As noted above, the newly formed single-cell embryonic human zygote consists of 46 chromosomes and non-nuclear DNA in which are coded the specific directions for virtually all of the processes of embryological development. The content of this initial pool of genetic information never changes throughout embryological development.
(1) Yet it has been argued by Bedate, Cefalo47 and Bole48 , for example (Fig. 1), that not all of the "information" needed is present in this single original cell, that some of the information comes from "molecular information" in later stages of development, and some even comes from "molecules" originating from the mother. Thus they conclude that the original human zygote does not contain all of the "information" needed to be a self-directing, human individual, and therefore it is not a human person.
I would question this biological data. First, "molecular information" or "positional information" is not the same as genetic (chromosomal) information. Yet they seem to gloss over this very important scientific distinction, and imply that the two are the same. Second, "molecular information" itself is coded in the original single-cell human zygote. As the embryologist Moore discusses at great length, the genetic information in the original human zygote determines what "molecular information" will be formed, which in turn determine what proteins and enzymes will be formed, which determine which tissues and organs will be formed. In genetics this is called the "cascading" effect.49 That is, the information in the original single-cell embryonic human zygote "cascades" throughout embryological development - each previous direction causing the specific formation of each succeeding direction. Thus, all "positional" or "molecular" information or direction is already determined itself by the information which preceded it, and ultimately by the original genetic information in the single-cell human zygote.50
Third, although the genetic information in the human zygote may direct the absorption of molecules from the mother, that hardly means that the maternal molecules or the mother herself determines the very nature of the growing embryo or fetus which she is merely nurturing. (This argument is also rejected by Suarez51 ). The nature of the embryo or fetus, as is empirically known, is determined by the formal biological genetic make-up of the zygote from which he or she continuously develops; and the directing of this absorption of maternal molecules is done by the genetic information within the embryo or fetus - not by the mother or any genetic or "molecular" information from the mother.52 Those are simply the correct biological facts. As Jerome Lejeune, the internationally prominent prize winning geneticist has testified:
…each of us has a unique beginning, the moment of conception… As soon as the twenty three chromosomes carried by the sperm encounter the twenty-three chromosomes carried by the ovum, the whole information necessary and sufficient to spell out all the characteristics of the new being is gathered… (W)hen this information carried by the sperm and by the ovum has encountered each other, then a new human being is defined which has never occurred before and will never occur again…. [the zygote,and the cells produced in the succeeding divisions] is not just simply a non-descript cell, or a "population" or loose "collection" of cells, but a very specialized individual, i.e., someone who will build himself according to his own rule."53 (emphasis added)
Finally, Bedate and Cefalo54 also argue that the developing embryo can give rise to biological entities which are not human beings, e.g., hydatidiform moles and teratomas. But hydatidiform moles and teratomas do not arise from genetically normal human embryos, but from abnormal entities (usually caused, e.g., by dispermy), which are not therefore genetically normal human beings to begin with.55
(2) Next, it is argued by some that this original single cell divides neatly first into 2 cells, then into 4 cells, then into 8 cells, etc.56 This biological data too is questionable, (and has consequences in understanding the argument about "totipotency"). As known and published in human embryology textbooks for over 60 years (as Lejeune57 points out), human embryogenesis immediately following fertilization is asynchronus (unlike amphibian or mouse embryology). The original single cell divides into 2 cells - and then only one of those cells divides, giving 3 cells . After a time the other cell divides, making it 4 cells, and then 8 cells, etc.
Part of what happens at this three-cell stage is that one can observe empirically the process of methylation. This observation is important philosophically. Many argue that these very early cells - including the original single-cell zygote up to the 8-cell stage - are "totipotent".58 They explain totipotent cells as the most vaguely directed and least differentiated cells in all of embryological development. Each cell, they claim, is not yet determined enough to be classified as an individual human being or a part of an individual human being. These cells, they say, have not yet "made up their minds" what they want to be. They can become any number of things. These cells are not differentiated or specialized enough yet. What happens in early development, they claim, is that there is a gradual change from total unspecialization to greater and greater specialization or differentiation. For example, at first we have a cell that could become any kind of human cell. Progressively a cell becomes specialized so that it can only become a kidney cell, or a stomach cell, or a muscle cell, i.e., it becomes more and more determined and differentiated.
This portrayal of differentiation is backwards, as Lejeune notes. The original single-cell human zygote is the most determined and specialized cell in all of embryological development. Progressively he or she loses, in fact, the ability to use information. A kidney cell, for example, contains virtually all of the genetic information that was in the original single human zygote cell, but can now use only a small portion of that information. So the kidney cell has not lost any of this information - only the ability to use it. This ability to use or not use the information that is present is partially determined by the process of methylation (which itself is coded in the original single-cell zygote). Through methylation and other processes during embryogenesis, genes are turned on or turned off. When the cell wants to control the use of cellular information, it methylates a molecule to silence that gene, to block or stop its use at a certain point in development. No information is progressively lost; only its use is lost. Thus a specialized kidney cell cannot be prodded to become an entirely new human being - not because it does not have all of the necessary information (it does), but because all of the information other than that of being a "kidney cell" has been methylated, or silenced.59
Thus to be so differentiated as a kidney cell is actually a negative in such arguments. The kidney cell cannot direct anything but a small minuscule part of the development of the human embryo or fetus; whereas the original single-cell human zygote contains and can use all of the genetic information only partially used by the later cells. So there is nothing vague, undirected or undecided about it. It is the human zygote which represents the greatest fullness of human content and useable information, of directedness and decisive action - more than that found in any of the later cells. The human zygote will "decide" what reactions and formations take place. He or she will direct all of the processes and formations during the entire embryological process.60 Furthermore, "totipotency" is even suppose to happen - it is a normal part of human embryogenesis, and is indeed encoded in the original genetic information of the human zygote. Differentiation is also encoded in the original human zygote, and is partly explained by methylation. Differentiation, then, really represents the restricted ability to make any "decisions".
(3) Next, Suarez argues for the 2-cell stage, with, as he claims, the completion of the first division and of the genetic input. "The two-cell stage already is, like the adult, a moment in the execution of the program 'man'". And besides, he argues, the two-cell stage is already the same living being as the human adult arising from it.61 However, we already know that the genetic input is complete at the single-cell zygote stage, and that the zygote in fact is the source of the genetic input of the two-cell stage and is the same living being as both the two-cell stage and the adult stage. Thus Suarez's own argument actually argues for personhood for the zygote rather than for his two-cell stage.
(4) But to continue, the cells will proceed to divide until about 5 or 6 days, when two cell layers are formed in the blastocyst - the trophoblast or outer cell layer, and the embryoblast or inner cell layer. Some writers, such as Grobstein and McCormick, have stated that this stage is significant because they can demonstrate empirically that there can be no true human individual present at this time - we have only a genetic individual, not a developmental individual. A person can be present, they claim, only if there is a developmental individual -and this cannot take place until 14-days:
I contend in this paper that the moral status - and specifically the controversial issue of personhood is related to the attainment of developmental individuality (being the source of one individual)… It should be noted that at the zygote stage the genetic individual is not yet developmentally single - a source of only one individual. As we will see, that does not occur until a single body axis has begun to form, near the end of the second week post fertilization when implantation is underway.62 (emphasis added)
It is to be noted that the moral status of the developing human being explicitly hinges directly on what developmental stage he or she is at. Note also that they make implantation (5-7 days) co-extensive with two weeks (when the primitive streak begins to form) - also scientifically incorrect.
But to continue, these early cells, they claim, are only "collections" of undifferentiated, "totipotent" cells, and they name them, or designate them collectively, as only comprising a "pre-embryo" (a term, by the way, which is specifically rejected by human embryologists63 - only amphibian and mouse embryologists, philosophers, theologians and bioethicists use the term). Further, the term was rejected by the judge in the Davis vs Davis frozen embryo case.
The scientific facts which they give to support these claims are the following. They claim that only the cells from the inner layer of the blastocyst (the embryoblast), eventually become the adult human being. The cells from the outer trophoblast layer, they write, are all discarded after birth as the sac and the umbilical cord, etc. Thus, developmentally, the implication is, that we are not dealing exclusively with those "important cells" which will become the adult human being, i.e., the embryoblast, but rather a mixture of "essential" and "non-essential" cells, i.e., a PRE-embryo. A pre-embryo, then, is not a human person, yet:
This multicellular entity, called a blastocyst, has an outer cellular wall, a central fluid-filled cavity and a small gathering of cells at one end known as the inner cell mass. Developmental studies show that the cells of the outer wall become the trophoblast (feeding layer) and are precursors to the later placenta. Ultimately, all these cells are discarded at birth64 (emphasis added)
But, again, these scientific "facts" are questionable, and necessarily lead to questionable philosophical concepts. It simply is not true that all of the cells from the trophoblast layer are discarded after birth and do not contribute cells to the inner cell layer; nor is it true that only the cells from the inner layer become the later adult or that none of the cells from the inner cell layer contribute to the outer layer. As can be found in virtually all embryology texts, including Moore's text from which they quote, many of the cells from this trophoblast layer become an integral and essential part of the constitution of the later fetus, newborn and adult human being. For example, the cells from the trophoblast layer known as the yolk sac cells become part of the adult gut. And cells known as the allantois cells become part of the adult ligaments, blood cells and urinary bladder.65
Thus these "scientific" facts used by Grobstein and McCormick are scientifically incorrect - and therefore so also are their philosophical conclusions about "pre-embryos" and "developmental individuals" which are grounded on those incorrect scientific facts.
Yet McCormick and Grobstein continue. It is impossible, they claim, for a human person to be present until at least the 14-day marker event, at which point the primitive streak forms in the embryo. The philosophical significance of this marker, it is claimed, is that until the formation of the primitive streak it is possible for twinning to take place. The totipotent cells "do not yet know whether to be one or two individuals". After 14-days, they claim, twinning is not possible, and thus the organism is finally determinantly developmentally one individual - an essential pre-requisite for personhood.66
But, again, this science is incorrect. As Karen Dawson67 points out in these debates - and as is found in every human genetics textbook - it is possible for monozygotic twinning to take place after 14-days and the formation of the primitive streak. For example, fetus-in-fetu twins can be formed up to 2 and 3 months after fertilization, and Siamese twins even later. Also, it is known that "twinning" is sometimes genetically determined and coded in the original human single-cell zygote (as, indeed, is totipotency and differentiation).
There is nothing magical, it turns out, about this 14-day stage as far as the concept of individuality and personhood is concerned. (Even the Warnock Report, which encouraged the use of the term "pre-embryo", admitted that the 14-day marker event or any other was totally arbitrary, as did the NIH Human Embryo Research Panel).68 If a 2-cell, 8-cell, implantation stage, 14-day primitive streak stage embryo or 4 month fetus splits into twins, that simply means that the original entity was one individual - and now there are simply two individuals. The fact of twinning says nothing about the individuality of the first individual, i.e., the single-cell human zygote.69 Indeed, the history of all living organisms is of one individual giving rise to another individual - but one would certainly not then conclude that there were therefore no individuals ever present, or that the former individual was hopelessly "undecided".
C. Ward Kischer, a human embryologist, argues that the scientific data of McCormick and Grobstein is highly selective and that they leave out a majority of other relevant data:
It is not a question as to whether science can or cannot decide the question of personhood. Science is not interested in deciding personhood. However, if the socio-legal status of personhood cannot be decided without invoking what is known scientifically, then the whole of scientific data should be used and not arbitrarily selected bits and pieces of data. (emphasis in original)
… Human embryology is now in danger of being rewritten as a stratagem statement of current socio-legal, but also of late, even theological issues. Unless the errors are corrected now, we will be in danger of entering a protracted period of false concepts concerning our own development.70
Unfortunately, Grobstein later publicly admitted before a scientific conference that he had knowingly substituted amphibian embryology for human embryology.71 Yet this "science" continues to be promoted. For example, there are the claims by Robertson (a lawyer) that "personhood" is only a social construct and that the early human embryo has only "symbolic value" to the parents and society.72 But Robertson bases his argument almost exclusively and exhaustively on the "embryology" of Grobstein, even in his court cases. And recently, the N.I.H. Human Embryo Research Panel issued its Recommendations to the Director of N.I.H. Ron Greene and Carol Tauer, the Ethics Co-Chairpersons of that Panel, grounded the "reduced moral status" of the early human embryo on the published work of Grobstein and McCormick, and most of the writers considered here73 - concluding that certain kinds of destructive experimental research could ethically be performed on these early live human embryos because of their "reduced moral status". Furthermore, certain pharmaceutical companies have argued that the F.D.A. should allow them to market oral contraceptives because there is "no embryo there until two weeks", and therefore their product is not abortifacient. Their source for this scientific claim is the Australian theologian Fr. Norman Ford's book (below), grounded on the "science" of Grobstein and McCormick.74 Obviously, if Grobstein's embryology is incorrect, then Robertson's argument, the N.I.H.'s Recommendations, and the claims by the pharmaceutical industry and advocates which are all based on Grobstein's "embryology" are also invalid.
(5) Ford75 also argues for the 14-day stage, based primarily on the same science from Grobstein, although Ford claims there is an individual present at fertilization - but it is only a biological individual. Rational ensoulment cannot take place until after 14 days, at which point there is, he claims, an ontological individual, i.e., when differentiation is completed and there is a distinct individuality.76 But aside from the problems with the science of Grobstein and McCormick on which Ford basis his own conclusions, we know empirically that complete differentiation does not actually take place until well after birth. As the embryologist Moore states:
Human development is a continuous process that begins when an ovum from a female is fertilized by a sperm from a male. Growth and differentiation transform the zygote, a single cell formed by the union of the ovum and the sperm, into a multicellular adult human being. Most developmental changes occur during the embryonic and the fetal periods, but important changes also occur during the other periods of development: childhood, adolescence, and adulthood… Although it is customary to divide development into prenatal and postnatal periods, it is important to realize that birth is merely a dramatic event during development resulting in a distinct change in environment. Development does not stop at birth: important developmental changes, in addition to growth, occur after birth… Most developmental changes are completed by the age of 25.77 (emphasis added)
Obviously, then, a 14-day embryo is nowhere near being "completely differentiated". Once again, the incorrect science on which a philosophical claim is based actually negates the validity of that philosophical claim.
(1) Sometimes Wallace,78 too, wants to argue for 14-days, but he is inconsistent and seems more to argue for a point after 14-days. He bases his own position on what he calls an "Aristotelean-Thomistic" theory of "natural law". This "natural law theory" grounds his distinction between transient natures (or seeds, or beings-on-the-way) as applied dubiously and analogously to the transition from plant, animal, to human natures during human embryological development; and stable natures, as applied to the actual embryological development of individual systems of plants, animals and human beings. This "transition" from plant, animal to human substances during human embryological development for Wallace is, then, actually a series of substantial changes within human embryogenesis itself; and once again he bases much of his argument on the science of Grobstein and McCormick, and a rather neo-Platonic rendition of Aristotle and Aquinas, as well as a distinctively physicist's rendition of "science".
Two points out of many which are problematic are his descriptions of his "Aristotelean-Thomistic" grounding, and the blatant contradictions in his analogies. First, Wallace subscribes to the Aristotle of the historically problematic De Anima, and attributes to both Aristotle and Thomas a theory of the "eduction" of these substantial forms from "proto-matter", substantial forms which Aristotle, he says, would call "natures", and which Thomas, he says, would define as (quantity + proto-matter) - a definition of substance with which neither Aristotle-proper nor Thomas would agree. Wallace renames this as "mass-energy", to bring Aristotle and Thomas "up to date with modern physics".79
However, Wallace is really elucidating a very neo-Platonic interpretation of both Aristotle and Thomas, one with which neither the historic Aristotle nor Thomas can be reconciled. Neither of them gave any real existence to "proto-matter", or what I think Wallace confuses with "prime matter". And, indeed, for both of them "prime matter" was only a conceptual construct, and by definition, was totally without forms80 - in fact, that was the whole point! As Klubertanz states:
Of itself, prime matter is not actually any kind of thing; nor does it have quantity, or any kind of qualities or other accidents. Hence prime matter cannot exist in itself; it cannot be found as such in direct or indirect sense experience; it cannot even be understood separately from substance or substantial form. It is an intelligible co-principle…81 (emphasis added)
Thus no substantial forms can be educed from "proto-matter" for either Aristotle or Thomas, because there were no forms there to begin with. And Thomas, like Aristotle, actually argued against this sort of theory:
Creation does not mean the building up of a composite thing from pre-existing principles; but it means that the composite is created so that it is brought into being at the same time with all its principles.82 (emphasis added)
Further, "quantity" for both Aristotle and Thomas was an accident of substance, not a concrete substance itself.83 Thus neither would even equate their "quantity" with the modern concept of "mass". And finally, Wallace also never once includes esse (the act of existing) - which is the hallmark of Thomas' definition of any existing substance - in any of the definitions of "substance" which he attributes to Thomas. In fact, he simply never mentions esse at all.
Second, his concept of "transient natures" is drawn from rather shaky chemistry and biology. He claims, for example, that when Na and Cl react together they each actually change their natures. But Na and Cl are only sharing electrons, not protons (which determine the "nature" or kind of element it is, and which place the element in a specific place in the periodic chart). He also fails to mark the critical differences between the nuclei of radio-isotopes and those of living cells. Nor does he mark the critical differences which distinguish the generation of a radioisotope from that of a plant; nor that of an animal from that of a human being. He also builds a "model" of what he calls "transient natures", yet admits that they probably are really "stable natures"! Inexplicably he will call them "transient natures" anyway.84 He then applies his own theory of transient natures, questionable even to himself -to plant and animal generation - all the while acknowledging that real plants and real animals have stable natures which are descriptive of the mature individuals only - not to the developmental stages of those individuals.85 How credible is such a theory? Should it be applied to determine the real moral status of real live human beings?
(2) A final marker event I will point out is 8 weeks or several time-markers after that (Fig. 2) - although there are many others with equally troubling science invoked. Personhood, it is claimed, does not begin until the dawning of or the maturation of the physical substrate of human consciousness, self-consciousness, or sentience - i.e., the nervous system and/or the brain. Indeed, there is already a movement by some in legal jurisprudence to formalize the legal concept of "brain birth" to denote that point in time biologically when there is present a "person", as a parallel to the already legal criteria of "brain death".
One well-known criticism of this claim comes from Gareth Jones, who rejects scientific claims that we can determine the biological point of either "rational attributes" or sentience. As he states, the parallelism between brain death and brain birth is scientifically invalid. Brain death is the gradual or rapid cessation of the functions of a brain. Brain birth is the very gradual acquisition of the functions of a developing neural system. This developing neural system is not a brain. He questions, in fact, the entire assumption and asks what neurological reasons there might be for concluding that an incapacity for consciousness becomes a capacity for consciousness once this point is passed. Jones continues that the alleged symmetry is not as strong as is sometimes assumed, and that it has yet to be provided with a firm biological base.86 A different Jones who is partaking in these debates makes the following poignant remark:
The reproductive biologist cannot assign moral status to the sperm or the egg or the fertilized egg or any of the subsequent products that may result from this fusion … The reproductive biologist can help, however, by assuring that other scientists or those who wish to assert a moral status, and use a biological term or concept to do so, know what they are talking about!87 (emphasis added)
Furthermore, the empirical fact is that complete physiological brain integration is not complete until many months or years after birth,88 just as the complete exercising of "rational attributes" is not possible until years after birth.89 Empirically this would extend their biological marker for personhood into early adulthood (and thus the moral status as well).