Origins of Agriculture

The origin of agriculture was around ten thousand years ago or approximately four hundred human generations back in time and prehistory, before written records were kept. What is known is based on evidence gathered from archaeological sites. Agriculture started independently in at least three places in the world, each with a distinctive cluster of plants drawn from the local flora: Mesoamerica (Mexico/Guatemala: corn, beans, squash, papaya, tomatoes, chili, peppers), the Fertile Crescent (Middle East from the Nile Valley to the Tigris and Euphrates Rivers: wheat, barley, grapes, apples, figs, melons, lentils, dates), and north China (mid-reaches of the three-thousand-mile-long Yellow River: rice, soybeans, peaches, Chinese cabbages such as bok choy). From these regions and possibly others, notably Africa (sorghum, cowpeas, yams, oil palm), South America (potatoes, sweet potatoes, cassava, peanuts, pineapples), and a broad band of tropical southeast Asia (oranges, mangoes, bananas, coconuts, sugarcane), the invention of agricultures spread to encompass the entire world by two thousand years ago.

The history of agriculture is not that of a single technology to produce food, but of an array of methodologies. Planting seed broadcast across plowed fields typifies most cereals (50 percent of human calories). Vegetables, legumes, and corn are planted from seed in rows separated by furrows. Seed agriculture usually consists of annuals that are typically planted as genetically uniform monocultures. Agriculture of the humid tropics has been more vegeculture than seed-based. These vegetatively propagated crops are usually perennials, productive over the entire year and found in polycultures that tend to mimic the forest ecosystem.

The earliest agriculture of southeast Asia was typically based on roots and tubers such as yams and taro, tree crops such as coconut and banana, and perennials such as sugarcane. In the Americas, vegeculture developed with cassava, sweet potatoes, arrowroot, and peanuts, and moved up the eastern slopes of the Andes, ultimately domesticating the potato. These crops spread quickly throughout the world after European contact. Potatoes displaced wheat and barley in cold soils of northern Europe and bananas became the fruit of choice in the New World tropics.

Seed agriculture dominates where either a pronounced dry season or a frost results in a single crop per year. In south China rice is the summer crop, sweet potato the winter crop. In India rice is the monsoon crop, wheat the winter crop. Sometimes intercropping (different crops in alternate rows) and relay planting (starting the next crop before the previous one is harvested) are part of the multiple-crops-per-year cycle. Sequential cropping is where one crop follows another without seasonal fallowing, sometimes in double-cropping but more often in triple-cropping.

Fallowing is an important technology perfected in the Middle Ages as part of the crop rotation pattern. The first year a legume is planted and the soil is enriched by the nitrogen-fixing crop; the next year a cereal is planted. The third year the land is rested to regain soil moisture and restore soil health. This pattern approximates a natural ecosystem and is more sustainable over the long term than continuous cropping. The fallow crop rotation system maximizes resources but is not elastic enough to accommodate an increasing human population that has come to rely on continuous cropping or heavy use of inputs (such as fertilizer, pesticides, and irrigation) in single crop per year monocultures.

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