Zygotes and People Aren’t Quite the Same

April 25, 2002

HANOVER, N.H. When President Bush convened his advisory panel on bioethics in January, he told those of us serving on it to engage in that age-old technique of intellectual exploration called debate. “That’s what I want,” he said. “You haven’t heard a debate until you have heard Colin Powell and Don Rumsfeld go at it.”
So “it was a surprise when, on April 10, the president announced his decision to ban cloning of all kinds. His opinions appeared fully formed even though our panel has yet to prepare a final report and will be voting on the crucial point of biomedical cloning — which produces cells to be used in researching and treating illnesses. While it is true that the president’s position is one held by some of the members of the panel, not all agree.
Most people are now aware that medical scientists put cloning in two different categories. Biomedical cloning is distinct from reproductive cloning, the process by which a new human being might be grown from the genetic material of a single individual. At this point, no scientist or ethicist I know supports reproductive cloning of human beings. The debate is solely about biomedical cloning for lifesaving medical research.
Scientists prefer to call biomedical cloning somatic cell nuclear transfer, because that is what it is. Any cell from an adult can be placed in an egg whose own nucleus has been removed and given a jolt of electricity. This all takes place in a lab dish, and the hope is that this transfer will allow the adult cell to be reprogrammed so that it will form a clump of approximately 150 cells called a blastocyst. This will be harvested for the stem cells it contains.
At this point we encounter a conflation of ideas, beliefs and facts. Some religious groups and ethicists argue that the moment of transfer of cellular material is an initiation of life and establishes a moral equivalency between a developing group of cells and a human being. This point of view is problematic when viewed with modern biological knowledge.
We wouldn’t consider this clump of cells even equivalent to an embryo formed in normal human reproduction. And we now know that in normal reproduction as many as 50 percent to 80 percent of all fertilized eggs spontaneously abort and are simply expelled from the woman’s body. It is hard to believe that under any religious belief system people would grieve and hold funerals for these natural events. Yet, if these unfortunate zygotes are considered human beings, then logically people should.
Moreover, the process of a single zygote splitting to make identical twins can occur until at least 14 days after fertilization. Also, divided embryos can recombine back into one. How could we possibly identify a person with a single fertilized egg?
Modern scientific knowledge of the fertilization process serves as the basis for the British government’s approval of biomedical cloning and embryo research. Britain does not grant moral status to an embryo until after 14 days, the time when all the twinning issues cease and the embryo must be implanted into the uterus to continue developing.
The blastocyst, the biological clump of cells produced in biomedical cloning, is the size of the dot on this i. It has no nervous system and is not sentient in any way. It has no trajectory to becoming a human being; it will never be implanted in a woman’s uterus. What it probably does have is the potential for the cure of diseases affecting millions of people.
When I joined the panel, officially named the President’s Council on Bioethics, I was confident that a sensible and sensitive policy might evolve from what was sure to be a cacophony of voices of scientists and philosophers representing a spectrum of opinions, beliefs and intellectual backgrounds. I only hope that in the end the president hears his council’s full debate.
Dr. Michael S. Gazzaniga is director of the Center for Cognitive Neuroscience at Dartmouth College.