Beginning a little more than two thousand years ago, the central and lower Amazon were rocked by extreme cultural change. Arawak-speaking groups migrated in from the south and west, sometimes apparently driving Tupí-speaking groups north and east. Sedentary villages appeared. And so did terra preta. No one yet knows if or how these events were related. By about the time of Christ the central Amazon had at least some large, settled villages—Neves, Petersen, and Bartone excavated one on a high bank about thirty miles up the Río Negro. Judging by carbon dating and the sequence of ceramics, they believe the site was inhabited in two waves, from about 360 B.C., when terra preta formation began, to as late as 1440 A.D. “We haven’t finished working, but there seems to be a central plaza and some defensive ditches there,” Petersen told me. The plaza was at least a quarter mile long; the ditch, more than three hundred feet long and up to eighteen feet wide and six feet deep: “a big, permanent settlement.”
Terra preta showed up at the papaya plantation between 620 and 720 A.D. By that time it seems to have been underneath villages throughout the central Amazon. Several hundred years later it reached the upper Xingú, a long Amazon tributary with its headwaters deep in southern Brazil. People had lived around the Xingú for a long time, but around 1100 or 1200 A.D., Arawak-speaking people appear to have moved in, jostling shoulders with people who spoke a Tupí-Guaraní language. In 2003 Heckenberger, who had worked with Petersen and Neves, announced in Science that in this area he and his colleagues had turned up remains of nineteen large villages linked by a network of wide roads “in a remarkably elaborate regional plan.” Around these settlements, which were in place between approximately 1250 and 1400 A.D., the Xinguanos built “bridges, artificial river obstructions and ponds, raised causeways, canals, and other structures…a highly elaborate built environment, rivaling that of many contemporary complex societies of the Americas and elsewhere.” The earlier inhabitants left no trace of terra preta; the new villages quickly set down thick deposits of black earth. “To me,” Woods said, “it looks as if someone invented it, and the technique spread to the neighbors.”
Because Amazonia lacks stone and metal and its hot, wet climate rapidly destroys wood and cloth, material traces of past societies are hard to find. The main exception is pottery, striking examples of which survive, such as the highly decorative vessels from the Santarém area (right, this one probably made in the seventeenth century). Stone, being rare, was reserved for special items such as the pestles (left) used to grind the hallucinogenic snuff yobo.
One of the biggest patches of terra preta is on the high bluffs at the mouth of the Tapajós, near Santarém. First mapped in the 1960s by the late Wim Sombroek, director of the International Soil Reference and Information Center in Wageningen, the Netherlands, the terra preta zone is three miles long and half a mile wide, suggesting widespread human habitation—exactly what Orellana saw. The plateau has never been carefully excavated, but observations by geographers Woods and Joseph McCann of the New School in New York City indicate that it is thick with ceramics. If the agriculture practiced in the lower Tapajós were as intensive as in the most complex cultures in precontact North America, Woods told me, “you’d be talking something capable of supporting about 200,000 to 400,000 people”—making it at the time one of the most densely populated places in the world.
Woods was part of an international consortium of scientists studying terra preta. If its secrets could be unraveled, he said, it might improve the expanses of bad soil that cripple agriculture in Africa—a final gift from the peoples who brought us tomatoes, maize, manioc, and a thousand different ways of being human.
“Betty Meggers would just die if she heard me saying this,” Woods told me. “Deep down her fear is that this data will be misused.” In 2001, Meggers charged in an article in Latin American Antiquity that archaeologists’ claims that the Amazon could support intensive agriculture were effectively telling “developers [that they] are entitled to operate without restraint.” These researchers had thus become unwitting “accomplices in the accelerating pace of environmental degradation.” Centuries after the conquistadors, she lamented, “the myth of El Dorado is being revived by archaeologists.”
Doubtless her political anxieties are not without justification, although—as some of her sparring partners observed—it is difficult to imagine greedy plutocrats “perusing the pages of Latin American Antiquity before deciding to rev up the chainsaws.” But the new picture doesn’t automatically legitimate burning down the forest. Instead it suggests that for a long time clever people who knew tricks that we have yet to learn used big chunks of Amazonia nondestructively. Faced with an ecological problem, the Indians fixed it. Rather than adapt to Nature, they created it. They were in the midst of terra-forming the Amazon when Columbus showed up and ruined everything.
The Artificial Wilderness
A THOUSAND KUDZUS EVERYWHERE
Until about 200 million years ago Eurasia and the Americas were lashed together in a single landmass that geologists call Pangaea. Pangaea broke into pieces, sending the continents drifting like barges across the ocean floor. For millions of years, the separate fragments of Pangaea had almost no communication. Evolution set their species spinning off on separate trajectories, and the flora and fauna of each land diverged so far from each other that the astounded Columbus remarked that “all the trees were as different from ours as day from night, and so the fruits, the herbage, the rocks, and all things.”
Columbus was the first to see the yawning biological gap between Europe and the Americas. He was also one of the last to see it in pure form: his visit, as Alfred Crosby put it, initiated the process of knitting together the seams of Pangaea. Ever since 1492, the hemispheres have become more and more alike, as people mix the world’s organisms into a global stew. Thus bananas and coffee, two African crops, become the principal agricultural exports of Central America; maize and manioc, domesticated in Mesoamerica and Amazonia respectively, return the favor by becoming staples in tropical Africa. Meanwhile, plantations of rubber trees, an Amazon native, undulate across Malaysian hillsides; peppers and tomatoes from Mesoamerica form the culinary backbones of Thailand and Italy; Andean potatoes lead Ireland to feast and famine; and apples, native to the Middle East, appear in markets from Manaus to Manila to Manhattan. Back in 1972 Crosby invented a term for this biological ferment: the Columbian Exchange.
By knitting together the seams of Pangaea, Columbus set off an ecological explosion of a magnitude unseen since the Ice Ages. Some species were shocked into decline (most prominent among them Homo sapiens, which in the century and a half after Columbus lost a fifth of its number, mainly to disease). Others stumbled into new ecosystems and were transformed into environmental overlords: picture-book illustrations of what scientists call “ecological release.”
In ecological release, an organism escapes its home and parachutes into an ecosystem that has never encountered it before. The majority of such escapees die rapidly, unable to thrive or reproduce in novel surroundings. Most of the survivors find a quiet niche and settle in, blending inconspicuously with the locals. But a few, finding themselves in places with few or none of their natural enemies, look around with the hopeful incredulity of juvenile delinquents who discover the mall’s security cameras are broken—and wreak havoc. In their home ecosystems these species have, like all living things, a full complement of parasites, microbes, viruses, and insect predators to shorten and immiserate their lives. Suddenly free of this burden, they can burst out and overwhelm the landscape.
The Japanese grind the roots of a low vine called kuzu (Pueraria lobata) into a white powder that thickens soup and is alleged to have curative properties; they also plant the species on highway shoulders as erosion-preventing ground cover. In the 1930s the U.S. Civilian Conservation Corps planted millions of kuzu seedlings to fight soil loss, a major fear in the era of the Dust Bowl. Renamed “kudzu,” the vine prevented so much erosion that villages across the U.S. Southeast celebrate
d kudzu festivals and crowned kudzu queens. People harvested it like hay and fed it to cows; entrepreneurs marketed kudzu cereal, kudzu dog food, and kudzu ketchup. In the early 1950s rural areas suddenly awoke from their trance and discovered that kudzu was eating them alive. Without its natural enemies the plant grew so fast that southerners joked they had to close their windows at night to keep it out. Worse, the plants themselves grew bigger than is usual in Japan—nobody knows why. Engulfing fields in dense mats of root and vine, kudzu swarmed over entire farms, clambered for miles along telephone lines, wrapped up trees, barns, and houses like a green Christo. The roots sank so deep that the vine was nearly impossible to remove. In 1996 the federal government estimated that kudzu had swallowed seven million acres. The figure is now much larger.
What happened after Columbus was like a thousand kudzus everywhere. Throughout the hemisphere ecosystems cracked and heaved like winter ice. Echoes of the biological tumult resound through colonial manuscripts. Colonists in Jamestown broke off from complaining about their Indian neighbors to complain about the depredations of the rats they had accidentally imported. Not all the invaders were such obvious pests, though. Clover and bluegrass, in Europe as tame and respectable as accountants, in the Americas transformed themselves into biological Attilas, sweeping through vast areas so quickly that the first English colonists who pushed into Kentucky found both species waiting for them. Peaches, not usually regarded as a weed, proliferated in the southeast with such fervor that by the eighteenth century farmers feared that the Carolinas would become “a wilderness of peach trees.”
South America was hit especially hard. Endive and spinach escaped from colonial gardens and grew into impassable, six-foot thickets on the Peruvian coast; thousands of feet higher, mint overwhelmed Andean valleys. In the pampas of Argentina and Uruguay, the voyaging Charles Darwin discovered hundreds of square miles strangled by feral artichoke. “Over the undulating plains, where these great beds occur, nothing else can now live,” he observed. Wild peach was rampant in South America, too. Peachwood, Darwin discovered, had become “the main supply of firewood to the city of Buenos Ayres.” Some invasions cancel each other out. Peru’s plague of endive may have been checked by a simultaneous plague of rats, which the sixteenth-century writer Garcilaso de la Vega reported “bred in infinite numbers, overran the land, and destroyed the crops.”
A phenomenon much like ecological release can occur when a species suddenly loses its burden of predators. The advent of mechanized fishing in the 1920s drastically reduced the number of cod from the Gulf of Maine to the Grand Banks. With the cod gone, the sea urchins on which they fed had no enemies left. Soon a spiny carpet covered the bottom of the gulf. Sea urchins feed on kelp. As their populations boomed, they destroyed the area’s kelp beds, creating what icthyologists call a “sea urchin barrens.”
In this region, cod was the species that governed the overall composition of the ecosystem. The fish was, in ecological jargon, a “keystone” species: one “that affects the survival and abundance of many other species,” in the definition of Harvard biologist Edward O. Wilson. Keystone species have disproportionate impact on their ecosystems. Removing them, Wilson explained, “results in a relatively significant shift in the composition of the [ecological] community.”
Until Columbus, Indians were a keystone species in most of the hemisphere. Annually burning undergrowth, clearing and replanting forests, building canals and raising fields, hunting bison and netting salmon, growing maize, manioc, and the Eastern Agricultural Complex, Native Americans had been managing their environment for thousands of years. As Cahokia shows, they made mistakes. But by and large they modified their landscapes in stable, supple, resilient ways. Some milpa areas have been farmed for thousands of years—time in which farmers in Mesopotamia and North Africa and parts of India ruined their land. Even the wholesale transformation seen in places like Peru, where irrigated terraces cover huge areas, were exceptionally well done. But all of these efforts required close, continual oversight. In the sixteenth century, epidemics removed the boss.
American landscapes after 1492 were emptied—“widowed,” in the historian Francis Jennings’s term. Suddenly deregulated, ecosystems shook and sloshed like a cup of tea in an earthquake. Not only did invading endive and rats beset them, but native species, too, burst and blasted, freed from constraints by the disappearance of Native Americans. The forest that the first New England colonists thought was primeval and enduring was actually in the midst of violent change and demographic collapse. So catastrophic and irrevocable were the changes that it is tempting to think that almost nothing survived from the past. This is wrong: landscape and people remain, though greatly altered. And they have lessons to heed, both about the earth on which we all live, and about the mental frames we bring to it.
ONE OUT OF EVERY FOUR BIRDS
When passenger pigeons drank, they stuck their heads beneath the surface of the water until they were eye deep. When they walked, their heads bobbed awkwardly and they looked around from side to side. Passenger pigeons were greedy eaters with terrible manners; if they found some food they liked just after finishing a meal, they would vomit what they had previously eaten and dig in. Gobbling their chow, they sometimes twittered in tones musical enough that people mistook them for little girls. They gorged on so many beechnuts and acorns that they sometimes fell off their perches and burst apart when they hit the ground. But in flight they were angelic: they cut through the air with such speed and grace that they were called “blue meteors.”
When passenger pigeons found an area with grain or nuts to eat, they formed a long, linear front that advanced forward, heads peck-peck-pecking at the ground. Acorns, beechnuts, and chestnuts; strawberries, huckleberries, and blackberries; wheat, oats, and maize—all went down the pigeons’ iridescently feathered gullets. To grab their share, the pigeons at the rear constantly fluttered over the heads of their compatriots and landed at the leading edge of the front. Then the birds in the back flew over them. The line of birds advanced in a continuous swirl, the conservationist John Muir recalled, “revolving something like a wheel with a low buzzing wing roar that could be heard a long way off.”
Passenger pigeons traveled in massive assemblies, billions strong, that rained enough excrement to force people indoors. As a boy Muir saw a mob of birds sweep “thousands of acres perfectly clean of acorns in a few minutes.” Pigeons destroyed farm fields so often that the bishop of Quebec formally excommunicated the species in 1703. A hundred and ten years later the artist and naturalist John J. Audubon saw a flock passing overhead in a single cloud for three whole days. “The air,” Audubon wrote later, “was literally filled with Pigeons; the light of noon-day was obscured as by an eclipse.” When he visited their roost, the “dung lay almost two inches deep” for miles.
The Pigeons, arriving by thousands, alighted everywhere, one above another, until solid masses as large as hogsheads were formed on the branches all round. Here and there the perches gave way under the weight with a crash, and, falling to the ground, destroyed hundreds of the birds beneath, forcing down the dense groups with which every stick was loaded. It was a scene of uproar and confusion. I found it quite useless to speak [over the roar of wings], or even to shout to those persons who were nearest to me.
According to Arlie W. Schorger, author of a definitive study on the bird, in Audubon’s day at least one out of every four birds in North America was a passenger pigeon.
In colonial times, the Haudenosaunee celebrated pigeon roostings by gathering around the birds for a massive feast. Horatio Jones, captured as a teenager by the Seneca (one of the six nations in the alliance), participated around 1782 in a mass pigeon hunt near the Genesee River. The birds, roosting on low branches, were too full and too stupid to flee. Men knocked them down with poles or toppled the trees they were sitting on. Children wrung the birds’ necks while women stewed them in pots, smoked them over fires, and dried them to preserve in storehouses. Sometimes the Seneca at
e half a dozen squabs at a time, necks tied together in a carnivorous sculpture. “It was a festival season,” Jones later recalled. “Even the meanest dog in camp had his fill of pigeon meat.” In Haudenosaunee lore, the birds represented nature’s generosity, a species literally selected by the spirit world to nourish humankind.
Non-Indians, too, saw the pigeon as a symbol of the earth’s richness—“the living, pulsing, throbbing, and picturesque illustration of the abundance of food, prepared by bountiful Nature, in all her supreme ecstasy of redundant production of life and energy,” one businessman/pigeon enthusiast gushed. Colonists grilled the birds, stewed them with salt pork, and baked them into pies; they plucked their feathers to stuff mattresses, pickled them in barrels as a winter treat, and fed them to livestock. Incredibly, hunters in the countryside captured tens of thousands of pigeons in nets and sent the living birds to urban hunting clubs for target practice.
Then, suddenly, the passenger pigeon vanished—the last bird, Martha, named after Martha Washington, died on September 1, 1914. The passenger pigeon remained an emblem of natural bounty, but now it also represented the squandering of that bounty. In 1947 the conservationist Aldo Leopold dedicated a monument to the pigeon near the site of its greatest recorded nesting, at which hunters slaughtered 1.5 million birds. The plaque read: “This species became extinct through the avarice and thoughtlessness of man.”
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