When most of us think about clearing away the Amazon rainforest, we have visions of chainsaws and scorched earth. In recent years, vast swathes of the rainforest have been razed for cattle pastures, roads and other ventures, laying waste to much of the world's signature tropical biome.
It would be tempting to dismiss the destruction as the inevitable result of human encroachment. But evidence suggests that the Amazon was never entirely devoid of settlement. Thousands of years ago, the rainforest may have been a hive of human industry, home to teeming communities who multiplied and migrated, even as they curated, culled and refashioned the forest according to their needs—all of this millennia before the first caravels pitched up in the New World.
The findings suggest that people and wilderness can coexist, if they strike the right balance.
"The future of the Amazon lies in the past," says Eduardo Neves, a leading Amazonian archeologist.
The evidence comes from the work of Vinícius Peripato, a researcher with Brazil's National Space Institute. Using the latest in remote sensing tools, he and his colleagues figured out a way to virtually peel away the forest to see what's hidden below. While the research must still be verified on site, the implications are hard to miss. It turns out that the sprawling river basin that had long been dismissed as a hollow wilderness, devoid of all but the most rudimentary endeavor and social structures, was in reality a systemically nurtured habitat.
Scouring data generated by airborne sensing technology, Peripato and his colleagues turned up vestiges of what they described as a hidden world—ancient villages, roads, weirs and orchards—that dates back thousands of years, they write in an October article for the journal Science. Their computer models projected that at least 10,000 and perhaps as many as 24,000 previously undetected pre-Columbian "earthworks" await discovery below the storied canopy. The findings promise not only to rewrite the story of the Amazon; they also shine a light on how millennial indigenous practices of managing the standing forest could help avert runaway biodiversity loss and strengthen one of the world's best defenses against climate change.
The scientists' strategy—call it digital deforestation—entails scanning the landscape with LIDAR, light detection and ranging, a sampling technology that pulses tens of thousands of beams of light per second down from the skies and measures the time it takes them to bounce back. The barrage of light (15 pulses for every one-meter pixel per second) renders an impressively detailed, computerized picture of the contours and dimensions of structures below.
LIDAR was first deployed in the Amazon to assess forest biomass on the theory that the volume of carbon stored in the trees was a proxy for gauging the health of the ecosystem. A few years ago, scientists decided to rake over the data again. The new findings promise to help redraw the map of human habitation in the river basin, and so challenge the enduring trope of the Amazon as a green desert.
That conceit gained traction in 1971, when celebrated U.S. archeologist Betty Meggars branded the Amazon a "counterfeit paradise," alluringly lush but in reality cursed by infertile soils, unfit to support all but the simplest communities. Meggars's dictum defined the terms of scientific debate for generations to come.
But that was an optical illusion. What Europeans took as a pristine blank page was in reality an active crime scene. Waves of colonial expeditioners, settlers and claims takers had seen to that, sweeping over the river basin in search of land and treasure. They brought the Bible, firearms and smallpox. Once thought to have numbered eight to 10 million, the Amazon population collapsed, falling by as much as 90 percent within a century of the European arrivals. The punishing tropical climate did the rest, making short work of cities raised on spongy soils, bereft of stone and built precariously of mud, wood, fiber and bone. The Amazon wasn't empty; it had metabolized its history.
It took the tools of 21st-century science—satellite imaging, laser detection, DNA testing, x-ray fluorescence soil scans and phytological analysis—to unveil the ancient human presence below the treetops. The global health emergency of the pandemic actually helped, throwing together a vast and eclectic scientific community, ranging from archeologists to plant geneticists, to quarrel and quiz one another in countless Zoom rooms. They emerged apostates, doubling down on the conviction that the Amazon, far from inhospitable, was once home to large, highly complex societies, who often lived behind battlements and palisades, interacted over long, even continental distances, and drew sustenance from fishing weirs and carefully managed forests.
One of the most vexing mysteries of the Amazon is how ancient communities flourished in a region known for its nutrient-poor and acid soils. Now we know from years of excavations and biochemical scans that the Amazon's pioneers made their own soil. By systematically discarding scraps of food, fishbones, thatch and charcoal from hearths, local populations composted their land, creating expansive patches of fecund "terra preta," or dark earth.
"It wasn't that early Amazonians set out to deliberately create their own fertilizer," Wenceslau Teixeira, a soil expert at the Brazilian agricultural research center, Embrapa, told Newsweek. "They were solving a waste management problem." In time, they saw their dump heaps turn dark and fertile, loaded with restorative elements such as phosphorous, calcium, zinc and manganese. Yesterday's refuse became tomorrow's garden. This was the circular economy millennia before the term existed.
Such prolific, if inadvertent, creation of so-called anthrosols (human-made soils) covering a patch of Amazonia bigger than Nepal, "may have played a pivotal role in enabling the development of ancient agricultural societies in the region," a multidisciplined research team including Teixeira concluded. Some Amazonian communities create dark earth to this day.
Dark earth is just one clue to how early Amazonians husbanded the rainforest. While the Amazon is home to some 16,000 tree species, a seminal study of 1,170 forest plots showed that half of them belonged to just 227 species, including important sources of food, fuel, building material and medicine. The recent LIDAR data has just bolstered that conclusion, flagging an abundance of 53 domesticated species near vestiges of engineered Amazonian earthworks.
"The Amazon is just like any other biome," said Charles Clement, a geneticist and leading Amazon scholar. "It was always a managed environment."
The lesson buried in the data clouds and biolabs is as simple as it is compelling. Understanding the way ancient Amazonians stewarded the standing forest not only helps set the historical record straight. It also offers a glimpse of how we might yet correct course and reimagine the marquee tropical biosphere not as a treasure chest, but perhaps the world's best hedge against the ravages of an increasingly rogue climate.
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