Guano mania took hold. In 1841, Britain imported 1,880 tons of Peruvian guano, almost all of it from the Chincha Islands; in 1843, 4,056 tons; in 1845, 219,764 tons. In forty years, Peru exported about 14 million tons of guano, receiving for it approximately £150 million, roughly $13 billion in today’s dollars. It was the beginning of today’s input-intensive agriculture—the practice of transferring huge amounts of crop nutrients from one place to another, distant place according to plans dictated by scientific research.
Hoping to take maximum advantage of the guano rush, Peru nationalized the Chinchas. Soon it discovered that nobody wanted to work on the islands. Except for birds, their only inhabitants were bats, scorpions, spiders, ticks, and biting flies. Not a single plant grew on their barren slopes. Worse, the islands had no water; every drop had to be shipped in. Because the land was blanketed in guano, miners worked, ate, and slept on shelves of ancient excrement. So little rain fell that the soluble materials in the guano never washed away—it remained studded with crystals of ammonia, which broke in corrosive clouds around miners’ shovels. Powdery and acrid, the guano went into miners’ carts, which were pushed up rails to a depot atop one of the seaside cliffs. From the cliff, men dumped tons of excrement through a long canvas tube directly into the bellies of vessels below. Slamming into the hold, guano dust exploded from the hatchways, shrouding the ship in a toxic fog. Workers wore masks made from hemp smeared with tar, one visitor noted,
but the guano mocks at such weak defenses.… [T]hey are unable to remain below longer than twenty minutes at one time. They are then relieved by another party, and return on deck perfectly naked, streaming with perspiration, and with their brown skins thickly coated with guano.
The government could have paid high wages to get workers to endure these terrible conditions, but that would have cut into profits. Instead it stocked the islands with a mix of convicts, army deserters, and African slaves. This arrangement proved unsatisfactory: the convicts and deserters killed each other, and the slaves were so valuable that their mainland owners did not wish to part with them. In 1849 Peru gave up trying to run the mines itself and awarded an exclusive concession to Domingo Elías, Peru’s biggest cotton grower and one of its principal slave owners. Politically savvy and manically ambitious, Elías had been prefect of Lima; during a time of civil unrest, he briefly declared himself ruler of the nation. In return for the monopoly, Elías was supposed to mine guano with his own slaves, but he, too, was reluctant to take them away from his cotton fields. He induced the government to subsidize merchants who imported immigrants. Prominent among these subsidized importers was Domingo Elías. By the time the law passed his agents were already in Fujian, waving labor contracts in the faces of illiterate villagers.
Thousands of Chinese slaves mined the guano of Peru’s Chincha Islands, shown here in 1865, for export to Europe as fertilizer. The islands, home for millennia to seabirds, were covered with a layer of guano as much as 150 feet deep. (Photo credit 6.4)
In standard indenture practice, the contracts promised the Chinese would pay for their passage by working, typically for eight years, in the newly discovered California gold fields. (The actual destination, the guano archipelago, was not mentioned.) The ruse was plausible: agents for U.S. firms were in Fujian at the same time, telling a similar lie as they sought indentured servants to build railroads. People who signed the bogus Peruvian contract were conducted to bleak human warehouses in Amoy (now called Xiamen, on an island across the river from Yuegang) and, later, Macao. People who refused to sign often were kidnapped and shipped to the same warehouses. In these dark confines slavers burned the letter C—for California, their ostensible destination—into the backs of their ears. No longer were the men described as workers. Their new name was zhuzai, little pigs. “None were let outside,” wrote the Shanghai historian Wu Ruozeng. “Those who resisted were whipped; any who tried to escape were killed.”
Peru was not the only destination in the mid-century Chinese diaspora. A quarter of a million or more zhuzai, almost all of them men, ended up—more or less willingly, more or less knowingly—in Brazil, the Caribbean, and the United States. But Peru represented the longest passage, the worst conditions, the most dreaded destination. Ultimately at least 100,000 Chinese were taken there. Conditions en route can be compared to those in the transatlantic slave trade. Perhaps one out of eight zhuzai died. As on the Atlantic slave ships, revolts were common. Eleven mutinies are known to have occurred on Peru-bound vessels; at least five bloodily succeeded.
Most of the Chinese ended up working in the sugar and cotton plantations on the coast. Some built the railroads that the Peruvian government was constructing with guano money. At any given time between one and two thousand were on the Chincha Islands. In classic divide-and-conquer fashion, Elías forestalled rebellion by setting his African slaves as overseers over his Chinese slaves and holding both to strict deadlines. Spasms of cruelty, slave upon slave, were the inevitable result. Guano miners swung their picks up to twenty hours a day, seven days a week, to fulfill their assigned daily quotas (as much as five tons of guano); two-thirds of their pay was deducted for room (reed huts) and board (a cup of maize and some bananas). Failure to meet the daily quota was rewarded with a five-foot rawhide whip. Minor infractions were punished by torture. Escape from the islands was impossible. Suicide was frequent. One overseer told a New York Times correspondent that
more than sixty had killed themselves during the year,…chiefly by throwing themselves from the cliffs. They are buried, as they live, like so many dogs. I saw one who had been drowned—it was not known whether accidentally or not—lying on the guano, when I first went ashore. All the morning, his dead body lay in the sun; in the afternoon, they had covered it a few inches, and there it lies, along with many similar heaps, within a few yards of where they were digging.
So many Chinese died that the overseers marked off an acre of guano as a cemetery.
Journalistic exposés of guano slavery created an international scandal that gave the Lima government an excuse to eject Elías and renegotiate the guano contract with someone else, thus procuring a second round of bribes. Fulminating against the evils of official corruption, Elías sought to regain his lucrative concession by twice staging a coup d’état. Both attempts failed. In 1857 he tried the legal route, running for president without success.
All the while guano flowed to Europe and North America. In addition to signing an exclusive mining concession with Elías, Peru had awarded a monopoly on shipping guano internationally to a company in Liverpool. With demand outstripping supply, Peru and its British consignees were able to charge high prices. Their customers reacted with fury to what they viewed as extortion. Decrying the “powerful monopoly” on guano, the British Farmer’s Magazine laid out its readers’ demands in 1854. “We do not get anything like the quantity we require; we want a great deal more; but at the same time, we want it at a lower price.” If Peru insisted on getting a lot of money for a valuable product, the only fair solution was invasion. Seize the guano islands!
From today’s perspective, the outrage—threats of legal action, whispers of war, editorials about the Guano Question—is hard to understand. But agriculture was then “the central economic activity of every nation,” as the environmental historian Shawn William Miller has pointed out. “A nation’s fertility, which was set by the soil’s natural bounds, inevitably shaped national economic success.” In just a few years, agriculture in Europe and the United States had become dependent on high-intensity fertilizer—a dependency that has not been shaken since. Britain, first to adopt guano and by far the largest user, was both the most dependent and the most resentful. Much as oil buyers today begrudge the member nations of OPEC, Peru’s British customers ranted about the guano cartel. They were apoplectic as Peru’s guano barons sauntered around Lima in the latest Parisian fashions, bejeweled trollops on their arms.
Britons were almost entirely silent about Peru’s British agents in Liverpo
ol, who used their share of the Peruvian monopoly profits to construct one of the biggest houses in England. Americans were not silent. They fumed as the British gave priority to their British customers, leaving Americans at the end of the guano line. Spurred by their fury, Congress passed the Guano Islands Act in 1856, authorizing its citizens to seize any guano islands they saw. The biggest loads came from Navassa, an island fifty miles south of Haiti, which the United States took in 1857. After the Civil War its workforce consisted largely of freed slaves. Conditions gradually deteriorated; the former slaves rebelled twice, killing some of their jailers, and the enterprise fell apart in a cloud of scandal. Under the aegis of the Guano Islands Act, merchants claimed title to ninety-four islands, cays, coral heads, and atolls between 1856 and 1903. The Department of State officially recognized sixty-six as U.S. possessions. Most proved to have little guano and were quickly abandoned. Nine remain under U.S. control today.
Guano set the template for modern agriculture. Ever since Liebig, farmers have treated the land as a medium into which they dump bags of chemical nutrients. The nutrients are shipped from far-off places or synthesized in distant factories. Farming is the act of transferring those external nutrients to crops in the field: high volumes of nitrogen go in, high volumes of maize and potatoes go out. Because the harvests in this system are enormous, the crops are no longer vehicles for local subsistence, but products destined for an international market. To maximize output, they are grown in ever-larger, single-crop fields—industrial monoculture, as it is called.
Today scholars often describe the “Green Revolution” after the Second World War—the combination of high-yield crops, agricultural chemicals, and intensive irrigation—as the moment when humankind triumphantly escaped, at least for a while, the limits set by small-scale farms and local resources. But as the Amherst College historian Edward D. Melillo has argued, the arrival of guano ships in Europe and the United States marked an earlier, equally profound Green Revolution, the first in a series of technological innovations that transformed life across the planet.
Before the potato and maize, before intensive fertilization, European living standards were roughly equivalent with those today in Cameroon and Bangladesh; they were below Bolivia or Zimbabwe. On average, European peasants ate less per day than hunting-and-gathering societies in Africa or the Amazon. Industrial monoculture with improved crops and high-intensity fertilizer allowed billions of people—Europe first, and then much of the rest of the world—to escape the Malthusian trap.5 Incredibly, living standards doubled or tripled worldwide even as the planet’s population climbed from fewer than 1 billion in 1700 to about 7 billion today.
Along the way guano was almost entirely replaced by nitrates mined from vast deposits in the Chilean desert. The nitrates in turn were replaced by artificial fertilizers, made in factories by a process invented and commercialized in the early twentieth century by two Nobel-winning German chemists, Fritz Haber and Carl Bosch. No matter what their composition, though, fertilizers remain just as critical to agriculture, and through agriculture to contemporary life. In a fascinating 2001 study of the impact of factory-made nitrogen, Vaclav Smil, the University of Manitoba geographer, estimated that two out of every five people on earth would not be alive without it.
By any measure these were amazing accomplishments. Yet like all human endeavors the rise of intensive agriculture had its downside. The guano trade that launched modern agriculture was also the beginning, via the Columbian Exchange, of one of its worst pitfalls: the intercontinental transport of exotic pests. Proof will never be found, but it is widely believed that the guano ships carried a microscopic hitchhiker: Phytophthora infestans. P. infestans causes late blight, a plant disease that exploded through Europe’s potato fields in the 1840s, killing as many as two million people, half of them in Ireland, in what came to be known as the Great Hunger.
THOROUGHLY MODERN FAMINE
The name Phytophthora infestans means, more or less, “vexing plant destroyer,” a censure that is wholly deserved. P. infestans is an oomycete, one of seven hundred or so species sometimes known as water molds. From a biologist’s point of view, oomycetes can be thought of as cousins to algae. From a gardener’s point of view, P. infestans looks and acts like a fungus. It sends out tiny bags of six to twelve spores that are blown on the wind, usually for no more than twenty feet, occasionally for as much as half a mile or even further. When the bag lands on a susceptible plant, it hatches, so to speak, releasing what are technically known as zoospores: mobile, two-tailed cells that slowly swim through moisture on the leaf or stem, looking for the tiny respiratory holes called stomata. If the day is warm and wet enough, the zoospores germinate, sending long, threadlike filaments through the stomata into the leaf. Extensions from the filaments infiltrate leaf cells, hijacking the mechanisms inside; the plant ends up nourishing the invader, rather than itself. The first obvious symptoms—purple-black or -brown spots on the leaves—are visible in about five days. By that time it is often too late. Filaments lace through much of the plant. The oomycete is already generating new bags of spores.
Water is the blight’s friend—zoospores cannot germinate on dry leaves. Rain washes zoospores from the leaves onto the soil, letting them attack roots and tubers as much as six inches below the surface. Especially vulnerable are the tuber’s eyes. P. infestans strikes from the outside in, turning the potato’s outer flesh into dry, grainy, red-brown rot. Extensions of blight reach like dark claws toward the center of the tuber. Because the boundary between diseased and healthy tissue is indistinct, the entire potato must usually be thrown away. Care must be taken with disposal: a single infected tuber can generate a million spores.
P. infestans preys on members of the nightshade family: potatoes, tomatoes, eggplants, sweet peppers, and weeds like hairy nightshade and bittersweet nightshade. When shocked European researchers first observed the carnage in potato fields, they naturally assumed the agent responsible came from Peru, the land of potatoes. Seventy years ago most changed their minds. Typically biologists view a species’s “center of diversity”—the place where it has the widest array of forms—as its ancestral home. Mexico has hundreds of varieties of maize seen nowhere else, suggesting that the species originated there. Africans are more genetically diverse than Caucasians or Asians; Africa is the cradle of humankind. And so on. In central Mexico, P. infestans seemed more varied than anywhere else. Notably, the species occurs in two types—one could think of them as male and female, except that oomycetes have no sexual characteristics—that can combine their DNA, creating an egg-like entity known as an oospore. In other words, P. infestans can reproduce both asexually and “sexually,” with the quotation marks as a reminder that these creatures are not male and female.6 But only in Mexico did the oomycete reproduce sexually, because the rest of the world lacked one of the two forms. Scientists argued that this and other types of diversity indicated that P. infestans originated in Mexico—even though there is no evidence of S. tuberosum there until the eighteenth century. Alexander von Humboldt, visiting Mexico in 1803 with his samples of guano, made the first certain observation of a potato in Mexico. Humboldt assumed that Spaniards had imported the tuber from the Andes. The potato blight had existed for millennia, in this view, before it encountered a potato. A final detail: because blight was spotted in the United States before Europe, some researchers suggested that it spread there first, then hopped a boat across the Atlantic.
In a series of experiments culminating in 2007, a team led by University of North Carolina plant geneticist Jean Ristaino overturned these ideas. Ristaino’s team used the tools of DNA analysis to examine blight from 186 infected potatoes in herbariums, the botanical storehouses in museums. The youngest sample was from 1967; three were collected in Europe in 1845–47, the time of the Great Hunger. Ristaino’s scheme was complex in detail, but simple in principle. Because P. infestans usually reproduces asexually, the progenitor oomycete and its offspring usually have identical genetical
endowments, except for the infrequent occasions when a mutation scrambles DNA. Organisms with similar DNA patterns belong, as geneticists say, to the same “haplogroup.” If two individuals belong to the same haplogroup, it is molecular evidence that they share a recent ancestor. Similarly, different haplogroups are a sign of the lack of a recent common ancestor. Ristaino’s team found that potato blight from the Andes had a greater number of haplogroups than Mexican blight—it was fundamentally more diverse. Moreover, DNA from the old blight in herbariums—samples preserved for as long as a century and a half—was nearly identical to DNA from Andean blight. “The U.S. and Irish populations were not genetically differentiated from the Peruvian populations,” the scientists wrote. Blight from the Andes “initiated epidemics first in the U.S. and then Ireland that led to the famine.”
Most likely the blight traveled from Peru to Europe aboard a guano ship to Belgium, probably to Antwerp, the area’s most important port. Farmers in the adjacent province of West Flanders were having trouble with their potatoes. In what would now be described as a demonstration of the power of evolution, European plant pathogens—viruses and fungi—were adapting to the new crop. In July 1843 the provincial council of West Flanders voted to import new varieties of potato from North and South America, hoping some would prove to be less susceptible to the diseases. No record exists of their origins or the means by which they were shipped. It would be odd, though, if the South American potatoes had not come from the Andes.