Painted Rock Cave was occupied at roughly the same time that the Clovis culture was thriving to the north. But Amazon paleo-Indians didn’t live in the same way as their northern counterparts, Roosevelt said. They didn’t make or use Clovis points. They didn’t hunt big game (almost none exists in the Amazon). Instead they plucked wild fruits from the forest, painted handprints on the walls, and ate the Amazon’s 1,500 species of fish, especially the 500-pound piraruçu, the world’s biggest freshwater fish. And then, after 1,200 years, these early people left the cave for good.
Painted Rock Cave became inhabited again in about 6000 B.C. Probably it was no more than temporary shelter, a refuge when floodwaters got too high. People could have brought in loads of turtles and shellfish, built a fire in the shelter of the cave, and enjoyed the feel of dry land. In any case these people—Roosevelt called them the Paituna culture, after a nearby village—had ceramic bowls, red- to gray-brown. Found at Painted Rock Cave and other places in the area, it is the oldest known pottery in the Americas.
And so there were two occupations: one very old, with ceramics; the other even older, without them. To Roosevelt, the first settlement of Painted Rock Cave demonstrated that the Amazon forest was not settled by a copy or offshoot of Clovis. This early culture was a separate entity—another nail in the coffin of the Clovis-as-template theory, to her way of thinking. The second occupation, with its early and apparently independent development of ceramics, demonstrated something equally vital: Amazonia was not a dead end where the environment ineluctably strangled cultures in their cradles. It was a source of social and technological innovation of continental importance.
By about four thousand years ago the Indians of the lower Amazon were growing crops—at least 138 of them, according to a recent tally. The staple then as now was manioc (or cassava, as it is sometimes called), a hefty root that Brazilians roast, chop, fry, ferment, and grind into an amazing variety of foods. To this day, no riverside table is complete without a bowl of farofa: crunchy, toasted manioc meal, vaguely resembling grated Parmesan cheese, which Amazonians sprinkle on their food with abandon. To farmers, manioc has a wonderful advantage: it can grow practically anywhere, in any conditions. In Santarém I met a woman who told me that the asphalt street in front of her home had just been ripped up by the municipal authorities. Underneath the pavement, which had been laid down years before, was a crop of manioc.
Manioc has always been the Amazonian staple. To this day, it is ubiquitous in the slash-and-burn plots that surround every riverside hamlet. These little, shifting farms look like unchanged remnants of the past. But that idea apparently is mistaken. Rather than being the timeless indigenous adaptation portrayed in ecology textbooks, many archaeologists now view slash-and-burn agriculture as a relatively modern technique whose spread was driven by European technology. The main reason is the stone ax.
Living in the world’s thickest forest, the inhabitants of the Amazon basin had to remove a lot of trees if they wanted to accomplish practically anything. For this task the stone ax was their basic tool. Unfortunately, stone axes are truly wretched tools. With a stone ax, one does not so much cut down a tree as use the ax to beat a section of the trunk to pulp, weakening the base until the tree can no longer support itself. In the outskirts of the central Amazonian city of Manaus, a researcher let me whack at a big Brazil nut tree with a locally made replica of a traditional stone ax. After repeated blows I had created a tiny dent in the cylindrical wall of the bole. It was like attacking a continent. “Those things suck,” the researcher said, shaking his head.
In the 1970s Robert Carneiro, of the American Museum of Natural History, estimated the labor required to clear a field before the advent of steel. He watched Yanomamö work with stone and steel axes and on the basis of these observations came up with a formula to project the time necessary to cut individual trees with both types of tool. The difference was striking. Felling a single four-foot tree with an indigenous stone axe would take 115 hours—nearly three weeks of eight-hour days. With a steel axe, workers could topple the same tree in less than three hours. Stone axes would clear an acre and a half, a typical slash-and-burn plot, in the equivalent of 153 eight-hour days. Steel axes would do the job in the equivalent of eight workdays—almost twenty times faster. According to surveys by Stephen Beckerman, an anthropologist at Pennsylvania State University, Amazonian slash-and-burners are able to work their plots for an average of three years before they are overwhelmed. Given that farmers also must hunt, forage, build houses and trails, maintain their existing gardens, and perform a hundred other tasks, Carneiro wondered how they could have been able to spend months on end banging on trees to clear new fields every three years.
Unsurprisingly, people with stone implements wanted metal tools as soon as they encountered them—the prospective reduction in workload was staggering. When Columbus landed, according to William Balée, the Yanomamo lived in settled villages in the Amazon basin. Battered by European diseases and slave raiding, many fled to the Orinoco, becoming wandering foragers. In the seventeenth century they acquired steel tools, and used them to make the return journey from seminomadic hunter-gatherers to agriculturalists who lived in more or less permanent villages. So precious did European axes become during this time, according to Brian Ferguson, an anthropologist at Rutgers University, that when a source appeared the Yanomami would relocate whole villages to be near it. Steel tools, he told me, “had a major, transformative effect on all the trade and marriage relations in a whole area. They led to new trade networks, they led to new political alliances, they even led to war.” Researchers have often described the Yanomamo as “fierce,” aggressive sorts whose small villages are constantly at violent odds with one another. In Ferguson’s estimation, one cause of the endemic conflict observed by Western anthropologists and missionaries was the anthropologists and missionaries themselves, who gave their subjects “literally boatloads” of steel tools—axes, hatchets, machetes—to ingratiate themselves. At a stroke, the village hosting the Westerners would gleam with wealth; its neighbors would seek a share of the undeserved bounty; conflict would explode. “Steel to the Yanomamo was like gold for the Spanish,” Ferguson said. “It could push fairly ordinary people to do things that they wouldn’t consider doing otherwise.” (The anthropologists and missionaries there vehemently deny Ferguson’s claims. But so far as I am aware they did not call his scenario impossible. Rather, they said that to avoid unhappy consequences they had carefully controlled the amount of gift giving.)
Metal tools largely created slash-and-burn agriculture, William M. Denevan, the Wisconsin geographer, told me. “This picture of swidden as this ancient practice by which Indians kept themselves in a timeless balance with Nature—that is mostly or entirely a myth, I think. At least there’s no evidence for it, and a fair amount of evidence against it, including the evidence of simple logic.” Slash-and-burn, supposedly a quintessentially Amazonian trait, “is a modern intrusion.”
A similar phenomenon seems to have taken place in North America, where Indians were widely said to have practiced slash-and-burn as part of their habit of living lightly on the land. Dismissing the data to back up these claims as “gossamer,” the geographer William E. Doolittle of the University of Texas noted in 2000 that most colonial accounts showed Indians clearing their fields permanently, even ripping stumps out to prevent them from sprouting. “Once fields were cleared, the intent was to cultivate them permanently, or at least for very long periods of time.” As populations rose, “farmers cleared new fields from the remaining forests.” Slash-and-burn was a product of European axes—and European diseases, which so shrank Indian groups that they adopted this less laborious but also less productive method of agriculture.
In the Amazon, the turn to swidden was unfortunate. Slash-and-burn cultivation has become one of the driving forces behind the loss of tropical forest. Although swidden does permit the forest to regrow, it is wildly inefficient and environmentally unsound. The burning se
nds up in smoke most of the nutrients in the vegetation—almost all of the nitrogen and half the phosphorus and potassium. At the same time, it pours huge amounts of carbon dioxide into the air, a factor in global warming. (Large cattle ranches are the major offenders in the Amazon, but small-scale farmers are responsible for up to a third of the clearing.) Fortunately, it is a relatively new practice, which means it has not yet had much time to cause damage. More important, the very existence of so much healthy forest after twelve thousand years of use by large populations suggests that whatever Indians did before swidden must have been ecologically more sustainable.
IN THE WEST
In 1977 a Brazilian geography student named Alceu Ranzi got a summer job with the National Program of Archaeological Research in the Amazon Basin. Dubbed PRONAPABA, its Portuguese acronym, the Smithsonian-sponsored program was conducting the first-ever full archaeological survey of Amazonia, which was being logged for cattle ranches at a speed that was beginning to cause protests. To Ranzi’s surprise, in his home state of Acre—Brazil’s westernmost region, a ranching center—PRONAPABA discovered half a dozen large circular ditches carved into the newly cleared land.
PRONAPABA did not formally announce its finding for eleven years, and even then only in an obscure, un-refereed journal. Meanwhile Ranzi went on to become a well-respected paleontologist, most recently at the Federal University of Acre, in Rio Branco. On a flight to Acre in 1999, he casually looked out the window at some recently opened land. In clear view was a geometric figure carved into the earth—he had spotted the earthworks again. Recalling his previous work, he began looking for more, driving around ranches, cadging rides in private planes. Within a year, he told me, “we had found dozens.” Shaped like circles, diamonds, hexagons, and interlocking rectangles, the earthworks are three to nine hundred feet in diameter and outlined by trenches up to twenty feet deep.
Despite their size, Ranzi had trouble getting people to pay attention. Acre is in the western Amazon, on Bolivia’s northern border, the hinterlands of the hinterlands. The highway from the center of the country is impassable for as much as half the year. Plane flights are infrequent and long. A lot of people travel around the state by boat, on the many tributaries of the Amazon. To outsiders, the state is best-known for being the home of legendary rubber-tapper, union organizer, and anti-deforestation activist Chico Mendes, who was murdered there in 1988; the state’s main forest reserve is named after him. To many Brazilians, Acre seems scarcely less remote—when I first visited, a friend in Rio de Janeiro could hardly believe I was going there. Nonetheless, Ranzi kept contacting anyone he thought could help him find out more about the earthworks. To help attract attention, he called them by a catchy name: geoglyphs. Eventually, researchers came to Acre. By 2005 Ranzi was co-leading a research team with Martti Pärssinen of the University of Helsinki and Denise Schaan of the Goeldi Museum in Belém, near the mouth of the Amazon.
Six years later, the tally of geoglyphs in Acre alone had grown to more than two hundred. Scores or even hundreds more, the geoglyphs team said, remain to be found in Acre, the neighboring state of Rondônia, and the adjacent Bolivian department of Pando. During one of my trips to the area, Ranzi wangled a flight for Schaan, himself, and me on a military helicopter; the overflight, which lasted little more than an hour, was enough to discover three more. (The photograph in the first chapter of this book was taken on that flight.)
The purpose of the geoglyphs remains unknown. Nonetheless, Schaan told me, their location and size is enough to make them “very difficult to fit in with what we thought in the past.” Most known geoglyphs are located not near the floodplains but on higher ground. Schaan and Ranzi have estimated that building a single geoglyph 600 feet across would require moving ten thousand cubic yards of earth—a big task without metal tools. Given the labor required for construction and the large number of earthworks, the geoglyphs team has argued that the Acre uplands must have been inhabited “for hundreds of years” by “sizable, regionally organized populations.”
In some sense, the geoglyphs shouldn’t be there. The long-lasting, crowded populations suggested in Acre are exactly the sort that archaeologists long thought were ecologically impossible. Moreover, they were located not in the floodplains, where the meager soils are replenished by silt and people can fish for proteins, but the uplands, which have so few resources that researchers long believed they were unfit for prolonged habitation. Partly because of these arguments, many ecologists have thought that the uplands—more than 90 percent of the Amazon basin—must consist of untouched primary forest and savannah, a landscape never painted by the human brush. The geoglyphs suggest something else. Because they cannot be seen through thick forest, researchers believe they must have been constructed at a time when the region had little tree cover. In other words, the great forests of the western Amazon may have looked considerably different in the not too distant past.
The geoglyphs are only part of the puzzle. As archaeologists have recently learned, the first inhabitants of the western Amazon created a swath of earthworks that stretches between the Beni in southeastern Bolivia and Acre in western Brazil—a seven-hundred mile swath of raised fields; canal-like water channels; tall settlement mounds; circular pools; permanent, zigzag fish weirs; mile-long, raised causeways; and hundreds of earthworks, ranging from simple, irregular ditches in the south to elaborate geometric arrays in the north. According to Clark Erickson, the University of Pennsylvania researcher who invited me to the Beni, the region is a laboratory for historical ecology—a model of how human beings can use even the most apparently unpromising areas to create and maintain environments that match their needs.
Traditionally, archaeologists have regarded the wet tropics as unpromising. Because Amazonia has little stone or metal, “99 percent of material culture was perishable,” Erickson told me. “Cane, chonta [palm wood], bones, basketry, wood—none of it survives these conditions. The whole culture, even if it was there for thousands of years, seems to be gone.” In consequence, he said, archaeologists in the Amazon have been forced to adopt other methods, from soil chemistry to network theory. Instead of working from individual sites, as is traditional archaeological practice, researchers must study entire landscapes.
The Beni, where Erickson and his Bolivian colleagues have focused their efforts, is an example. Exceptionally low and flat, much of the department is covered for up to four months of the year by a slowly moving wash of water—snowmelt from the Andes and heavy local rainfall—that is as much as three feet deep. During the dry season the water evaporates and the Beni becomes a hot, arid savanna, kept open by annual burning. To avoid the annual flood, Indians lived on slightly raised forested “islands.” In the lowest parts of the department, the “islands” weren’t high enough, so people constructed thousands of mounds as dwelling places. Most of the mounds were small—their summits barely top the water—but a few were 30 or even 60 feet tall. Some are still inhabited by Indian groups.
Living on this artificial inland archipelago, native peoples ate a diet heavy in fish, which migrate and spawn in the flooded savannas. Crisscrossing the savanna are networks of earthen fish weirs: interconnected low berms that change direction, zigzag-style, every thirty to a hundred feet. At the angles are funnel-like openings for nets or basket traps. When the waters receded, the area’s original inhabitants ensured that the fish drained into hundreds of artificial fish ponds. Some are still full of fish today.
Agriculture was just as intensive. In a broad reach of savanna, the Beni’s original inhabitants built raised fields—artificial platforms of soil that lift crops above the floodwaters. Like the raised beds in temperate-zone gardens, they promote drainage and increase the amount of topsoil available to plants. The few carbon dates available suggest that the fields date from about three thousand years ago to about five hundred years ago—roughly the time the conquistadors arrived, bringing European diseases. “Like any agricultural fields, these were not used forever,” Erickson to
ld me. “They went in and out of production, which suggests to me that we are looking at a long-term but dynamic system.” Because the mounds, weirs, and fields required enormous labor to construct and maintain, Erickson argued that these societies must have had large populations—“tens or even hundreds of thousands of people.”
To move people and goods from place to place, Indians built networks of ruler-straight causeways and canals, some of them three miles long. Puzzlingly, the causeways and canals are not present in every area. “Are they here just because it’s wetter in this place and so causeways and canals are needed?” Erickson asks. “Why do some people live in the swamp and savanna but use the causeways, and others live on mounds but appear to have no causeways in or out?” Even when Indians built causeways, not all mounds are connected to each other, a fact Erickson was hoping to use to decipher the relations between groups. To make sense of the pattern, he and a student—a Wall Streeter who was taking time away from the market to pursue his academic dreams—were trying to apply the techniques of network analysis to search for particularly important nodes in the networks of causeways, canals, mounds, and fields. Initial results showed a few key raised “islands” in control of a vast network of communication and interaction covering 200 square miles, as large as many early states.
Even as archaeologists try to work out how the area’s first inhabitants reshaped their physical environment, other scientists are beginning to trace out their impacts in its genetic heritage. According Charles R. Clement, a botanist at Brazil’s National Institute for Amazon Research in Manaus, the western Amazon was a center for plant domestication—a “Vavilov center,” as botanists call them. (The name comes from pioneering Soviet botanist Nikolai Vavilov, who first noted that plant domestication was concentrated into half a dozen small areas around the planet.) Agricultural geneticists have long accepted that the western Amazon was the development ground for peanuts, Brazilian broad beans (Canavalia plagiosperma), and two species of chili pepper (Capsicum baccatum and C. pubescens). But the list is much longer than that, according to Susanna Hecht, a UCLA geographer who has worked in the region for 30 years. “I would add rubber [made from the sap of Hevea brasiliensis] to the list,” she told me. Used for countless purposes by pre-Columbian populations, “it is at least a semi-domesticate, and it was clearly distributed by humans.” Still more important, in her view, was manioc (Manihot esculenta).