Genetic modification caused by human activity has been occurring since humans first domesticated organisms in 12 000 BC. 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 to induce a range of different effects. Since 1976 the technology has been commercialised, with companies producing and selling genetically modified food and medicine.
Main article: History of agriculture
The first human manipulation of genes occurred during the 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 eight Neolithic founder crops (emmer wheat, einkorn wheat, barley,