The Columbian Exchange

Imagine the menu without them

Picture Italian food without tomatoes, Irish food without potatoes, Thai or Sichuan food without chili peppers, Swiss chocolate without cacao, or poutine without fries. Before 1492, all of these were impossible: those plants grew only in the Americas. Now picture the Prairies without wheat or cattle, or the Plains Nations without horses: those came from Afro-Eurasia.

The historian Alfred W. Crosby called this movement of plants, animals, microbes and people between the hemispheres the Columbian Exchange (1972). It may be the most far-reaching consequence of 1492.

What moved, and which way?

From the Americas to Afro-Eurasia: maize (corn), potatoes, sweet potatoes, cassava (manioc), tomatoes, chili peppers, beans, squash, peanuts, cacao, vanilla, tobacco and turkeys.

From Afro-Eurasia to the Americas: wheat, rice, barley, sugar cane, bananas and citrus; horses, cattle, pigs, sheep, goats and chickens; honeybees; and diseases such as smallpox, measles, influenza and typhus. Malaria and yellow fever arrived from Africa, carried along the routes of the slave trade.

These American crops were not wild finds. They were the result of thousands of years of plant breeding by Indigenous farmers: maize was developed from a wild grass in Mexico, and Andean farmers bred thousands of potato varieties. The Columbian Exchange spread Indigenous agricultural science around the world.

Consequences in the Americas

• Disease: epidemics were the main cause of the catastrophic Indigenous population decline described in Conquest and Colonization in the Americas. Indigenous peoples had no prior exposure to these Afro-Eurasian diseases.
• Animals and land: pigs and cattle multiplied quickly and trampled Indigenous fields. In parts of Mexico, large flocks of sheep contributed to erosion and land degradation. Ranching took land from Indigenous farming.
• Horses: in the long term, many Nations of the Plains made horses central to their economies and cultures; this mostly came after 1650 (see the sibling unit The World, 1650–1789).
• Sugar: sugar cane, grown on plantations, created an enormous demand for labour. As Indigenous populations collapsed, planters turned to enslaved Africans (next lesson). Sugar, disease and slavery are linked.

Consequences in Afro-Eurasia

• Food and population: American crops grew well where Old World crops did poorly. In China, maize and sweet potatoes, arriving in the late 1500s, could be grown on hillsides and poor soil, and helped support later population growth. In Africa, maize and cassava became staple foods in many regions. The potato eventually became a staple in northern Europe, mostly after 1650.
• Cuisine and culture: chili peppers spread from the Americas into the cooking of India, Southeast Asia, China and Africa within about a century.
• Tobacco spread worldwide as a trade good, despite rulers who tried to ban it.
• Silver, though not living, was part of the same exchange: American silver flowed to Europe and China and changed prices and taxes (see Ming China and East Asia).

A two-way but unequal exchange

The exchange benefited Afro-Eurasia's population and food supply, while bringing disease, dispossession and enslavement to the Americas and Africa. Historians also note that the very name "Columbian" centres Columbus. Some prefer terms like the "Atlantic exchange" or "biological exchange". Crosby also coined "ecological imperialism" for the way European crops, animals and diseases helped Europeans take over lands in temperate regions.