If human eggs are destroyed, no one seems to be concerned. Possibly because very few human eggs result in a child. Of the up to 2 million oocytes (immature eggs) that each human female is born with, only about 400 will mature and be ovulated. For each monthly cycle, about 20 cells begin the process to become a mature egg, but only one or two will complete the process. By the way, this maturation process for each egg begins about 100 days before ovulation.
If human sperm are destroyed, no one gets concerned. Even more sperm are produced than eggs, so the chances of any sperm resulting in a child are minuscule.
Once a sperm and an egg are joined, commonly called conception, many people call the merged cells a human. While estimates vary, the chances of a fertilized egg resulting in a live child are only about 33%. Natural events end the process for most fertilized eggs before they are implanted. One can conjecture that many women who are "late" really are pregnant, but the process is halted naturally very early.
Once implantation occurs (the egg is implanted in the uterus about the 6th day after fertilization), the embryo at this point has about a 66% chance of surviving to birth.
The process of human development is very complicated. There are many problems that can interrupt the process before the birth of a live child.
We have an on-going ethical debate about when life begins. Why is it that an egg or a sperm is not seen as human life, but a fertilized egg is? None of the three can result in a child by themselves. At the minimum, the fertilized egg must be implanted in the uterus. This would argue that cells in a petri dish are not human. Yes, those cells could be implanted and result in a child, but an egg could be fertilized with a sperm in a petri dish and then implanted. If the embryo in a petri dish is human life, then the egg and sperm in their petri dishes are also human life. Of course, that is absurd.
Since invitro fertilization and some birth control methods routinely kill fertilized eggs, a belief that human life starts at fertilization not only is not supported by natural events, it would cause many people to be labeled murders.
When life begins is an ethical question, not a scientific one. But science shows us that for those who believe human life starts very early in the process, implantation is a more logical starting point than fertilization.
Cartoon used with permission.
For more information on the latest science on human reprodcution, see the article
The Good Egg, printed in Discovery magazine, May, 2004.
