What happened
Beginning with Columbus’s voyages, crops, livestock, people, and pathogens crossed the Atlantic in both directions. The exchange linked hemispheres that had been biologically separate for thousands of years.
Background
The Americas sent maize, potatoes, tomatoes, cacao, and tobacco outward, while the Old World brought wheat, sugar, horses, cattle, and pigs. It also drove the forced movement of millions of enslaved Africans to the Americas.
Consequences
American crops fueled population growth across Europe, Africa, and Asia, and horses and cattle transformed American life. Its darkest side was the epidemics — smallpox above all — that killed a large share of Indigenous Americans.