The twentieth century is littered with the corpses of failed political ideas: colonialism, totalitarianism, communism, fascism, Maoism, and the dream of an Aryan master race. The century is also, perhaps less obviously, littered with failed scientific theories: Blondlot N-rays, the "steady state" universe, Lysenkoism, polywater, Freudian psychoanalysis, and cold fusion.

And then there are combinations of science and social ideas, which have fallen into disrepute or are today considered politically incorrect. I've already written in this column about two of these: lobotomies, and IQ testing. Today I want to discuss a third, one which is going to become a huge issue as the mapping of the human genome proceeds to completion.

I'm referring to eugenics. The word was coined in the nineteenth century, by Francis Galton. It means "well-born," and it is a perfect example of the slippery slope that leads from commonsense to social nightmare.

Galton had noticed that farmers for thousands of years had been improving plant and animal stock by selectively breeding from the best specimens. Francis Galton was a cousin of Charles Darwin, and like Darwin he believed in the survival of the fittest. Fittest, surely, meant the physically and the mentally superior. Human beings, like plants or animals, could therefore be improved by breeding from superior men and women.

So argued Galton, and so far this sounds logical and reasonable. Just common sense. But now look at the dark side of the argument. If humanity can improve itself by breeding from its best, surely it can also improve itself by preventing breeding by the worst. And who are these worst? To scientists and politicians considering the subject early in the twentieth century, that seemed like an easy question. The worst were the sickly, the mentally defective, the criminal, and even the "inferior races."

How could such people be discouraged from breeding?

Now we slide into the social nightmare. Since these inferior humans could not be relied upon to restrict their own breeding, it must not be left in their hands. There must be laws to sterilize the "unfit." Most countries in the western world introduced such laws. In 1927, in a famous case before the U. S. Supreme Court, that court ruled that compulsory sterilization of certain classes of citizens was within the right of individual states. Fifteen states had such laws on their books. In writing its opinion, the Supreme Court delivered this verdict: "Three generations of imbeciles are enough." Ten years later, Nazi Germany was applying the "unfit" designation to justify the sterilization (and later the murder) of the mentally retarded, and then of psychiatric patients, gypsies, Negroes, and Jews.

Eugenics had begun with extraordinary support from many of the most prominent figures of the day. Theodore Roosevelt approved of it, as did George Bernard Shaw, Oliver Wendell Holmes, H.G. Wells, and Winston Churchill.

The horrors that were performed by invoking the name of eugenics before and during the Second World War ended that support. No one talks any more about eugenics, except as a dreadful example of a failed social policy.

We do, however, practice it. If a human embryo happens to have an extra copy of Chromosome 21, the child will suffer from what is known as Down's syndrome, more colloquially termed Mongolism. Such children have a reduced life expectancy and are slightly mentally retarded. The chance that a mother will bear such a child increases rapidly with age, from one in twenty-three hundred for a mother of twenty, to one in a hundred for a mother of forty. An amniocentesis test can readily determine, early in pregnancy, whether or not the developing fetus has Down's syndrome. Older mothers are often encouraged to take the test. There is only one logical reason for doing so. Although it is frequently not stated unless the Down's syndrome test is positive, the parents of such a child may be encouraged to abort it.

Down's syndrome is just a beginning. The mapping of the human genome will provide a torrent of tests applicable to developing embryos. Huntington's chorea, a terrible degenerative disease with a strong hereditary component, is known to be linked to a specific gene sequence on Chromosome 4. At the moment, this disease is incurable, but tests exist to determine if a particular person will develop it. A positive result for such a test of an embryo might persuade many parents to consider abortion.

As another example, Tay-Sachs disease and cystic fibrosis are incurable disorders that affect primarily Jewish people. Rather than testing a developing embryo, which is already too late, there is in the United States a committee, which will trace the bloodlines of people considering marriage. If both bride and groom are carriers for the mutation that causes Tay-Sachs or cystic fibrosis, the committee advises against the marriage.

As we unravel the genetic code, we discover more and more places that form the loci for particular disorders. These range from potentially or certainly fatal diseases, such as Huntington's chorea and sickle cell anemia, to more minor nuisances such as lactose intolerance, allergies, or an inability to digest alcohol. Chances are, we all have a genetic tendency to some ailment, though we usually have no idea what it is.

Now for the difficult question. As our knowledge and the sophistication of our medical tests increase, we will have to make decisions that never troubled our ancestors. A century ago, no one could do anything about a Down's syndrome child, or a Tay-Sachs child. It was in the hands of God. A baby was born, and you as a parent did your best.

Today, regardless of what we call it, parents are increasingly in a position to practice eugenics. Genetic mapping of mother and father can tell the odds that a child, if they choose to have one, will suffer certain disorders. Genetic testing of an embryo can provide definitive proof as to whether or not the developing child will surely be born carrying those disorders.

And now we return full circle, to ask what the rights, responsibilities, and duties of government should be, versus the rights, responsibilities and duties of parents; and, last but perhaps most important of all, what are the rights of the unborn?

I don't pretend to have answers. I don't even have knowledgeable opinions. What I do know is that progress in genetic science will make eugenic questions as much a matter for debate in the first decades of this century as they were in the first decades of the last one. And this time around, the number of difficult decisions will be far greater.

"Borderlands of Science" is syndicated by: