This volume in the Milestones in Discovery and Invention set tells the stories of 14 of the most famous geneticists and genetic engineers who worked during the 50 years between the discovery of the structure of DNA (deoxyribonucleic acid, the chemical that proved to carry the "code" for an organism's inherited traits) in 1953 and the final reading out of the human genome, humanity's complete collection of genes, in 2003. James Watson and Francis Crick in effect began the modern era of genetics by working out DNA's structure, which showed how DNA molecules could reproduce and encode inherited information. Building on this discovery, Crick and others in the 1960s deciphered the individual chemical "letters" that make up the DNA code and showed how the code is used to make proteins, the substances that carry out most activities in cells.
In 1973, Herbert Boyer and Stanley N. Cohen showed that scientists could change genes, not only indirectly through breeding but directly through biochemical manipulations. Boyer and Cohen also moved genetic material from one organism to another and showed that the material produced its normal proteins in its new location. In doing so, they invented what came to be called genetic engineering. Boyer also pioneered the use of genetic engineering in industry, cofounding Genentech, the first biotechnology company.
Unlike Watson and Crick's discovery, genetic engineering quickly attracted the attention of nonscientists as well as scientists. Writers such as Jeremy Rifkin, the president of the Foundation on Economic Trends, warned that this new technology might create microbes that would cause unstoppable epidemics or other dangerous life-forms. Many later genetic engineering projects also drew criticism from ethicists, religious leaders, politicians, and others.
A few years after Boyer and Cohen's achievement, Michael Bishop and Harold Varmus revealed the genetic underpinnings of cancer, one of humanity's most feared diseases. Genes able to produce cancer in animals had been found in viruses, but Bishop and Varmus showed in 1976 that the genes did not originate in these infectious microorganisms. Instead, cancer-causing genes were normal cellular genes gone awry. Other researchers later found several kinds of cancer-related genes in human tumors, opening up the possibility of developing drugs that would counteract the genes' activity.
French Anderson explored a more direct approach to controlling genetic problems: repairing or replacing the defective genes themselves. In 1991, Anderson and his coworkers inserted normal genes for producing a key immune system chemical into blood cells of a child who suffered a rare inherited illness caused by lack of this chemical. This treatment, the first gene therapy given to a human, restored the young girl to health. Meanwhile, Nancy Wexler and others tried to identify the mutated genes that produced inherited diseases such as Huntington's disease, a brain-destroying ailment that afflicted Wexler's family. Cooperative effort among several research groups led to identification of the Huntington's gene in 1993. In that same year, Cynthia Kenyon identified genes in worms that lengthened the worms' lifespan, hinting that genetic changes underlay not only inherited illnesses but the much more common diseases associated with aging.
Few people opposed changing genes to prevent or treat inherited illness, but some worried that the kind of gene alteration pioneered by French Anderson might eventually be used to eliminate normal human variation or create "designer babies" that would be more like purchased products than natural children. The work of Ian Wilmut, who announced in 1997 that he had cloned a sheep from a mature adult cell, and of James Thomson, who reported in 1998 that he had isolated cells from human embryos (unborn living things in a very early stage of development) that might be used to create any tissue in the body, aroused similar concern about the implications that these scientific advances might have for humanity. For many commentators, both men's research raised the frightening possibility that human beings might be cloned, even though neither scientist supported such an activity.
German-Swiss scientist Ingo Potrykus, whose laboratory used genetic engineering in 1998 to create rice containing a nutrient that many children in the developing world lack, encountered a different type of controversy. Potrykus said he wanted the rice to be a weapon against malnutrition, but critics claimed that agricultural biotechnology companies planned to use the rice as a tool to force genetically modified foods on an unwilling world.
Perhaps the loudest debates of all have arisen about the implications of the Human Genome Project, a massive undertaking to determine the complete genetic makeup of human beings. During the project's final years, media attention focused on the rivalry between Francis Collins, who led the international, government-sponsored project, and scientist-entrepreneur Craig Venter, who headed a private company that claimed it could complete the genome analysis sooner and more inexpensively than the government effort could. Once the project was complete, however, discussion centered on the ways the genome information might be used. Observers say that understanding the human genome could lead to greatly improved treatments for disease, unprecedented discrimination based on genetic makeup—or perhaps both.
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