ACCRUED MORAL STATUS
The major alternative to the view that an embryo has an inherent moral status is the assertion that moral status is an accrued or accumulated quality related to some physical dimension of form or function. Several arguments have been put forward for this position.
Gastrulation. One such accrual argument is based on the assumption that before gastrulation (which begins with the formation of the primitive streak around the fourteenth day), the embryo is an inchoate clump of cells with no actuated drive in the direction of distinct development. It is argued that the undifferentiated quality of the blastocyst (the 4–5 d embryo) justifies its disaggregation for the procurement of stem cells, while the evident organization at gastrulation reveals an organismal integrity that endows inviolable moral status to all subsequent stages of embryological development.
However, scientific evidence supports the opposing argument that from conception there is an unbroken continuity in the differentiation and organization of the emerging individual life. The antero-posterior axis appears to be already established within the zygote; the first cell divisions are asymmetric and early differences in gene expression suggest distinct cell fates, and an overall pattern of integrated unity seems to indicate a coherence of coordinated growth from the beginning.
All this implies that the changes at gastrulation do not represent a discontinuity of ontological significance (a change in the nature of being), but merely the visibly evident culmination of more subtle developmental processes at the cellular level that are driving in the direction of organismal maturity (5–7).
Twinning. Another argument for accrued moral status is that as long as an embryo is capable of giving rise to a twin it cannot be considered to have the moral standing of an individual. Yet monozygotic twinning, which occurs in just one in 240 births, does not appear to be either an intrinsic drive or a random process within embryogenesis. Rather, it results from a disruption of normal development by a mechanical or biochemical disturbance of fragile cell relationships. This provokes a compensatory repair, but with the restitution of integrity within two distinct trajectories of embryological development (8).
In considering the implications of twinning for individuation, one might better ask the question from the opposite perspective. What keeps each of the cells of the early embryo from becoming a full embryo? Clearly, crucial relational dynamics of position and intercellular communication are already at work establishing the unified pattern of the emerging individual (9). From this perspective, twinning is not evidence of the absence of an individual, but of an extraordinary power of compensatory repair that reflects more fully the potency of the individual drive to fullness of form even in the earliest stages of embryonic human life.
Implantation. Some have argued that the implantation of the embryo within the uterine lining of the mother constitutes a moment of altered moral status. Implantation, however, is actually a process that extends from around the sixth or seventh day to about the eleventh or twelfth day when the utero-placental circulation is established. The more complex circulatory exchange of the placenta simply extends the earlier relationship between mother and embryo in which diffusion of essential nutrients and growth factors sustain the life and nourish the growth of the developing embryo. Implantation, then, must be viewed as just another step in a continuum of ongoing intimate dependence, all occurring along the trajectory of natural development that begins with conception and continues into infancy. This continuity implies no meaningful moral marker at implantation.
Some argue in the case of IVF, however, that before implantation the embryo has no future prospects of development and therefore no natural potential on which to base moral valuation. They speak of the "un-enabled" character of these entities, and claim this deficiency of context justifies their use in scientific research. However, depriving an embryo of its environment does not change its intrinsic nature. To deny the moral standing of the pre-implantation embryo shifts the moral basis away from its intrinsic nature and places it entirely within the realm of external intention, subject to the whim of the research scientist.
Function. Most other arguments relate in some way to the onset of a specific function or capacity. The first and most obvious problem is that the essential functions (and even their minimal criteria and age of onset) are diverse and arbitrarily assigned. Generally they relate to the onset of sentience, awareness of pain, or some apparently unique human cognitive capability such as reflective self-consciousness.
This approach raises a number of disturbing ethical questions. If human moral worth is based on actual manifest functions, then does more of that function give an individual life a higher moral value? And what are we to make of the parallel functional capacities in animals that we routinely sacrifice for food and medical research? Furthermore, what becomes of human moral status with the degeneration or disappearance of such functions? While we might argue that our relational obligations change along with changes in function, such as occur with senile dementia, our society would not sanction a utilitarian calculus and the purely instrumental use of such persons no matter how promising the medical benefits might be.
More fundamentally, from a scientific perspective, there is no meaningful moment when one can definitively designate the biologic origins of a human characteristic such as consciousness. The human being is an inseparable psycho-physical unity. Our thinking is in and through our bodily being, and thus the roots of our consciousness reach deep into our development. The earliest stages of human development serve as the indispensable and enduring foundations for the powers of freedom and self-awareness that reach their fullest expression in the adult form.
From the perspective of this analysis, we can conclude that the embryo has a moral status that is inherent and not an accrued or accumulated quality, and that moral status must begin with the zygote (or clonote). Because it is intrinsic, such moral status, as distinguished from developing relational obligations, is therefore independent of: 1) the means by which the entity came into being (sexual intercourse, IVF, cloning or other); 2) the present location of the entity (in- or outside of a natural or artificial womb); and 3) the intention according to which such entity was produced (human reproduction, scientific and medical research, medical therapeutic use, or other).
Failures of fertilization. While inviolable moral standing is attributed to the human embryo, recent scientific evidence suggests that many, perhaps most, early natural initiations in reproduction result in failures of fertilization. If the zygote lacks essential elements such as the necessary complement of chromosomes, proper chromatin configuration and cytoplasmic factors for gene expression, it will also lack an inherent potency, a self-organizing drive in the direction of the mature form. It will not have the characteristics necessary for it to be an organism, and therefore will not be an embryo. Naturally occurring failures of fertilization may still proceed along partial trajectories of organic growth, however. For example, grossly abnormal karyotypes such as trisomies of chromosome number one (the largest chromosome, with the most genes) will form a blastocyst but will not implant (10). Even an egg without a nucleus, when artificially activated has the developmental power to proceed through several cell divisions, yet clearly is not an embryo, or an organism at all. Like a spinning top, the cells contain a certain biologic momentum that propels a partial trajectory of development, but unlike a normal embryo they are unable to bootstrap themselves into becoming an integrated and self-regulating organism.
Some of these aberrant products of fertilization that lack the qualities and characteristics of an organism, appear to be capable of generating ESCs or their functional equivalent (11). Mature teratomas are tumors (generally benign) that generate all three primary embryonic cell types as well as more advanced cells and tissues, including partial limb and organ primordia—and sometimes hair, fingernails and even fully formed teeth. Yet these chaotic, disorganized, and non-functional masses are like a bag of jumbled puzzle parts, lacking entirely the structural and dynamic character of organisms. Neither medical science nor the major religious traditions have ever considered these growths to be moral beings worthy of protection, even though they appear to produce ESCs.