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Columbian exchange
from 1492· Event· Human ancestors & us
Well establishedStrong fossil, genetic or geological evidence.
The swap of crops, animals and diseases between the Americas and the rest of the world that followed Columbus's 1492 voyage.
See it on the Life map →What happened
Plants, animals and microbes that had evolved apart for millions of years were suddenly traded across oceans. Maize, potatoes, tomatoes, cassava and chili peppers went east; chili reached Korea by the early 1600s and later turned kimchi red. Wheat, sugarcane, coffee, horses, cattle and pigs went west. So did smallpox, measles and influenza, which killed a large share of Indigenous Americans over the following century; estimates vary widely.
Why it matters
It rebuilt the world's diets and farms, fueled population growth in Asia, Africa and Europe, and set off one of history's worst demographic disasters in the Americas.
The evidence (fossils, genes, rocks)
Historian Alfred Crosby named it in 1972; ship records, colonial accounts, plant remains and crop DNA trace each species' movement and date.
Still debated
Pre-1492 population estimates for the Americas range from about 8 to over 100 million, so the death toll is debated; whether syphilis came from the Americas is also disputed.
Connections (3)
▸Horses returned to the Americas in Columbian exchangeWell established
The connection
Horses evolved mostly in North America and crossed to Asia over the Bering land bridge, but died out in the Americas by about 10,000 years ago. Spanish ships brought them back from 1493. Over the next two centuries horses spread across the Great Plains, where peoples such as the Comanche and Lakota built new horse-based ways of life.
When and how
Columbus's second voyage landed horses on Hispaniola in 1493; Cortés brought them to Mexico in 1519; horses reached the Great Plains and Rockies by the 1600s.
The evidence
Spanish records, Indigenous oral histories and, from 2023, radiocarbon-dated horse bones and DNA showing horses in Plains communities by the early 1600s.
Debates and open questions
How quickly horses spread north, often ahead of Europeans, and how to weigh Indigenous oral histories and Spanish records against the new bone dates.
▸Columbian exchange globalized Agriculture beginsWell established
The connection
Before 1492, the farming systems of the Americas and the Old World had developed separately for about 10,000 years. The exchange mixed them: potatoes fueled European population growth, maize and cassava spread through Africa, sweet potatoes and chili reached China and Korea, and wheat, cattle, sugar and coffee reshaped the Americas.
When and how
From 1492 on, carried by Spanish, Portuguese and later other ships across the Atlantic and, via Manila galleons from 1565, across the Pacific.
The evidence
Historical records date each crop's arrival, crop DNA and plant remains confirm origins; economists estimate potatoes drove about a quarter of Old World population growth, 1700–1900.
Debates and open questions
How much new crops, versus other factors, drove population booms in China, Africa and Europe, and how much American farmland reverted to forest after epidemics.
▸Columbian exchange is one proposed start of The AnthropoceneDebated
The connection
After 1492 crops, animals and diseases crossed between the hemispheres, mixing life globally. Epidemics killed a large share of the Americas' Indigenous peoples, and abandoned farmland regrew as forest, drawing down carbon dioxide. Simon Lewis and Mark Maslin argued this caused a 1610 dip in Antarctic ice cores, the 'Orbis spike', and proposed it as the Anthropocene's start.
When and how
The Americas, Europe, Africa and Asia, from 1492; the 1610 proposal was published by Lewis and Maslin in Nature in 2015.
How sure are we?
Antarctic ice cores show a carbon dioxide dip of about 7–10 parts per million around 1610, and sediments worldwide begin showing crops and species from other continents.
Debates and open questions
Death toll estimates vary widely, into the tens of millions; how much of the dip came from forest regrowth rather than natural cooling is disputed.