Vegetable farming is the growing of vegetables for human consumption. The practice probably started in several parts of the world over ten thousand years ago, with families growing vegetables for their own consumption or to trade locally. At first manual labour was used but in time livestock were domesticated and the ground could be turned by the plough. More recently, mechanisation has revolutionised vegetable farming with nearly all processes being able to be performed by machine. Specialist producers grow the particular crops that do well in their locality. New methods—such as aquaponics, raised beds and cultivation under glass—are used. Marketing can be done locally in farmer's markets, traditional markets or pick-your-own operations, or farmers can contract their whole crops to wholesalers, canners or retailers. History Originally, vegetables were collected from the wild by hunter-gatherers and entered cultivation in several parts of the world, probably during the period 10,000 BC to 7,000 BC, when a new agricultural way of life developed. At first, plants which grew locally would have been cultivated, but as time went on, trade brought exotic crops from elsewhere to add to domestic types. Nowadays, most vegetables are grown all over the world as climate permits. Traditionally it was done in the soil in small rows or blocks, often primarily for consumption on the farm, with the excess sold in nearby towns. Later, farms on the edge of large communities could specialize in vegetable production, with the short distance allowing the farmer to get his produce to market while still fresh. The three sisters method used by Native Americans (specifically the Haudenosaunee/Iroquois) grew squash, beans and corn together so that the plants enhanced each other's growth. Planting in long rows allows machinery to cultivate the fields, increasing efficiency and output; however, the diversity of vegetable crops requires a number of techniques to be used to optimize the growth of each type of plant. Some farms, therefore, specialize in one vegetable; others grow a large variety. Due to the needs to market vegetables while fresh, vegetable gardening has high labor demands. Some farms avoid this by running u-pick operations where the customers pick their own produce. The development of ripening technologies and refrigeration has reduced the problems with getting produce to market in good condition. Different growing methods Over the past 100 years a new technique has emerged—raised bed gardening, which has increased yields from small plots of soil