Human embryos: potential humans?

Abstract

Carl Feldbaum's Policy Forum “Some history should be repeated” ( Science 's Compass, 8 Feb., p. [975][1]) demonstrates several common conceptual errors in the debate on cloning [or somatic cell nuclear transfer (SCNT)]. To say that an embryo has the “potential” to become a human being is dangerous. A sperm has the potential to become a human being, as does an oocyte. The human zygote, however, is more than merely “potentially” a human being. If a human embryo only has the potential to become a human being, then when precisely does the embryo become a human being? There is no more pivotal point in the biologic growth and development of a human than the moment of fertilization when 23 chromosomes from the mother join with 23 chromosomes from the father to form a new, genetically unique individual. Similarly, in cloning, what stages of development impart “more” humanity to an embryo than the moment that the SCNT transfer stimulates an oocyte to divide? Perhaps more dangerous is the concept that it is not a precise moment, but a gradation of human worth. With this model, a fetus at 3 months is somewhat of a human being, but a newborn is more of a human being. So is a 10-year-old more of a human being than a 1-year-old? Is a politician or athlete more of a human being than a wheelchair-bound paraplegic? Can we really stratify intrinsic human dignity and worth? Is human equality a myth? This sort of thinking forms the basis for demeaning entire classes of people, ultimately denying them their humanity. The 20th century has not been without ample evidence of the depravity of such thinking. Some history surely should not be repeated. Furthermore, it is an error to contend, as Feldbaum does, that it is a “faith-based belief that the cloned embryo's potential to become a person entitles it to legal and moral status as a person.” No, the intrinsic dignity of a human person is not “faith-based”; it is a truth grounded in natural law, not theological exegesis. It is not a faith-based belief that a human embryo's potential to become a person entitles it to legal and moral status. It is a part of the fabric of natural law that the human embryo's actuality of being human entitles him or her to legal and moral status. # Response {#article-title-2} Ultimately, science cannot win an argument with those who look at a sick person and a microscopic cluster of undifferentiated cells side by side and see the same thing: two human beings. But most people, regardless of religious or scientific background, intuitively recognize a difference between the two, as well as the gradations in development that Baumgartner finds so disturbing. Baumgartner asks, “If a human embryo only has the potential to become a human being, then when precisely does the the embryo become a human being?” I cannot answer that question, although some scientists have suggested that the appearance of the primitive streak is an important demarcation. Implantation in the uterus is an important step as well, and that is where federal legislation that the biotechnology industry supports would draw the line. The accusations of eugenics—particularly against the disabled—are inappropriate, given that the scientists engaged in this research are dedicated to helping patients with debilitating and deadly diseases. [1]: /lookup/doi/10.1126/science.1069614