What was the Columbian Exchange?

The Columbian Exchange, also called the Columbian interchange, was the widespread transfer of plants, animals and diseases between the Americas and Afro-Eurasia from the late 15th century on. It is named after Christopher Columbus and is tied to the European colonization and global trade that followed his 1492 voyage. Some transfers were deliberate and others were accidental. [1]

The historian Alfred Crosby, whose 1972 book gave the process its name in scholarship, described the mixing of plants, animals and bacteria as one of the most important ecological events in human history. [2] [3]

Crosby explains that continental drift separated the Old and New Worlds millions of years ago, and the long separation produced divergent evolution. Before 1492, wheat, barley, rice and turnips had not crossed the Atlantic westward, and maize, white potatoes, sweet potatoes and manioc had not travelled east. The Americas had no horses, cattle, sheep or goats. Apart from the llama, alpaca, dog, guinea pig and a few fowl, they lacked the domesticated animals of the Old World. [3]

Plants were the most exchanged items. Corn, potatoes, cassava, sweet potatoes, tomatoes, peanuts, cacao, vanilla and tobacco went from the Americas to the Eastern Hemisphere. Bananas, sugarcane, grapes, wheat, rice, onions, oranges and coffee went the other way. Crosby notes that American crops such as maize in China and the potato in Ireland stimulated population growth in the Old World, while wheat and cattle had similar effects in the Americas. [4] [3]

On his second voyage in 1493, Columbus brought animals including horses, dogs, pigs, cattle, chickens, sheep and goats to the Caribbean. Pizarro is said in one source to have seen the potato in the Andes in the 1530s and brought it to Europe. Introduced animals often thrived, both wild and domesticated, in part because they were less vulnerable to disease than people. [2] [5]

Old World diseases such as smallpox, measles, chickenpox, mumps, influenza, malaria and yellow fever reached peoples who had no prior exposure and no immunity. Wikipedia states that these diseases caused an 80 to 95 percent reduction in the Indigenous population of the Americas over the following centuries and near extinction in the Caribbean. Crosby attributes this to environmental contrast rather than any inherent difference between peoples: Amerindians had not adapted to European germs, so their numbers initially plunged. [1] [5] [3]

People moved too. European colonists and enslaved Africans replaced Indigenous populations to varying degrees, and in the first three centuries after Columbus far more Africans than Europeans were taken to the New World. Europeans forcibly transported enslaved Africans to provide labor. [1] [2]

Crosby argues that crops from the Americas, including maize, potatoes, sweet potatoes, squashes, chiles and manioc, became essentials in the diets of hundreds of millions of people in Europe, Africa and Asia, and that the exchange was an indispensable factor in the global population growth of the past three centuries. The DPLA notes that contact between Europe and the Americas did occur before 1492, but Columbus's contact set off a transfer of a much larger scale and lasting significance. [3] [2]