Agrarian society
Agrarian society were preceded by hunter and gatherer and horticultural societies and transition into industrial society. The transition to agriculture, called the Neolithic Revolution, has taken place independently multiple times. Horticulture and agriculture as types of subsistence developed among humans somewhere between 10,000 and 8,000 years ago in the Fertile Crescent region of the Middle East. The reasons for the development of agriculture are debated but may have included climate change, and the accumulation of food surplus for competitive gift-giving. Most certainly there was a gradual transition from hunter-gatherer to agricultural economies after a lengthy period when some crops were deliberately planted and other foods were gathered from the wild. In addition to the emergence of farming in the Fertile Crescent, agriculture appeared in: by at least 6,800 B.C.E. in East Asia (rice) and, later, in Central and South America (maize and squash). Small-scale agriculture also likely arose independently in early Neolithic contexts in India (rice) and Southeast Asia (taro). However, full dependency on domestic crops and animals, when wild resources contributed a nutritionally insignificant component to the diet, did not occur until the Bronze Age.
Agriculture
In the Middle Ages, both in the Islamic world and in Europe, agriculture was transformed with improved techniques and the diffusion of crop plants, including the introduction of sugar, rice, cotton and fruit trees such as the orange to Europe by way of Al-Andalus. After 1492, the Columbian exchange brought New World crops such as maize, potatoes, tomatoes, sweet potatoes and manioc to Europe, and Old World crops such as wheat, barley, rice and turnips, and livestock including horses, cattle, sheep and goats to the Americas.
Irrigation, crop rotation, and fertilizers were greatly developed in the past 200 years, starting with the British Agricultural Revolution, allowing global population to rise significantly. Since 1900, agriculture in the developed nations, and to a lesser extent in the developing world, has seen large rises in productivity as human labor has been replaced by mechanization, and assisted by synthetic fertilizers, pesticides, and selective breeding. The Haber-Bosch method allowed the synthesis of ammonium nitrate fertilizer on an industrial scale, greatly increasing crop yields and sustaining a further increase in global population. Modern agriculture has raised political issues including water pollution, biofuels, genetically modified organisms, tariffs and farm subsidies, leading to alternative approaches such as the organic movement.