After thirty years of investigation into cell genetics, researchers made startling discoveries in the 1960s and early 1970s which culminated in the development of processes, collectively known as recombinant deoxyribonucleic acid (rDNA) technology, for the active manipulation of a cell's genetic code. The technology has created excitement and controversy because it involves altering DNA – which contains the building blocks of the genetic code. Using rDNA technology, scientists can transfer a portion of the DNA from one organism to a single living cell of another. The scientist chemically "snips" the DNA chain of the host cell at a predetermined point and attaches another piece of DNA from a donor cell at that place, creating a completely new organism. Proponents of rDNA research and development claim that it will allow scientists to find cures for disease and to better understand how genetic information controls an organism's development. They also see many other potentially practical benefits, especially in the pharmaceutical industry. Some corporations employing the new technology even claim that by the end of the century all major diseases will be treated with drugs derived from microorganisms created through rDNA technology. Pharmaceutical products already developed, but not yet marketed, indicate that these predictions may be realized. Proponents also cite nonmedical applications for this technology. Energy production and waste disposal may benefit: genetically altered organisms could convert sewage and other organic material into methane fuel. Agriculture might also take advantage of rDNA technology to produce new varieties of crops that resist foul weather, pests, and the effects of poor soil. A major concern of the critics of rDNA research is that genetically altered microorganisms might escape from the laboratory. Because these microorganisms are laboratory creations that, in all probability, do not occur in nature, their interaction with the natural world cannot be predicted with certainty. It is possible that they could cause previously unknown, perhaps incurable diseases. The effect of genetically altered microorganisms on the world's microbiological predator-prey relationships is another potentially serious problem pointed out by the opponents of rDNA research. Introducing a new species may disrupt or even destroy the existing ecosystem. The collapse of interdependent relationships among species, extrapolated to its extreme, could eventually result in the destruction of humanity. Opponents of rDNA technology also cite ethical problems with it. For example, it gives scientists the power to instantly cross evolutionary and species boundaries that nature took millennia to establish. The implications of such power would become particularly profound if genetic engineers were to tinker with human genes, a practice that would bring us one step closer to Aldous Huxley's grim vision in Brave New World of a totalitarian society that engineers human beings to fulfill specific roles.