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Genetic modification caused by human activity has been occurring since around 12,000 BC, when humans first began to domesticate organisms. Genetic engineering as the direct transfer of DNA from one organism to another was first accomplished by Herbert Boyer and Stanley Cohen in 1973. Advances have allowed scientists to manipulate and add genes to a variety of different organism and induce a range of different effects. Since 1976 the technology has been commercialised, with companies producing and selling genetically modified food and medicine. ==Agriculture== (詳細はdomestication of plants and animals through artificial selection. The dog is believed to be the first animal domesticated, most likely arising from the grey wolf, with fossil evidence dating to about 12,000 BC. The other carnivores domesticated in prehistoric times were the cat and polecat.〔 Sheep and goats were domesticated around 8,000 BC in the Fertile Crescent, while pigs appeared in China about 7,000 BC, yaks in Tibet about 5,000 BC and horses in Eastern Europe around 4,000 BC.〔 The first domesticated bird was the rock pigeon, appearing in Greece, Egypt and Mesopotamia around 3,000 BC 〔 and the first domesticated fish was probably carp, raised as food in China around 1,000 BC.〔 The first evidence of plant domestication comes from emmer and einkorn wheat found in pre-Pottery Neolithic A villages in Southwest Asia dated about 10,500 to 10,100 BC. The Fertile Crescent of Western Asia, Egypt, and India were sites of the earliest planned sowing and harvesting of plants that had previously been gathered in the wild. Independent development of agriculture occurred in northern and southern China, Africa's Sahel, New Guinea and several regions of the Americas.〔(the history of maize cultivation in southern Mexico dates back 9000 years. ) ''New York Times'', accessdate=2010-5-4〕 The eight Neolithic founder crops (emmer wheat, einkorn wheat, barley, peas, lentils, bitter vetch, chick peas and flax) had all appeared by about 7000 BC. Horticulture first appears in the Levant during the Chalcolithic period about 6 800 to 6,300 BC.〔 Due to the soft tissues, archeological evidence for early vegetables is scarce. The earliest vegetable remains have been found in Egyptian caves that date back to the 2nd millennium BC.〔 Selective breeding of domesticated plants was once the main way early farmers shaped organisms to suit their needs. Charles Darwin described three types of selection: methodical selection, wherein humans deliberately select for particular characteristics; unconscious selection, wherein a characteristic is selected simply because it is desirable; and natural selection, wherein a trait that helps an organism survive better is passed on.〔 Noel Kingsbury. (Hybrid: The History and Science of Plant Breeding ) University of Chicago Press, Oct 15, 2009〕 Early breeding relied on unconscious and natural selection. The introduction of methodical selection is unknown.〔 Common characteristics that were bred into domesticated plants include grains that did not shatter to allow easier harvesting, uniform ripening, shorter lifespans that translate to faster growing, loss of toxic compounds, and productivity.〔 Some plants, like the Banana, were able to be propagated by vegetative cloning. Offspring often did not contain seeds, and therefore sterile. However, these offspring were usually juicier and larger. Propagation through cloning allows these mutant varieties to be cultivated despite their lack of seeds.〔 Hybridization was another way that rapid changes in plant's makeup were introduced. It often increased vigor in plants, and combined desirable traits together. Hybridization most likely first occurred when humans first grew similar, yet slightly different plants in close proximity.〔 Triticum aestivum, wheat used in baking bread, is an allopolyploid. Its creation is the result of two separate hybridization events. X-rays were first used to deliberately mutate plants in 1927. Between 1927 and 2007, more than 2,540 genetically mutated plant varieties had been produced using x-rays. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「History of genetic engineering」の詳細全文を読む スポンサード リンク
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