Disease and Demographic Catastrophe in the Americas

The most devastating part of the Columbian Exchange was disease. Indigenous peoples of the Americas had no prior exposure to smallpox, measles and influenza, which Europeans and Africans had lived with for centuries. When these diseases arrived, often ahead of the colonizers themselves, they caused repeated epidemics that killed a very large share of the population. Smallpox struck Hispaniola by 1518 and ravaged Tenochtitlan in 1520, weakening its defenders before the Spanish siege.

Scholars debate both the size of the pre-contact population, with estimates ranging from under ten million to over one hundred million, and the death toll, but most agree that many regions lost the majority of their people within a century. Historians also stress that disease worked together with war, forced labour and displacement, so the collapse was not simply natural. This sober history shapes how we understand conquest and global contact.