To understand the uproar over GMOs, one must first understand the science behind genetic engineering. Without that baseline, most conversations about GMOs quickly devolve into shouting fests between stereotyped extremes. For starters, genetic engineering is nothing new. Humans have been crossbreeding different plant varieties for millennia, a practice that, over generations of people and plants, has enabled farmers to successfully develop crops from corn to tomatoes that are bigger, tastier, and more resistant to disease. Such trait refinement, and the trial and error required to pull it off, are essential to agriculture, and this practice of modifying the genetic makeup of a crop plant is as organic as they come.

In conventional breeding, two types of a plant, let’s say two types of corn, are crossed, with the hope that their offspring will be a new and improved variety. This breeding approach is a bit like playing the slots. But by the mid-20th century, we got better at breeding thanks to two developments: irradiation and, later, gene splicing. Irradiation—walloping the genome of an organism with radiation—speeds up the rate of random DNA mutation, in effect, pulling the handle of the slot machine more quickly. In a 2005 paper published in Nature Biotechnology, Strauss and his co-authors point out that more than 2,200 crop varieties are on the market “that had an irradiation-induced mutation step in their pedigrees.” Yet none of these crop varieties—Rio Red seedless grapefruit, semi-dwarf rice, high-oleic sunflower seed—are considered GMOs by opposition groups, government regulators, or your local supermarket, even though these crops’ genes have been dramatically modified by humans.

So what exactly is a GMO? It’s the product of a specific technique. In the past few decades, scientists have learned how to cut and paste genes with remarkable precision. This ability is the essence of genetic engineering (aka gene splicing or recombinant DNA technology). What makes this breeding method powerful, and distinct from irradiation, is that it removes the guesswork. More critically, scientists can now transfer DNA not just between similar plants, but also between organisms that would otherwise never reproduce, which is to say mix their DNA, on their own.

For example, in the case of one type of genetically modified corn, the plant is armed with a protein toxic to a certain crop pest. The chance that corn could ever acquire this defensive ability by way of random DNA mutation is minuscule, according to Mace Vaughan of the Portland-based Xerces Society, an invertebrate conservation organization that often deals with pest issues. “It’s less likely, even, than a roomful of chimpanzees ever typing out a Shakespeare sonnet,” he says.

But the way in which GM corn or any other transgenic plant is developed doesn’t make an organism hazardous. Thus far, in fact, the evidence is to the contrary. We have been consuming GM foods for more than a decade, and a mountain of studies about possible health consequences have to date revealed no threat or harm to human health.

Today, more than 150 million acres of farmland in the United States are planted with GM corn, soy, cotton, squash, papaya, alfalfa, sugar beet, and canola, and an estimated 70 percent of all products on supermarket shelves nationwide contain at least some GM ingredients, such as corn syrup or canola oil. And although amber waves of GM grain may conflict with our Michael Pollan–inspired fantasy of little family farms everywhere, GMOs may be greener than you think. The journal AgBioForum has estimated that GM crops reduce pesticide use by nearly 250,000 tons, and can also help reduce greenhouse gas emissions, because farmland planted with them requires less tilling. Less tilling means more carbon dioxide remains locked in the ground, and diesel tractors spend less time spewing exhaust.