Philosophers and politicians will sometimes argue that an embryo prior to 8 weeks of gestation is not yet a human being, and suggest that early abortions, embryo experimentation, etc. should therefore be acceptable. The thalidomide drama of the late 1950's and early 1960's makes it clear that if women were not pregnant with a human being prior to 8 weeks of age, then taking a teratogen (causing embryo malformations) like thalidomide would not raise any concerns, since no human being would be present to be harmed by the drug. If there was no being that was human during the first trimester, then no disabilities would have occurred. But it is well known that the most drug-susceptible time during a pregnancy is the first trimester, specifically between the 4th and 7th week of gestation. Most of the children born without limbs were exposed to thalidomide during this time, when abortion advocates like to dissimulate and pretend that no human being is actually present.
Each human being arises at fertilization and exists as a biological continuum thereafter: at the joining of the sperm with the egg cell's membrane, a measurable depolarization occurs across that membrane that sets in motion a cascade of biochemical events and changes that will continue in a stepwise, uninterrupted fashion leading to the adult taxpayer. Meanwhile, the egg, if simply left to itself in the absence of sperm, will manage to live but for a few hours, and then die. Upon fusion with a sperm, however, the egg qua egg no longer exists, and an embryo, a human being at the earliest stage of his or her existence, genetically distinct from his or her mother, will be simultaneously engendered and launched onto the trajectory of "growing up," representing a new entity that can live for more than a hundred years. Such embryos are first nourished in the maternal womb, then at the maternal breast, then at the family dinner table and at fast food restaurants. Each of us is precisely such an embryo who has been allowed to grow up.
Father Tadeusz Pacholczyk, Ph.D. earned his doctorate in neuroscience from Yale and did post-doctoral work at Harvard. He is a priest of the diocese of Fall River, and serves as the Director of Education at The National Catholic Bioethics Center in Philadelphia. See www.ncbcenter.org