Whether the fundamental question is seen as a woman's right to control her body or a fetus's right to be born, abortion has become one of the most explosive and divisive issues in America today. The Supreme Court ruled in 1973 that women have a constitutional right to an abortion for at least the first six months of pregnancy, and ever since then opponents of abortion have sought legal ways to blunt the ruling. They have succeeded in slashing federal funding for abortions. Now they are pressing in Congress the Human Life Statute, co-sponsored by Sen. Jesse Helms (R-N.C.) and Congressman Henry Hyde (R-III.). By defining the human embryo as "actual human life," the Helms-Hyde Bill would extend to fetuses the 14th Amendment protection against depriving "any person of life, liberty or property without due process...[or] equal protection of the laws." Abortion would be halted and, opponents contend, so would some types of contraception and many new forms of genetic research. As professor of biology and public policy at the University of California at San Diego, Clifford Grobstein ponders the issues of human life almost daily—and last month he visited Capitol Hill to testify about the implications Helms-Hyde could have. A former dean of the Medical School and vice-chancellor of Health Sciences at UCSD, Grobstein, 64, is the author of A Double Image of the Double Helix (on recombinant DNA) and the newly published From Chance to Purpose: An Appraisal of External Human Fertilization (Addison-Wesley, $17.50). Grobstein recently elaborated on the scientific and moral issues Helms-Hyde raises for Nancy Faber of PEOPLE.

Is Helms-Hyde correct in stating that "scientific evidence indicates a significant likelihood that actual human life exists from conception"?

In my view, no. Human life began a very long time ago and has been continuous ever since. Life does not "begin" at conception because, for one thing, the egg and the sperm are already both living. The cells that give rise to the egg and the sperm are also living.

Is that so different from what the bill says?

The implications are very different. I do not see the moment of conception as having the same significance the bill's sponsors do. When the sperm fertilizes the egg, genetic material from each parent is brought together, endowing a new generation with a unique combination of hereditary traits. Fertilization is a step in the continuum of life. It is not an event precisely defining a new individual in the usual social and legal sense.

How do you define an "individual"?

That is exactly the difficult question we face. Scientifically, it is not nearly as simple as the Helms-Hyde Bill suggests.

Would you explain?

The fertilized egg—or zygote, in biological terms—can give rise to something more or less than one whole individual. It may develop in a grossly abnormal way, for instance, and lack a head, limbs or other major body parts. Or it can split to form identical twins. So even though the zygote is hereditarily unique, it isn't yet fixed as a new single and complete human being.

Doesn't cell division rapidly clarify the picture?

It depends on what you consider rapid. By the second or third day after fertilization, the embryo has divided into about eight cells. But they are simply an undifferentiated mass. In certain animal species, in fact, cells at this stage are so alike from one embryo to another that scientists have successfully interchanged them. After about the third day—in humans—the cells band together more tightly in a process known as compaction. This may be when the process of becoming an individual starts.

Why the doubt?

The embryo is still not fully stabilized. As late as two weeks after fertilization, when the embryo has already embedded itself in the wall of the uterus, where it will gestate, twinning can still occur. And there's another problem with saying the earliest embryo is an individual. Only a portion of the cells in the embryo develops into a baby. The others become the placenta, the umbilical cord and membrane, and are discarded at birth.

What happens after the embryo has "stabilized" in the second week?

We can then say a singleness occurs, but we still don't have the characteristics associated with a human being—there are no eyes, for instance, no legs, no head.

Can the fetus at this stage feel pain?

The nervous system doesn't form until well after the second week. People who study such things say pain is associated with electrical activity in nerve cells and the synthesis and breakdown of certain enzymes, among other things. All signs indicate this type of function is absent at least through the first eight to 10 weeks. Even at some later stages, we're uncertain whether the fetus can feel discomfort or pain.

When would you finally confer person-hood on a fetus?

Though the early stages of fetal development clearly belong to a different category than the late stages, the exact borderline simply can't be determined on scientific or technical grounds. Maturation is already recognized as a valid factor to consider when conferring rights. For instance, we protect infants against loss of life, but we don't let them vote. The Helms-Hyde Bill, however, would give an embryo at any stage rights equivalent to those of a person. I'm concerned that by focusing on just one purpose—protecting the fetus's life—we may sacrifice other purposes and lose more than we gain.

Obviously, abortion would be considered murder under Helms-Hyde. Does that trouble you?

As a scientist providing reliable information, I'm neither pro-abortion nor anti-abortion. We don't know enough either to ban abortion totally or allow it without the current constraints in the last three months of pregnancy.

Wouldn't external, or so-called test-tube, fertilization also be threatened?

It would because more than 90 percent of the eggs surgically removed from the mother's ovary are lost after external fertilization. If those embryos had full rights, it would amount to manslaughter or, conceivably, murder. One in every 500 women has a blocked oviduct and thus could benefit from this technique. But this increasingly promising means of overcoming sterility would be severely limited.

What would be the effect on contraception?

The intrauterine device, which can prevent the fertilized egg from implanting itself in the uterus, could be ruled illegal. So could morning-after pills, which act on already fertilized eggs.

Would research with human embryos be affected?

Undoubtedly. Very little is known now about the effect on the human embryo of steroids, antibiotics or other drugs, or of common substances like caffeine, alcohol or indoor pollutants. These may cause birth defects. But it's hard to draw accurate conclusions about humans from studies limited to animal embryos.

Should any limits be put on experiments with human embryos?

Absolutely. Decisions like this are the business of elected officials. My concern is to bring clear scientific information to bear on the problems. I know that some people worry that with genetic engineering and external fertilization, people could choose the sex of their baby, potentially increasing the number of male over female births two to one, or that castes would be created of individuals engineered for menial chores. I'm not sure how much of this will be scientifically possible. There's also a lot of fear about cloning, but any human applications would be expensive, complicated—assuming it could even be done—and unpredictable. I am not clear why it is even talked about as attractive. Even identical twins don't grow up "identical."

Is Washington really coming to terms with these new genetic issues?

In the late 1970s the Ethics Advisory Board of the Department of Health, Education and Welfare suggested that the government fund research on the safety and efficacy of external fertilization. But that was never acted on. The policy indecision in part stems from the very emotional nature of the questions, especially the abortion question.

How should the issues be addressed?

I would like to see a special federal commission set up to make continuing policy recommendations on intervention in human heredity and development. The panel should include scientific, medical and lay people, and it should have a global focus. I would suggest a few principles that it might be guided by. First, to preserve and not change humanity. Second, to correct and eliminate the most obvious birth defects and disabling diseases. Third, to do nothing that would reduce human potential. There could be others, but these will signal our concern for our species and help us preserve our sense of human kinship.