The question of when human life begins is critical in debates related to life issues. While there are a variety of proposals as to how an organism should be defined, many biologists and ethicists, particularly Catholics, have approached this issue by arguing that fertilization defines the beginning of a new organism. Examining the processes of fission and fusion, which take place before gastrulation, provides strong evidence for when human life beings and therefore how it should be defined. Among the four (...) dominant theories, regulative fission and fusion are the best explanations in terms of being the most consistent with the biological data. This explanation of twinning provides compelling evidence that fertilization is not a necessary condition for human generation, although it may be a sufficient condition. While fertilization generates the vast majority of human beings, additional human beings may rarely be generated during fission events. (shrink)

This essay has two purposes. The first is to argue that our moral duties towards human embryos should be assessed in light of the Golden Rule by asking the normative question, “how would I want to be treated if I were an embryo?” Some reject the proposition “I was an embryo” on the basis that embryos should not be recognized as persons. This essay replies to five common arguments denying the personhood of human embryos: (1) that early human embryos lack (...) ontological individuation; (2) that they are members of the species Homo sapiens but not yet human persons; (3) that the argument for personhood commits the “heap argument” fallacy; (4) that since human procreation in nature is inefficient, human embryos cannot be persons; and (5) the “burning building” scenario proves that all arguments for personhood are irrational or inconsistent. The second purpose is to set forth and criticize in light of the normative judgement defended in part one the present legal situation of cryo-preserved embryos in the U.S. The essay ends by proposing legislative reforms to protect ex utero human embryos. (shrink)