amazon rainforest.

“It’s a gift for an archaeologist,” he told The Current‘s Matt Galloway. 

Using the laser-scanning technology, researchers have uncovered a complex network of farmland, roads and neighbourhoods in Ecuador’s Upano River Valley.

The cities are believed to be between 2,000 and 3,000 years old, according to Rostain, who works for France’s National Center for Scientific Research. His group’s findings were recently published in the journal Science.

“In the Upano, it’s a completely new approach [to] the human past in the biggest rainforest of the world,” he said.

LiDAR leads the way

Rostain has been working in the Upano River Valley for years. He says he started excavating there 25 years ago, so he’s known about the site with earth mounds in the area for decades.

“What we didn’t [know] at this time, it was the size and the global organization of this construction,” he said. “This is really new, and the LiDAR showed to us a map of this road connecting cities.”

LiDAR was introduced to the excavation in 2015, when Ecuador’s National Institute for Cultural Heritage funded a LiDAR survey of the valley. 

As part of the survey, specially equipped planes beamed laser pulses through the forest’s vegetation, and measured their return path.

This LIDAR image shows a main street crossing an urban area, creating an axis along which complexes of rectangular platforms are arranged around low squares at the Copueno site, Upano Valley in Ecuador. (Antoine Dorison, Stéphen Rostain via AP)

According to archaeologist Jay Silverstein, a senior lecturer at Nottingham Trent University in England, this method allows researchers to create a terrain model of the ground underneath the forest.

“You’ve basically skimmed off all the trees and you’re actually looking at the shape of the earth,” he told Galloway. “Then we start to be able to see the patterns of what we call anthropogenic, or things that were made by humans as opposed to nature.”

For Rostain, this method is indispensable because it allows the exact shape and size of the ground to be reconstructed without harming the forest itself.

Rostain says nothing gets destroyed by LiDAR, noting that the technology maps out the terrain without cutting trees or destroying the archaeological site. “It’s just perfect.”

Whether you’re we’re dealing with Highlanders in Papua New Guinea or villagers in Mexico … we adapt to our environments, we figure ways to organize ourselves.-Archaeologist Jay Silverstein

Silverstein said science can indeed be destructive, as damage created during excavation can’t be undone. That’s why using non-destructive archaeology like LiDAR is extremely important.

“We are developing more and more non-destructive techniques that allow us to to plan our excavations much better to understand what we’re looking at and on the large scale before we do our small-scale excavations,” he said.

Humankind’s potential — and fragility

As significant as this discovery is, Silverstein warns against making any assumptions about this civilization based on first impressions.

“When I teach students or younger archaeologists, I tell them that your first impression, your gut instinct, your feeling of what you see when you first see, it is wrong,” he said.

“You can’t go with your gut so much. You need to build the evidence.”

WATCH: What’s at stake for the climate, deep in the Amazon

What’s at stake for the climate, deep in the Amazon

The Amazon rainforest plays a crucial role in regulating the global climate, but it’s under serious threat from deforestation. CBC’s international climate team ventures deep into the forest with scientists to learn how climate change is affecting it, and what’s at stake in the fight to save it.

In this case, Silverstein said assumptions shouldn’t be made about what the geometric shapes revealed by LiDAR represent. 

“You don’t know if you’re really talking about palace plazas or agricultural fields when you see a rectangular shape in the ground,” he said. “There’s a big difference of what it means when understanding that society.”

Nevertheless, these findings are confirmation of humanity’s potential, said Silverstein.

“Whether you’re we’re dealing with Highlanders in Papua New Guinea or villagers in Mexico … we adapt to our environments, we figure ways to organize ourselves,” he said. 

“And given the opportunity and the resources and good fortune, we will organize ourselves and create more complex societies and we’ll figure out how to better manage our water and build roads and build houses.”

There may be a grim lesson to be learned from these findings, according to Silverstein: civilization is fragile, and there’s no guarantee that our societies will be around in the future.

“Everyone who lived in those ancient societies thought their society was fine and that they were going to live on forever, and that their children would live there and their grandchildren and so on,” he said. “But something happened and it didn’t.”

“We blithely go through life and we get our warnings of climate crisis and warfare and threats. But we more or less assume that we’re going to be here tomorrow and living just like we do today —until it happens.”


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