Tomatoes in Italy, chili peppers in India and potatoes in Ireland all arrived after 1492. This episode looks at the Columbian Exchange, a term historian Alfred W. Crosby coined in 1972 for the transfer of plants, animals, diseases and people between the Old World and the New World after Columbus’s voyages. We explain how the potato drove an estimated 12 to 25 percent of population growth across Europe, Asia and Africa between 1700 and 1900, how cassava became Africa’s key crop, why transplanted crops enjoyed a yield honeymoon away from their native pests, and how enslaved Africans supplied the expertise behind rice cultivation in the Americas.

We also cover the lopsided exchange of animals, which the sources connect to the east-west axis of Eurasia and the north-south axis of the Americas, and how the Plains Indians and the Mapuche took up the horse. Then we turn to the catastrophe: virgin soil epidemics that killed an estimated 80 to 95 percent of Indigenous people in the Americas, the debate over whether syphilis came from the New World, and how sugar plantations, malaria and the sickle cell trait shaped the transatlantic slave trade.

• How New World crops like the potato and cassava fueled population growth and urbanization
• Ecological release and the yield honeymoon of transplanted crops
• Why the Americas had so few domesticated animals and how Indigenous peoples adopted the horse
• Virgin soil epidemics and the evidence on the origins of syphilis
• How disease and sugar production drove the transatlantic slave trade