AP® Human Geography review sheet from Aim for Five (aimforfive.com/geo/units/5/5-3)
Unit 5 · Topic 5.3
5.3 Agricultural Origins and Diffusions
Farming began independently in several hearths, starting about 11,000 years ago in the Fertile Crescent, and spread outward by diffusion. After 1492 the Columbian Exchange moved crops, animals and diseases between the Americas and the rest of the world, reshaping diets and populations on every continent.
Key terms
- First Agricultural Revolution
- agricultural hearth
- domestication
- Fertile Crescent
- Columbian Exchange
The First Agricultural Revolution
For most of human history, people got food by hunting, fishing and gathering. The First Agricultural Revolution (also called the Neolithic Revolution) was the shift to growing crops and raising animals. It depended on domestication: over many generations, people selected and bred wild plants and animals until they changed into forms that rely on humans, like wheat whose seeds stay on the stalk for harvest.
Farming produced a food surplus, more than the farmers themselves needed. A surplus let people settle in one place, support larger populations, and free some people to become crafts workers, traders, priests and rulers. Those changes led to the first cities and states (6.1).
Hearths of domestication
An agricultural hearth is a place where people domesticated plants or animals. Farming wasn't invented once and copied everywhere; it started independently in several regions. Dates are approximate, and archaeologists revise them as new evidence turns up.
| Hearth | Roughly when | Examples of what was domesticated |
|---|---|---|
| Fertile Crescent (Southwest Asia) | About 11,000 years ago | Wheat, barley, lentils, peas; sheep, goats, cattle, pigs |
| Yellow and Yangtze river valleys (East Asia) | About 9,000 years ago | Millet, rice; pigs |
| Indus River Valley (South Asia) | About 9,000 years ago | Wheat, barley, later cotton; zebu cattle |
| Southeast Asia and New Guinea | About 7,000 to 10,000 years ago | Taro, yams, bananas, sugarcane |
| Mesoamerica (southern Mexico and Central America) | About 9,000 years ago | Maize (from a wild grass called teosinte), beans, squash |
| Andes (South America) | About 6,000 to 10,000 years ago | Potatoes, quinoa; llamas, alpacas |
| Sub-Saharan Africa (the Sahel, West Africa and the Ethiopian highlands) | About 3,000 to 7,000 years ago | Sorghum, pearl millet, African rice, yams, teff |
How farming spread
From each hearth, farming diffused. Some of this was relocation diffusion: farming peoples moved into new lands and brought their seeds and animals. Some was expansion diffusion: neighbors saw farming work and adopted it. Crops from the Fertile Crescent spread into Europe, North Africa and South Asia over thousands of years. Crops tended to spread more easily into areas with similar climates and day lengths.
The Columbian Exchange
After Columbus reached the Americas in 1492, plants, animals, people and diseases moved across the Atlantic in both directions. This Columbian Exchange is one of the biggest examples of diffusion in history.
- From the Americas to the rest of the world: maize, potatoes, tomatoes, cassava, cacao, peppers, peanuts, squash, tobacco.
- To the Americas: wheat, rice, sugarcane, coffee, bananas; horses, cattle, pigs, sheep, chickens.
- Diseases: smallpox, measles and influenza killed a large share of Indigenous peoples in the Americas, who had no prior exposure.
- Population effects: potatoes and maize became staple foods in Europe, Africa and China and supported population growth. Ireland came to depend so heavily on the potato that a potato blight caused the Great Famine of 1845–1849.
- Labor and land: sugar, coffee and cotton plantations in the Americas were built on the forced labor of enslaved Africans, linking the exchange to the Atlantic slave trade.
- Cultural change: horses transformed life for Plains nations such as the Comanche and Lakota, who became skilled horse-mounted hunters.
Worked examples
Try each one yourself first, then open the solution.
- Example 1
A causation chain
Explain one effect of the Columbian Exchange on population in Europe or Africa.
Show the solutionHide the solution
- Step 1: Name a specific crop that moved: the potato or maize, from the Americas.
- Step 2: Explain the mechanism: these crops produce a lot of calories per acre and grow in places where other staples did poorly.
- Step 3: State the effect at a named scale: more food supported population growth.
Answer: Model answer: The Columbian Exchange brought the potato from the Andes to Europe. Because potatoes yield many calories per acre and grow well in cool, wet climates, they became a staple in places like Ireland and northern Europe and helped support rapid population growth in the 1700s and 1800s.
Common mistakes
- Saying farming began in one place and spread everywhere from there. Multiple hearths domesticated different crops independently.
- Getting the direction of a crop wrong. Potatoes, maize, tomatoes and cacao came from the Americas; wheat, sugarcane, coffee and horses went to the Americas.
- Leaving out the human costs. A complete answer about the Columbian Exchange includes disease deaths among Indigenous peoples and the expansion of slavery.
On the exam
- Be ready to name a hearth and one crop or animal domesticated there, and to explain how domestication led to settled life and population growth.
- Columbian Exchange questions often ask for a positive or negative effect. Give a specific crop or disease and a specific region.
Connected topics
Videos
Check yourself
4 questions on 5.3 Agricultural Origins and Diffusions. Pick an answer to see if you got it, and why.
Which pair correctly matches an agricultural hearth with crops first domesticated there?
Within two centuries of 1492, the potato, first domesticated in the Andes, had become a staple food across much of northern Europe, where it produced more calories per acre than grains in cool, damp conditions. In parts of West and Central Africa, maize and cassava from the Americas became major food crops.
Movement in the other direction transformed the Americas. Horses reshaped hunting and travel on the Great Plains, and cattle and sheep spread across the grasslands of Mexico and Argentina. Diseases such as smallpox, which Indigenous Americans had never been exposed to, killed a large share of the population.
Secondary-style passage written for this practice set
Which effect of the exchange is best supported by the passage?
Which crop moved across the Atlantic in the same direction as the potato?
Heavy dependence on a crop spread by the exchange contributed most directly to which later event?
0 of 4 answered