The Issue at a Glance
Over the last century, medical research has arguably advanced human health more than all the previous 5,000 years combined. One statistic puts the change into perspective: Americans born in 1900 could expect to live an average of 49 years, but those born today will live an average of 77 years.
Much of the credit for that longer, healthier life span goes to medical discoveries such as insulin, antibiotics, blood pressure medications, and advanced surgery. Scourges such as polio and measles have been virtually eliminated in the U.S., and we have vastly increased our arsenal of treatments to fight AIDS and cancer.
Now deciphering the human genetic code promises a dramatic era of understanding, treating and preventing inherited diseases such as hemophilia and muscular dystrophy. But at the same time, advances in genetic research force us to address the social implications of being able to fundamentally alter our inner composition. Should researchers be allowed to tinker with our genetic codes, or create copies of human beings? Could we somehow be harming future generations by aiding sick people today?
DNA and destiny
In the summer of 2000, scientists announced they had cracked the code of the human genome, finding about 30,000 individual genes that guide human development. Already, medical researchers have identified hundreds of defects in the sequence of these genes that are "markers" for diseases.
More than 4,000 diseases have genetic causes. Unraveling the genome has heralded a new era for discoveries about how the body works and potentially how to make it work better. It allows patients to know whether they are at risk for certain diseases so they can take preventative measures. Eventually, doctors may actually be able to remove or alter specific genes to treat disorders or fix problems before they occur.
Now that science can identify the genes responsible for disease, the next frontier is manipulating genes for purposes of gene therapy, cloning and obtaining stem cells.
Gene therapy, where doctors attempt to repair someone's genetic code, is still in its infancy. Most of the experiments have so far been limited to replacing a defective gene with a healthy gene, which cannot be passed on to the patient's offspring. But scientists have also been actively discussing reprogramming human egg and sperm cells, not only treating the patient but passing on the changes to future generations.
Some scientists caution that fiddling with genes could have unintended consequences. For example, sickle cells, which cause sickle cell anemia, block certain kinds of malaria, so eliminating the cells might make some people less resistant to malaria. And no one knows what effect genetic tinkering will have on the gene pool a hundred generations from now. Others fear that parents might try to "design" their children to succeed or perhaps just to fit the fashion. Already there have been calls to ban such genetic manipulation, but supporters say that trying to impede one line of research could inadvertently hamper another.
But for the public and scientists both, the most dramatic advance in genetic research came from a Scottish sheep pen. An embryologist named Ian Wilmut stunned the world in 1997 when he introduced the first mammal cloned from an adult, Dolly the sheep, an exact genetic replica born of an experiment to create more productive farm animals.
Scientists in the United States, Italy and South Korea, among others, have publicly announced plans to produce the first human clone. Some of those most eager to explore human cloning are infertility specialists, who view it as another avenue to help their patients. A cloned baby would be an identical twin of one of the parents, only born years later. Still, many scientists around the globe (including Wilmut) have condemned even attempting a human clone as abhorrent, largely because 95 percent of animal cloning attempts fail, and most of those that come to term have severe deformities and die in a week or two. It took Ian Wilmut 277 failed attempts before Dolly was born. Many outside the scientific community have condemned the practice as unethical, and at least 24 nations as well as six U.S. states have banned human cloning.
For many scientists, the promise of medical technology lies with stem cells -- "master cells" capable of replicating indefinitely. That could give doctors the ability to create any body tissue, liberating people from the helplessness of waiting for an organ transplant and the risk of organ rejection. Stem cells are also highly promising for the treatment of ailments like Parkinson's or diabetes.