In early 2022, scientists using remote sensing technology made a discovery worthy of a Jules Verne novel: a network of lost cities beneath the dense mixed vegetation of the southwestern Amazon. Evidence of the past spoke of a complex civilization dating from 400 A.D. The Casarabe people who once lived there constructed 22-meter-high conical pyramids, elevated roadways and terraces, and a sophisticated water management system of interlocking reservoirs and canals. Led by Heiko Prümers of the German Archaeological Institute in Berlin, archeologists from several universities consider the settlement system “a singular form of tropical agrarian low-density urbanism.”
Their study, published in Nature last May, bolsters an already substantial body of research debunking the long-held notion that the Amazon rainforest has always been empty and untouched, a hostile environment where only a few small isolated tribes could survive.
While archaeologists working in the tropics may not have the kinds of stone ruins that ancient sites in drier climates offer as indications of ancient civilizations, the Amazon does flag a lot of clues of human interaction with the landscape. While the environment is basically too wet to preserve much, researchers have been unearthing artifacts and dating the ones they do find to suggest that as many as 8 to 10 million people once populated the rainforest.
According to Eduardo Góes Neves, professor of archaeology at the University of São Paulo, Indigenous Peoples have lived in the vast region for at least 14,000 years. Centuries before the arrival of European colonizers, these communities domesticated local trees and plants for food; traded with other, more northerly Indigenous groups; and even enhanced the region’s fragile, low-nutrient soils to improve agriculture within the tropical ecosystem.
Their impact can be seen today in the very makeup of the Amazonian landscape.
For example, approximately 16,000 known tree species are found in the Amazon biome, but almost half of the total biomass comprises just 227 species. This hyper-dominance of a relative few species is mostly the result of human management in the past, says Neves.
What’s more, manmade deposits of rich black soil, known as Amazon Dark Earths (ADEs) have been found throughout the region, indicating one way ancient forest dwellers were able to maximize food production and support large numbers of people. These areas indicate people’s continual addition of charcoal and domestic waste such as animal bones changed soil chemistry, creating nutrient-rich patches of land and an agriculture that was both intensive and sustainable.
“Native populations created the Amazon that we know today,” says Neves. “They took from the forest in a way that was very productive.”
Evidence of using controlled fire to clear undergrowth or increase the abundance of certain species in tropical forests around the world offers more proof that, as Patrick Roberts, leader of the isoTROPIC Research Group at the Max Planck Institute for Geoanthropology, puts it, “people actually lived in and with tropical forests… using them, changing them, from at least 45,000 years ago.” Evidence found in tropical forest regions such as Borneo, New Guinea and the lowlands of Sri Lanka are together changing our perspectives on the role these environments have played in our past, he says.
Ancient people used fire to modify vegetation and also moved plants and animals, says Roberts, author of the 2021 book Jungle: How Tropical Forests Shaped World History – and Us. In it, he argues that over millennia, tropical forests have shaped almost every aspect of life on earth and provides compelling evidence showing how humans evolved in jungle landscapes, developing systems of agriculture and infrastructure. Aside from domesticating certain species, people preserved patches of forest for hunting and gathering, maintaining a very mixed diet. “Even once we get to urbanism, we frequently see these very mixed landscapes, with cultivation supporting the urban network.”
While tropical forest archaeology paints a fascinating, much more complete picture of Indigenous Peoples interacting with their environment, perhaps the most salient question today remains: How does this knowledge help guide us in present-day policy-making?
Conservation policies, for example, are only beginning to support Indigenous Peoples’ rights based on this information.
“Ten years ago, some famous conservation biologists were really upset with the things that we (archeologists) said,” says Neves. “They said, ‘Oh you guys are just providing a blueprint for the Amazon to be destroyed when you say a lot of people can live there.’”
That attitude is now changing. “Most conservation biologists have a different perspective and have accepted the idea that there’s no contradiction between protecting an area and having traditional societies living [there]. Actually, the opposite. To protect the Amazon, we have to have some measure of human interference.”
He emphasizes that policymakers need to pay attention and learn from the forest’s traditional societies, river-dwellers, rubber tappers and Indigenous Peoples, some of whom – like the Kuikiro people of the Xingu region – are still creating ADEs.
The basic idea underlying their practices, says Neves, is to produce diversity through agroforestry. “If you look at traditional agricultural systems or cultivation in the tropics, in the Amazon, it’s really based on the different cycles of plants. It’s a cycle that is very different from other types of agriculture, which is often a yearly one. So you have tree cropping, or cultivation, and it’s a long-term process. It can take decades and even centuries. This is a long-term engagement with the landscape.”
Fire management is another example of Indigenous expertise that should be harnessed today, says Roberts, as increasingly dangerous wildfires tear through forests not only in the Amazon but also in.ecosystems across the world, from Canada to Australia.
In Australia’s rainforests in northeastern Queensland, Indigenous Peoples used fire to clear the forest floor or make pathways between settlements, shaping the boundaries of different forest types, he says. “So you would have very fire-resistant forest being promoted. But if Indigenous People and their ideas are marginalized, climate change can turn even the wet tropics into a tinderbox.”
Letting go of certain logic
While agriculture sustained relatively large populations in the distant past, farming methods practiced by Brazilians of European descent have only proven to be hugely destructive to the ecosystem. Cattle ranching, and soy and sugar cane cultivation are the very antithesis of the long-term process Indigenous people used to maintain and manage the forest while producing food, and lie at the heart of the Amazon’s dangerously high deforestation rates today.
Neves believes that people should “disentangle this logic of production” in the Amazon. “We should just leave it the way it is. This idea that it’s there to be grabbed is a very colonialist idea.”
Instead, he suggests, forest dwellers should be compensated for ecosystem services and well remunerated for their non-timber products. “Let’s find ways to do that,” he says, “because they have to send their kids to school, they need health services. It’s important to find ways to keep these people living in these places where they live.”
According to Roberts, support for tropical forest archaeology is growing, as well as “an increasing drive in archaeology as a whole to make itself useful in the present.” The unique long-term perspective of researchers who study the ancient past is now being taken into consideration in Intergovernmental Panel on Climate Change (IPCC) reports, for example.
“To fix today’s climate and biodiversity loss problems, we need to start seeing ourselves as global communities rather than just nations,” he says.