How Have Sweet Potatoes, Potatoes, and Maize Changed China?
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Over 500 years ago, the introduction of American crops not only revolutionized the Chinese diet, but also greatly contributed to the growth of the Chinese population.
Charles C. Mann. 1493: Uncovering the New World Columbus Created. Knopf.
Since the lockdown in Shanghai, getting food has become the focus of life. In this sense, we are no different from our Homo sapiens ancestors who gathered and hunted. Although we live in the 21st century with mobile Internet connectivity, more than 90% of our food calories come from a handful plants domesticated by our ancestors between 9500 and 3500 BC: wheat, rice, maize, potatoes, millet and barley.
Every day, I "hunt" for food from various WeChat purchase groups, grocery shopping apps and neighborhood committees. Fruits and leafy greens have become a luxury, and the most available in the fridge are potatoes and tomatoes, so much so that people are racking their brains to figure out how to make dishes out of a few vegetables they have.
This week I am still reading "1493: Uncovering the New World Columbus Created". Among the foods that have sustained the lives of Shanghainese during the lockdown, are potatoes, tomatoes, corn, peppers and sweet potatoes, all due to the great Columbian exchange more than five hundred years ago. These plants, which originated in Americas and spread to China, not only revolutionized the Chinese diet, but also greatly contributed to the growth of the Chinese population.
After 1492 the world's ecosystems collided and mixed as European vessels carried thousands of species to new homes across the oceans. The Columbian Exchange, as Crosby called it, is the reason there are tomatoes in Italy, oranges in the United States, chocolates in Switzerland, chili peppers in Thailand, and potatoes, maize and tomatoes in China.
For instance, tomatoes probably originated not in Mexico, but in the Andes Mountains. Half a dozen wild tomato species exist in Peru and Ecuador, all but one inedible, producing fruit the size of a thumbtack. And to botanists the real mystery is less how tomatoes ended up in Ukraine or Japan than how the progenitors of today's tomato journeyed from South America to Mexico, where native plant breeders radically transformed the fruits, making them bigger, redder, and, most important, more edible. Beginning in the sixteenth century, Europeans carried tomatoes around the world. After convincing themselves that the strange fruits were not poisonous, farmers planted them from Africa to Asia. In a small way, the plant had a cultural impact everywhere it moved.
The Columbian Exchange was a boon, and China raced to embrace it. "No large group of the human race in the Old World was quicker to adopt American food plants than the Chinese," Alfred W. Crosby wrote in The Columbian Exchange. Sweet potatoes, maize, peanuts, tobacco, chili peppers, pineapple, cashew, manioc (cassava)—all poured into Fujian (via the galleon trade), Guangdong (the province southwest of Fujian, via Portuguese ships in Macao), and Korea (via Japan, which took them from the Dutch). All became part of the furniture of Chinese life—who can imagine Sichuan food today without heaps of hot peppers?
"While men who stormed Tenochtitlan with Cortés still lived," Crosby said, "peanuts were swelling in the sandy loams near Shanghai; maize was turning fields green in south China; and the sweet potato was on its way to becoming the poor man's staple in Fujian." Today China is the world's biggest sweet potato grower, producing more than three-quarters of the global harvest; it is also the world’s second-biggest maize producer.
Key players were American crops, especially sweet potatoes and maize; their unexpected arrival was "one of the most revolutionary events" in imperial China’s history. The nation's agriculture, based on rice, had long been concentrated in river valleys, especially those of the Yangzi and Huang He (Yellow) rivers. Sweet potatoes and maize could be grown in the dry uplands. Farmers moved in numbers to these areas, which had previously been lightly settled.
Maize can thrive in amazingly bad land and grows quickly, maturing in less time than barley, wheat, and millet. Brought in from the Portuguese at Macao, it was known as "tribute wheat", "wrapped grain", and "jade rice". Sweet potatoes will grow where even maize cannot, tolerating strongly acid soils with little organic matter and few nutrients. I. batatas doesn’t even need much light.
How sweet potatoes entered China?
Epitomizing China's readiness to experiment was the Yuegang merchant Chen Zhenlong, who came across sweet potatoes (Ipomoea batatas) during a visit to Manila in the early 1590s. Probably native to Central America, I. batatas had been encountered by Colón on his first voyage; Spaniards had brought the species to the Philippines, where it was quickly adopted by Malays, who already grew the tuber crop taro.
Liking the taste, Chen decided to take sweet potatoes home with him. "He bribed the barbarians to get segments of their vines several feet in length," reported his great-great-great-grandson in True Account of the Story of Planting Sweet Potatoes in Qinghai, Henan, and Other Provinces (1768), a book-length essay devoted to bragging about the sweet potato feats of the author’s ancestors. Chen hid the vines by twisting them around ropes and tossing the ropes into a basket. Spanish customs agents noticed nothing. In this way Chen smuggled sweet potatoes into China. "Even though the vines were withered," his great-great-great-grandson wrote later, “they flourished after he stuck cuttings in infertile ground."
Chen Zhenlong and his friends seem initially to have thought of the fanshu—foreign tubers—as an amusing novelty; they gave them away as presents, a slice or two at a time, neatly wrapped in a box.
The 1580s and 1590s, an intense point in the Little Ice Age, were two decades of hard cold rains that flooded Fujianese valleys, washing away rice paddies and drowning the crop. Famine shadowed the rains. Poor families were reduced to eating bark, grass, insects, and even the seeds found in wild-goose excrement.
As hunger tightened its grip, Chen's son, Chen Jinglun, showed the fanshu to the provincial governor, to whom he was an adviser. The younger Chen was asked to conduct a trial planting near his home. Successful results persuaded the governor to distribute cuttings to farmers and instruct farmers how to grow and store them. "It was a great fall harvest; both near and far food was abundant and disaster was no longer a threat," exulted the great-great-great-grandson. Near Yuegang, as much as 80 percent of the locals were living on sweet potatoes.
In south China, many farmers' diets revolved around the sweet potato: sweet potatoes baked and boiled, sweet potatoes ground into flour for noodles, sweet potatoes mashed with pickles or deep-fried with honey or chopped into stew with turnips and soybean milk, even sweet potatoes fermented into a kind of wine.
How have potatoes changed Europe and China?
Potatoes belong to the nightshade family, which means they are cousins to tomatoes, eggplant, tobacco, sweet peppers, and deadly nightshade. When potato plants bloom, they send up five-lobed flowers that bob in fields like fat purple stars. According to tradition, Marie Antoinette liked the blossoms so much that she put them in her hair. Her husband, Louis XVI, supposedly put one in his buttonhole, inspiring a brief vogue in which the French aristocracy swanned around with potato plants on their clothes.
Today the potato is the fifth most important crop worldwide, surpassed in harvest volume only by sugarcane, wheat, maize, and rice. Originally it came from the Andes—not only Solanum tuberosum, the potato found in supermarkets, but many other types of potato that are eaten only in Ecuador, Peru, and Bolivia. There are also scores of wild potato species that can be found everywhere from Argentina to the southwestern United States.
Potatoes are about three-quarters water and one-quarter starch but have vitamins enough to prevent scurvy if consumed in quantity. For 167 days in 1925 two Polish researchers ate almost nothing but potatoes (mashed with butter, steamed with salt, cut with oil into potato salad). At the end they reported no weight gain, no health problems, and, improbably, "no craving for change" in their diet. Historically speaking, the scientists' regimen was not extreme; two British inquiries in 1839 intimated that the average Irish laborer’s per capita daily consumption of potatoes was twelve and a half pounds.
The potato can better sustain life than any other food when eaten as the sole item of diet. It has all essential nutrients except vitamins A and D, which can be supplied by milk; the diet of the Irish poor in Adam Smith's day consisted largely of potatoes and milk. And Ireland was full of poor folk; England had conquered it in the seventeenth century and seized much of the best land for its own citizens. Many of the Irish were forced to become sharecroppers, paid for their work by being allowed to farm little scraps of wet land for themselves. Because little but potatoes could thrive in this stingy soil, Ireland's sharecroppers were among Europe's most impoverished people. Yet they were also among its most well nourished, because they ate potatoes.
Not only did the Columbian Exchange carry the ultra-productive potato to Europe and North America, it also brought ultra-productive Andean potato-cultivation techniques, including the world’s first intensive fertilizer: Peruvian guano. Andean peoples had mined it for centuries from great excremental deposits seabirds left on coastal islands. Fertilizer ships crossed the Atlantic by the hundreds, brimming with guano—and, many researchers believe, a fungus-like organism that blighted potatoes, causing a famine in Ireland.
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.
In the west, China was a land of maize and another American import: potatoes, originally bred in the Andes Mountains. When the wandering French missionary Armand David lived in a hut in remote, scraggy Shaanxi, his meal plan would not have been out of place, except for a few garnishes, in the Inka empire. "The only plant cultivated near our cabin is the potato," he noted in 1872. "Maize flour, along with potatoes, is the mountain peoples' daily diet; it's usually eaten boiled and mixed with the tubers."
How have American crops contributed to China’s population growth?
Back in 1795, Sichuan was a big, roomy place: more land than California, a population as low as 9 million. Just 2,300 square miles of its surface, an area half the size of Los Angeles County, were considered arable. During the next twenty years, American crops moved into the ridges and highlands, increasing the pool of farmland to almost 3,700 square miles. As Sichuan's agricultural capacity increased, its population increased in tandem, to 25 million. Something similar occurred in Shaanxi Province, Sichuan's even emptier neighbor to the northeast. Migrants poured into the steep, arid hills along the border between them, knocking down the trees that clung to the slopes to make room for sweet potatoes, maize, and, later, potatoes. The amount of cropland soared, followed by the amount of food grown on that cropland, and then the population. In some places the number of inhabitants increased a hundredfold in little more than a century.
Source: Vaclav Smil, China's Environmental Crisis (1993)
From the arrival of American crops at the beginning of the new dynasty to the end of the eighteenth century, population soared. Most of the increase took place in the areas with American crops. The families that Qing policies encouraged to move west needed to eat, and what they ate, day in and day out, was maize, potatoes, and sweet potatoes. Part of the reason China is the world’s most populous nation is the Columbian Exchange.
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