What Was the Columbian Exchange? The Swap That Remade Every Cuisine

Europe and Africa sent to the Americas a package of domesticated animals and cereals that transformed the landscape. Cattle, pigs, sheep, goats, chickens and, most consequentially, horses arrived within a few decades, and several escaped and multiplied enormously in grasslands that had held no large grazers since the ice age; the horse cultures of the Great Plains, which look ancient from outside, are a post-contact development built on animals that arrived with the Spanish. Wheat, barley, rice, sugar cane, coffee, bananas and citrus followed, along with the plantation system that grew sugar and coffee using enslaved labour. Weeds and rats came uninvited. The sugar and coffee economies in particular reoriented the continent, since both are labour-intensive tropical crops with enormous European demand, which is the direct economic engine of the transatlantic slave trade.

The American crops that crossed the other way were mostly plants, and their effect on world nutrition was larger than any of the animals' on the Americas:

• •Potatoes, which yield more calories per hectare than any grain and grow in cool, poor soil, and which became the staple of northern Europe
• •Maize, which spread through Africa, southern Europe and China and now feeds more people and livestock than any other crop
• •Cassava, drought-resistant and storable in the ground, now a staple for hundreds of millions in Africa
• •Tomatoes, which took two centuries to be widely eaten in Europe because they belong to the nightshade family and were suspected of being poisonous
• •Chilli peppers, which travelled with Portuguese traders and were absorbed into Indian, Chinese, Korean and Southeast Asian cooking so completely that they read as indigenous
• •Cacao, vanilla, peanuts, pineapples, avocados, squashes, beans, sweet potatoes, sunflowers, tobacco and rubber
• •Notably missing in the other direction was any significant American domesticated animal, since the llama, alpaca, guinea pig and turkey were the entire list

The most consequential transfer was microbial and it went overwhelmingly one way. Eurasia had domesticated many herd animals over thousands of years, and had accumulated the crowd diseases that jump from livestock to people and require dense populations to persist: smallpox, measles, influenza, typhus, mumps, diphtheria and whooping cough. The Americas had almost no domesticated herd animals, no equivalent disease pool and no acquired immunity to any of it. The result was mortality without parallel, with estimates of the indigenous population decline commonly in the range of eighty to ninety-five percent over the century and a half after contact, driven by successive epidemics that often ran ahead of the Europeans themselves, so that societies collapsed before any European saw them. A 2019 study calculated that the abandonment of farmland on this scale allowed enough forest regrowth to measurably lower atmospheric carbon dioxide, contributing to the cooling of the Little Ice Age. The only disease that may have travelled east is syphilis, whose origin remains genuinely disputed.

The new crops caused population growth on other continents as dramatic as the collapse in the Americas. The potato is estimated to account for a substantial share of European population growth between 1700 and 1900, and the maize and sweet potato allowed Chinese farmers to cultivate hilly land unsuited to rice, which contributed to a population roughly tripling during the Qing period. Cassava and maize did comparable work in Africa, though the gain there sits alongside the catastrophe of the slave trade, which removed an estimated twelve million people. The dependence created its own risks: Ireland's population had grown to rely on a small number of potato varieties, and when a water mould arrived from the Americas in the 1840s it destroyed successive harvests, killing about a million people and driving a million more to emigrate, a famine whose severity owed as much to British policy and to land tenure as to the blight itself.

The culinary result is that most national cuisines regarded as traditional are post-1492 constructions. Italian food without tomatoes, Indian and Thai food without chillies, Hungarian food without paprika, Korean food without the chilli in gochujang, Belgian and Dutch food without the potato, and West African food without cassava and maize are all unimaginable, and all are younger than the sixteenth century. The pattern runs the other way too, since the beef of Argentina, the coffee of Brazil and Colombia, the wheat of the American Midwest, the wine of Chile and the citrus of Florida and California are all transplants. The exchange also created the pattern of world agriculture in which crops are grown far from where they were domesticated, which raises the risk that a disease reaching a crop's home region finds its wild relatives, and which is why seed banks holding the genetic diversity of each crop's origin area matter so much.

The transfer of organisms across the Atlantic after 1492, named by Alfred Crosby in 1972, moved horses, cattle, pigs, wheat, sugar and coffee west and potatoes, maize, cassava, tomatoes, chillies and cacao east. The American crops drove population growth across Europe, Asia and Africa, while Eurasian crowd diseases, which had arisen from millennia of living with herd animals, killed an estimated eighty to ninety-five percent of the indigenous population of the Americas. Most cuisines now considered traditional depend on ingredients that arrived after 1492.