Answer:
Through out history people have artificially selected plants and animals to breed. These people selected plants with the traits they desired for plants and animals and this is a form of genetic engineering. By doing this they where able to choose plants and animals that grow faster, yield higher amounts of food, grow in more extreme environments, and are more resistant to disease and pests. Our early human ancestors used these techniques to make food production efficient enough to be able to move away from the hunter gatherer life style and live in permanent settlements resulting in the beginning of human civilization. Recently besides just breeding better plants for human cultivation we have been able to directly delete, modify, and add genes to plants. The goals our however are largely the same with the exception of many modification being made to make our crops resistant to herbicides and pesticides allowing us to use these chemicals in fields containing our food crops. All of these techniques are ultimately used to produce more food more cheaply. Recently some genetic engineering has also been used to cause plants and animals used in agriculture to produce specific nutrients like vitamin A in rice or specific drugs.