What Is Genetic Modification?

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Genetic modification is the process of altering the genetic makeup of an organism. This has been done indirectly for thousands of years by controlled, or selective, breeding of plants and animals. Modern biotechnology has made it easier and faster to target a specific gene for more-precise alteration of the organism through genetic engineering.

The terms “modified” and “engineered” are often used interchangeably in the context of labeling genetically modified, or “GMO,” foods. In the field of biotechnology, GMO stands for genetically modified organism, while in the food industry, the term refers exclusively to food that has been purposefully engineered and not selectively bred organisms. This discrepancy leads to confusion among consumers, and so the U.S. Food and Drug Administration (FDA) prefers the term genetically engineered (GE) for food.

A brief history of genetic modification

Genetic modification dates back to ancient times, when humans influenced genetics by selectively breeding organisms, according to an article by Gabriel Rangel, a public health scientist at Harvard University. When repeated over several generations, this process leads to dramatic changes in the species.

Dogs were likely the first animals to be purposefully genetically modified, with the beginnings of that effort dating back about 32,000 years, according to Rangel. Wild wolves joined our hunter-gatherer ancestors in East Asia, where the canines were domesticated and bred to have increased docility. Over thousands of years, people bred dogs with different desired personality and physical traits, eventually leading to the wide variety of dogs we see today.

The earliest known genetically modified plant is wheat. This valuable crop is thought to have originated in the Middle East and northern Africa in the area known as the Fertile Crescent, according to a 2015 article published in the Journal of Traditional and Complementary Medicine. Ancient farmers selectively bred wheat grasses beginning around 9000 B.C. to create domesticated varieties with larger grains and hardier seeds. By 8000 B.C., the cultivation of domesticated wheat had spread across Europe and Asia. The continued selective breeding of wheat resulted in the thousands of varieties that are grown today.

Corn has also experienced some of the most dramatic genetic changes over the past few thousand years. The staple crop was derived from a plant known as teosinte, a wild grass with tiny ears that bore only a few kernels. Over time, farmers selectively bred the teosinte grasses to create corn with large ears bursting with kernels.

Beyond those crops, much of the produce we eat today — including bananas, apples and tomatoes — has undergone several generations of selective breeding, according to Rangel.

The technology that specifically cuts and transfers a piece of recombinant DNA (rDNA) from one organism to another was developed in 1973 by Herbert Boyer and Stanley Cohen, researchers at the University of California, San Francisco, and Stanford University, respectively. The pair transferred a piece of DNA from one strain of bacteria to another, enabling antibiotic resistance in the modified bacteria. The following year, two American molecular biologists, Beatrice Mintz and Rudolf Jaenisch, introduced foreign genetic material into mouse embryos in the first experiment to genetically modify animals using genetic engineering techniques.

Researchers were also modifying bacteria to be used as medications. In 1982, human insulin was synthesized from genetically engineered E. coli bacteria, becoming the first genetically engineered human medication approved by the FDA, according to Rangel.

Genetically modified food

There are four primary methods of genetically modifying crops, according to The Ohio State University:

  • Selective breeding: Two strains of plants are introduced and bred to produce offspring with specific features. Between 10,000 and 300,000 genes can be affected. This is the oldest method of genetic modification, and is typically not included in the GMO food category.
  • Mutagenesis: Plant seeds are purposely exposed to chemicals or radiation in order to mutate the organisms. The offspring with the desired traits are kept and further bred. Mutagenesis is also not typically included in the GMO food category.
  • RNA interference: Individual undesirable genes in plants are inactivated in order to remove any undesired traits.
  • Transgenics: A gene is taken from one species and implanted in another in order to introduce a desirable trait.

The last two methods listed are considered types of genetic engineering. Today, certain crops have undergone genetic engineering to improve crop yield, resistance to insect damage and immunity to plant diseases, as well as to introduce increased nutritional value, according to the FDA. In the market, these are called genetically modified, or GMO crops.




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