Editor's note: The following is the introduction to the May 2014 issue of Scientific American Classics: The Birth of the Great GMO Debate.

The idea of intentionally infecting a plant with a bacterium might seem strange. Just three decades ago, however, researchers discovered that they could use this infection to deliver new and potentially useful genes into crops. 

“What has long appeared to be simply the agent of a bothersome plant disease is likely to become a major tool for the genetic manipulation of plants: for putting new genes into plants and thereby giving rise to new varieties with desired traits,” announced acclaimed scientist Mary-Dell Chilton in 1983 in a pioneering article, one of many in this collection from the archives of Scientific American. Today genes introduced this way are yielding some of the most exciting new approaches to food security—as well as a hearty amount of debate.

Despite the excitement about the potential benefits of genetic engineering 30 years ago, the broader historical perspective highlighted in this collection reveals that this is just one of many thrilling and surprising advances in the long history of plant genetic alteration, which began well before this retrospective issue could document. (Scientific American extends back only to 1845.) Consider the assessment of the new technology of cross-pollination described in 1717 by botanist Richard Bradley: “A curious person may by this knowledge produce such rare kinds of plants as have not yet been heard of.”

For 10,000 years, in fact, we have altered the genetic makeup of our crops. For example, the ancient ancestor of modern corn was created some 6,000 years ago by Native Americans who domesticated a wild plant called teosinte, which looks nothing like a modern corn plant. If humans still depended on this wild relative, we would need hundreds, if not thousands, of times more plants—and acres—to replace corn. 

Today virtually everything we eat is produced from seeds that have been genetically altered in one way or another. The old approaches were crude and have been refined over the centuries. Modern methods include grafting and forced pollination (mixing genes of distantly related species) and radiation treatments to create random mutations in seeds. The newest method is genetic engineering—a technology developed after scientists observed that the “bothersome” plant pathogen Agrobacterium tumefaciens habitually introduced its own genes into plants. With a little laboratory work, the bacterium can instead implant desirable genes, such as those that increase nutrients or help the plant resist pests or drought. 

The planting of genetically engineered crops during the past 20 years has drastically reduced the amount of synthetic insecticides sprayed worldwide, shifted the use of herbicides to those that are less toxic, rescued the U.S. papaya industry from disease, and benefited the health and well-being of farmers and their families and consumers. Every scientific review of the crops on the market so far has concluded that the plants are safe to eat.

Just as the excitement surrounding the benefits of genetic engineering paralleled those of our predecessors, so, too, has the fear of plant tinkering technologies persisted over time. Consider the comments of Maxwell T. Masters, president of the International Conference of Hybridization, in his 1899 Scientific American article: “Many worthy people objected to the production of hybrids on the ground that it was an impious interference with the laws of Nature.” Today we are all too familiar with similar arguments about the application of genetic engineering in agriculture. 

This inspiring collection of articles reminds us that the technologies of plant breeding have always been controversial. Undoubtedly, new ways of producing crops—and the debates surrounding them—will continue. What is clear is that each new technology needs to be evaluated on a case-by-case basis and assessed for its environmental, economic and social impacts.

With the advent of cheap sequencing techniques, it is now much easier to isolate genes that will enhance sustainable farming practices than when Chilton was writing in the 1980s. Yet much remains to be done. Building on the success of the first generation of genetically engineered plants, scientists now are developing more robust staple food crops (including rice, banana, cassava, wheat and maize) for farmers in less developed countries, plants that use nitrogen more efficiently, and those that tolerate heat and salt—important goals as we contend with the need for local food security, a growing global population, polluted waterways and a changing climate.

The hybridization described by Masters in 1899 and the genetic engineering detailed by Chilton in 1983 are examples along a continuum of new technologies developed through human endeavor and creativity that have reduced the environmental impacts and increased the productivity of agriculture. Which one of these technologies is truly “appropriate”? There is no simple answer to this question. When the goal is a productive and ecologically based farming system, there are many interwoven nuances. 

As Masters noted more than 100 years ago: “We can only dimly perceive the enormous strides that gardening will make when more fully guided and directed by scientific investigations.”

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