Agriculture is the cultivation of land and breeding of animals and plants to provide food, fiber, medicinal plants and other products to sustain and enhance life.Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people to live in cities. The study of agriculture is known as agricultural science. The history of agriculture dates back thousands of years; people gathered wild grains at least 105,000 years ago, and began to plant them around 11,500 years ago, before they became domesticated. Pigs, sheep, and cattle were domesticated over 10,000 years ago. Crops originate from at least 11 regions of the world. Industrial agriculture based on large-scale monoculture has in the past century become the dominant agricultural method.Modern agronomy, plant breeding, agrochemicals such as pesticides and fertilizers, and technological developments have sharply increased yields from cultivation, but at the same time have caused widespread ecological damage. Selective breeding and modern practices in animal husbandry have similarly increased the output of meat, but have raised concerns about animal welfare and environmental damage through contributions to global warming, depletion of aquifers, deforestation, antibiotic resistance, and growth hormones in industrially produced meat. Genetically modified organisms are widely used, although they are banned in several countries.The major agricultural products can be broadly grouped into foods, fibers, fuels, and raw materials. Classes of foods include cereals (grains), vegetables, fruits, oils, and meat. Over one third of the world’s workers are employed in agriculture, second only to the service sector, although the number of agricultural workers in developed countries has decreased significantly over the past several centuries.