June 25, 2011 |
Dr. Robert Edwards won the Nobel Prize in 2010 for developing in vitro fertilization. The mixing of eggs and sperm in the test tube makes early human embryos, which can then be surgically placed in the uterus of the hopeful mother, where they develop into babies. This technology creates life, allowing otherwise infertile couples to bear children. About one percent of all births in the US are the result of in vitro fertilization. It also provides the foundation for the generation of designer genes babies, with pre-selected traits, and is therefore likely to become increasingly prevalent in the future.
But, in vitro fertilization results in hundreds of thousands of leftover embryos that are frozen indefinitely or discarded. Is the destruction of these early embryos, consisting of small clumps of cells, murder?
Early Human development takes place very slowly. The single cell that we all started from, the fertilized egg, divides once to make two cells, then again to make four, and once more to make a small cluster of eight cells. It takes a few days to get this far. And, amazingly, at this stage of development each of the eight cells is “totipotent”, or able to give rise to a complete and normal person if separated from the other cells. Accidental splitting of this clump is one way to make identical twins, triplets, etc.
A dictum of developmental biology is that “ontogeny recapitulates phylogeny”. This means that development of the individual reflects the evolution of its species. The Human embryo has a very long tail, and branchial arches that resemble gill slits. It first forms a primitive fish like kidney, which is later discarded and replaced with a mammalian kidney. Indeed, in many respects an early Human embryo more resembles a fish than a Human.
But, according to some, the embryo becomes a full person, with all rights, at the moment of conception, when the egg unites with the sperm. In some respects this is an attractive and clean answer. At this point there is the creation of a unique combination of genes that marks that individual and distinguishes it from all others. This is a physically well-defined event, setting apart those few eggs and sperm that do unite to form an embryo and then embark on the voyage of embryogenesis, to make a person.
There are, however, several arguments that suggest that the moment of conception is too early to confer full personhood. The fertilized egg has no beating heart, no brain, and no consciousness. It is not aware, it cannot think, and it cannot sense anything, including pleasure or pain. It is just two cells, the egg and sperm that have joined into one.
At the other end of life, when a person is old, sick and dying, we do have some established rules concerning when death has occurred, or when it is acceptable to “pull the plug”. Perhaps the same rules that apply to the end of life should be applied to the beginning. If the analysis of brain activity shows no conscious thought then life is considered over. This suggests that life begins with the formation of a brain and the initiation of conscious thought.
Then there is the question of the soul? It could be argued that while the fertilized egg has no brain, it nevertheless has a soul and is therefore a person. But if the early embryo has one soul, and then the embryo splits, do the resulting identical twins, triplets and so on only get a piece of the soul? And what about the reverse? Chimeras are people that look perfectly normal, but are the result of two early embryos fusing together to make one person. Do chimeras have two souls?
It is also interesting to note that there is an enormous natural loss of early Human embryos. The normal reproductive process is not very efficient. Only about half of Human fertilized eggs survive to birth. The vast majority of loss is very early, within the first few days after conception, and the mother never knew she was pregnant. This means that for every person alive, a total of about seven billion, there was a natural embryonic death. What a horrible holocaust, if we equate early embryonic life with that of an adult!
So, when is an embryo a person? The other extreme view might be at the moment of natural birth, when you enter the world and can breathe on your own. While some accept this view, for most it would be far too late. The vision of an abortion doctor strangling a late-stage abortus that is fighting for air is extremely repugnant. Clearly, when able to live outside of its mother given the support of available medical knowledge, with a functioning heart and brain, with pain and pleasure sensors, the baby in the mother is indeed a human being and deserving of the right to live.
Where do you draw the line? The one thing that is certain, is that there are no easy answers.
About the Author: Steve Potter, PhD, is a Professor of Pediatrics, in the Division of Developmental Biology, at Children’s Hospital Medical Center in Cincinnati. He has authored Designer Genes: A New Era in the Evolution of Man, published by Random House 2010. In addition he has written over one hundred science papers, and co-authored the third edition of the medical school textbook, Larsen’s Human Embryology.