The first known genetic engineering technique, that is still used today, was the elective breeding of plants and animals. This was usually used to increase food production. In selective breeding, only the plants or animals with desirable characteristics are chosen for further breeding. Corn has been selectively bred for increased kernel size and number and for nutritional content for about 7,000 years. More recently, selective breeding of wheat and rice has been promoted to produce higher yields has helped supply the world's ever-increasing need for food.
Cattle and pigs were first domesticated about 8,500 to 9,000 years ago. Through selective breeding, they have become main sources of animal food for humans. Dogs and horses have also been selectively bred for thousands of years. They have been bred for work and recreational purposes. This resulted in more than 150 dog breeds and 100 horse breeds.
Habitation or crossbreeding may involve combining different strains of a species or members of different species in an effort to combine the most attractive characteristics of both.For at least 3,000 years, female horses have been bred with male donkeys to produce mules, and male horses have been bred with female donkeys to produce whinnies, for use as work animals. Genetic engineering should definitely be used to alter the genetic makeup of true generations of humans. For example, if someone couldn't produce certain hormones or proteins, they could get gene therapy. First cells are removed from the person.Then in a laboratory, a virus is altered so that it cannot reproduce.
Next, a gene is inserted into the virus. After that, the altered virus is mixed with cells from the person (the cells from the person become genetically altered). Afterward, the altered cells are injected into the person. Finally the genetically altered cells produce the desired protein or hormone. This process helps make the human body function properly when it cannot by itself.
