The term genetic engineering refers to technologies that modify genes. Unlike selective breeding, which merely chooses traits that are already found in nature, genetic engineering acts directly on the genetic material itself in order to alter an organism's traits. Genetic engineering is the cornerstone of modern biotechnology, and through it human beings have the power to modify the molecular basis of all forms of life.

A brief history

The concept of genetic engineering emerged in the 1960s and was first realized in the 1970s. Its development depended upon a century of advances in science, beginning in the 1860s with Gregor Mendel's discovery of the existence of factors that govern inheritance. In the 1940s, it was learned that these factors, now called genes, are composed of a complex molecule, deoxyribonucleic acid or DNA. In 1953, Francis Crick and James Watson described the structure of DNA as the famous double helix along which are found pairs of chemicals. Soon it was learned that the sequence of these chemicals, known as bases, carries information that instructs the cell how to make proteins that are essential to the structure and function of the cell.

By the 1960s, it was becoming clear that scientists would soon learn how to manipulate this chemical information and thereby engineer genes. In the ensuing decades, various techniques for manipulating DNA have been developed, beginning in the early 1970s with the discovery of the use of restriction enzymes, which exist in nature and which cut and join strands of DNA at precise locations. This allows scientists to cut and splice DNA. A later discovery called polymerase chain reaction (PCR) made it possible for researchers to produce huge quantities of specific DNA sequences. Further advances in the use of computers to decode, store, and manipulate DNA means that researchers can discover and modify DNA on a broad scale and with considerable precision.

Methods

Genetic engineering uses various methods in pursuit of many goals. One method is to transfer a gene from one organism to another. For instance a human gene may be transferred to a microorganism in order to develop a new strain of microorganism that will produce a human protein, such as insulin, for pharmaceutical purposes. Much of the insulin used by diabetics comes from this process. It is possible in fact to transfer many genes into an organism by packaging them together as a kind of artificial chromosome, sometimes called a gene cassette. Plants, too, are genetically engineered to produce pharmaceutical products, to enhance their protein value as foods, to allow them to grow with less reliance on pesticides or fertilizers, to resist freezing or spoiling, to enhance flavor, or perhaps to grow in seawater. Another method is to incapacitate a particular gene by deliberately causing it to mutate and shut itself down. For instance if scientists know that an impaired human gene is linked to a disease such as cancer, they will find the corresponding gene in laboratory rats, shut it down, and create a strain of rats with this gene knocked out, and therefore with a high likelihood for cancer, in order to have animals on which to test possible therapies.

In human beings, scientists have attempted to modify or replace genes in some of the cells of patients' bodies in order to treat diseases with genetic basis. This strategy, called gene therapy, began in 1990 with mixed success. In time it will likely become widely used to treat a variety of diseases. Still another method is to modify a tiny portion of the gene—one or two bases of DNA—by constructing a special small molecule that can trigger what is called a mismatch repair. Ordinarily the body corrects for the mutations that occur naturally inside the body all the time, and scientists are learning how to exploit the body's own repair mechanisms to correct mutations that may have been inherited. These strategies used so far on human beings differ sharply from what scientists are attempting to do with other animals. In human beings, researchers are attempting to change the genes only in selected cells that are affected by the disease. In animals, however, the modifications affect every cell and are passed on to future generations. That strategy, often called germline modification, has been proposed for use on human beings but remains controversial from the standpoint of safety.

Religious concerns

From the time genetic engineering was first considered in the 1960s, religious scholars and institutions have commented on its value and limits. Often scientists themselves, not to mention science journalists, report on developments in genetics in religious terms, speaking of DNA as the mystery of life or the human genome as the holy grail of biology. Not surprisingly, the general public sometimes responded to these developments with religious fervor, sometimes in favor of them, but often opposed to developments that people saw as, for instance, playing God.

One concern of special importance to many religious scholars and leaders has been the use of the system of patenting, by which governments give exclusive rights for a time to inventors, to protect developments in genetics. Particularly troubling has been the granting of patents to gene sequence information. Many have argued that knowledge of genes is discovery, not invention, and should not be eligible for patent protection. Many have also argued that granting biological patents amounts to patenting life, therefore making life a mere commodity. Other religious scholars recognize that patenting, while not perfect, is essential to the financial development of the full potential of genetic engineering, and that opposition to patenting is tantamount to opposing the benefits of research.

Beyond these general concerns, many religious scholars and organizations have considered developments in genetic engineering on a case-by-case basis. For instance, many religious organizations have responded to the use of genetic engineering to modify food by recognizing its potential for increasing the quality and quantity of food, but with cautions having to do with the viability of small farms, global inequities, the power of corporations in view of intellectual property rights, and the right of consumers to know what they are eating. Similarly, religious scholars have raised concerns, but generally have not objected categorically, to genetic engineering of animals. Of special concern is the prospect of herds of genetically identical livestock becoming vulnerable to disease, or to the use of genetic engineering to create strains of animals whose sole purpose is to suffer a disease for the benefit of medical research.

Quite understandably, human applications evoke the most intense religious responses. Religious responses to the use of genetic engineering for pharmaceutical purposes have been positive, with concerns limited to patenting, to the high costs of medicines, and to the need for socially just patterns of distribution. Furthermore, almost without exception, human gene therapy has met with approval not just by the public, but by religious institutions and scholars, who assess it morally as an extension of traditional medicine. Issues of safety remain, and many are concerned that the technique, when shown to be beneficial, will not be justly distributed.

The greatest concern, however, is that the technique will not be limited in its application to therapy but will be used for enhancement of human health and possibly of traits that are unrelated to health. Those who voice this concern point not just to cosmetic surgery and to performance enhancing drugs in sports but to the use of mood-altering pharmaceutical products, such as the drugs known as selective serotonin reuptake inhibitors (SSRIs). Evidence exists that people request these drugs not to treat anxiety or depression but to improve their mood and thus their performance in life. If that is true, some argue, how much more will people request gene modification that enhances their state of being and their performance. As of 2002, it is not at all clear which human traits will become susceptible to enhancement by genetic engineering. Height, most definitely, will be modifiable, but perhaps mental and emotional traits may be modifiable too. The concern here is the lack clarity about the distinction between therapy and enhancement, and thus the lack any publicly credible way to prevent those with economic or political means from acquiring new ways to improve themselves to the competitive disadvantage of others.

Sometime in the twenty-first century, many believe, humans will learn how to modify the genes of their offspring. Such germline modification, as it is usually called, is already done in other mammals, although not reliably. Many technical obstacles lie ahead, but learning to do this in human beings has a strong attraction, for some, in the promise that a family might be freed of a genetic disease that has afflicted it for generations. Other techniques, such as testing an embryo for disease before it is implanted, will probably achieve the same result at less cost and risk. If so, it may turn out that the real advantage of germline modification is not to eliminate disease but to improve the next generation, perhaps by enhancing resistance to disease or by producing other traits. The prospect of children born with such enhancement, often referred to as designer babies, is widely opposed by the general public, secular scholars, and religious leaders, even though most analysts concede that it probably cannot be prevented.

Religious objections to germline modification are that the resulting children will enter the world as objects, engineered according to the will of their designers and not as persons who emerge from the love of their parents. The intrusion of technology perverts the relationship between parent and child, difficult under any circumstance, but all the more so if parents can use technology to express their desires for the kind of child they want to have. Others believe that designed children will face impossible expectations in achieving that for which they are designed, and that they will likely resist their makers' intentions.

See also BIOTECHNOLOGY; CLONING; DNA; EUGENICS; GENE PATENTING; GENE THERAPY; GENETICALLY MODIFIED ORGANISMS; GENETICS; HUMAN GENOME PROJECT; PLAYING GOD; STEM CELL RESEARCH

RONALD COLE-TURNER