A week of HST 101.

The meal no one could eat before 1492

HST 101 · The Columbian Exchange · about 690 words

In a single day you might eat a potato, a tomato, some chocolate, and chicken with rice. Before 1492, no one on Earth could have eaten that meal, because its ingredients came from opposite sides of the Atlantic. Potatoes, tomatoes, and cacao were American. Chickens and rice came from Asia by way of Europe and Africa. In 1972, the historian Alfred Crosby gave the great mixing that followed Columbus's voyages a name: the Columbian Exchange.

For more than ten thousand years, since the end of the last Ice Age, the Americas and Afro-Eurasia had developed largely apart. After 1492, regular ocean crossings connected the two halves of the world, and living things began moving in both directions, some on purpose and some by accident.

From the Americas came maize (corn), potatoes, sweet potatoes, cassava, beans, squash, peanuts, tomatoes, chili peppers, and cacao. Several of these crops grew well in soils or climates where older staples struggled, and some produced more calories per acre. The potato became a staple across much of northern Europe. Maize and sweet potatoes spread in China, and maize and cassava became major foods in parts of Africa.

Many historians think these crops helped world population grow in the centuries after 1700. How much they helped is still debated, but the effect on diets is clear.

Traffic in the other direction included wheat, sugarcane, bananas, coffee, and citrus fruits, along with animals the Americas had lacked. Before 1492, the only large domesticated animals in the Americas were llamas and alpacas in the Andes. Now came horses, cattle, pigs, sheep, goats, and chickens. Horses, which had died out in the Americas thousands of years earlier, transformed life on the Great Plains, where peoples such as the Comanche and Lakota became expert riders and bison hunters.

The most devastating part of the exchange was invisible. People in Afro-Eurasia had lived for centuries with diseases such as smallpox, measles, and influenza. In those societies, many adults had survived these illnesses as children and were immune. People in the Americas had never been exposed. When the diseases arrived, they spread through communities where almost no one was immune.

The results were catastrophic. Scholars estimate that the population of the Americas in 1492 was somewhere around 40 to 60 million people, though some estimates run much lower or higher. By around 1600, most estimates suggest it had fallen by something like 80 to 90 percent. These numbers are built from incomplete records and are still argued over, but nearly all historians agree that this was one of the largest population collapses in human history.

Disease did not act alone. War, enslavement, forced labor in mines and on plantations, and disrupted food supplies all made people more vulnerable and slowed recovery. Separating the effects of germs from the effects of violence is one of the hardest problems in the history of this period.

People moved too. Millions of Europeans crossed the Atlantic, but before about 1820, far more Africans made the crossing, and they did not choose to. According to the Trans-Atlantic Slave Trade Database, roughly 12.5 million Africans were forced onto ships bound for the Americas over about three and a half centuries, and around 10.7 million survived the voyage. Most were put to work growing sugar, tobacco, rice, cotton, and coffee.

These flows reshaped economies on both sides of the ocean. Sugar, once a rare luxury in Europe, became an everyday food, grown on plantations in Brazil and the Caribbean that depended on enslaved labor. Silver mined in the Americas, much of it at Potosí in present-day Bolivia, flowed to Europe and across the Pacific to China, helping tie the world's regions into a global trading network.

The Columbian Exchange is hard to sum up in a single judgment, because it was many things at once. It enriched diets and helped feed growing populations. It also brought death on an enormous scale and helped build an economy based on slavery. Historians study it because it shows that the past is shaped not only by rulers and battles but by seeds, animals, and germs, often carried by people who had no idea what they were starting.

Sources: A. W. Crosby, The Columbian Exchange: Biological and Cultural Consequences of 1492 (1972); N. Nunn and N. Qian, "The Columbian Exchange: A History of Disease, Food, and Ideas," Journal of Economic Perspectives (2010); Trans-Atlantic Slave Trade Database, SlaveVoyages.org.