The Three Agricultural Revolutions and What Each One Changed

First Agricultural Revolution (Neolithic Revolution)

Roughly 10,000 years ago humans began the domestication of plants and animals. This did not happen once and spread; it happened independently in several agricultural hearths — the Fertile Crescent (wheat, barley, sheep, goats), East and South Asia (rice, taro, pigs), Mesoamerica (maize, beans, squash), the Andes (potato, quinoa, llama), and West Africa (sorghum, yams).

The decisive consequence was not more food but sedentism: a field must be guarded and harvested at a fixed place, so people stopped moving. Fixed settlement produced property in land, storable surplus, and therefore social stratification — the first societies with rulers, priests and specialists who did not grow food.

Second Agricultural Revolution (17th–19th centuries)

Tied to the Industrial Revolution in Europe and North America. Its components: improved crop rotation that removed the fallow year, selective breeding, the seed drill, the enclosure movement that consolidated open fields into private holdings, mechanization, and then railroads and refrigerated shipping.

The consequence AP asks about is demographic: fewer farmers could feed more people. Labour released from the land became the urban industrial workforce, and improved, more reliable nutrition pushed death rates down — this is what moves a country into Stage 2 of the demographic transition.

Green Revolution (1950s–1970s)

The diffusion of high-yield varieties (HYVs) of wheat, rice and maize — associated with Norman Borlaug — bundled with chemical fertilizer, pesticides, irrigation and mechanization. Mexico, India and Southeast Asia moved from grain importers to self-sufficiency within a generation.

The costs are equally examinable: HYVs only outperform local varieties when the purchased inputs are supplied, so the gains concentrated among farmers with capital, credit and irrigation. Environmental costs include aquifer depletion, soil salinization, fertilizer runoff and loss of crop genetic diversity. Sub-Saharan Africa was largely bypassed: its dominant crops were not the target crops, and irrigation, roads and rural credit were largely absent.