The biological individuality of the human embryo
Gonzalo Herranz, department of Bioethics, University of Navarra
discussion paper at the I International Symposium on Bioethics in Homage to Jerôme Lejeune.
Austral University. Buenos Aires, October 26, 1995, 09:30.
A little common sense before getting started
The devaluation of fertilization
Individuation, a decisive topic
Does the biological soil withstand the weight of ethical construction?
Greetings
One of the most attractive and at the same time most difficult challenges of Bioethics and in the case of medical ethics is that of trying to define and justify the ethical significance of data and of biological phenomena. Bioethics is not only concerned with reflecting on how ethical principles apply to the new opportunities that modern biology offers us with its discoveries and inventions. Bioethics must also ask itself to what extent the findings of biomedical research make us know the natural world and mankind better and, consequently, enlighten us on how best to relate to the realm of the living and the human family.
Jerôme Lejeune was an acute search engine of the ethical significance of the biological data . He always tried to discover the harmony with which the creative action of God simultaneously adorned the structure of living beings and our moral responsibility. And he never ceased in his honest and brilliant effort to understand and agree the law that governs natural phenomena and that which, engraved in our hearts, must govern our conduct.
I feel his absence today in a special way. He lovingly defended, with solid scientific data and attractive parables, the fully human biological identity of the embryo. I lack his sharp wit, his persuasive, almost seductive words. I hope that from heaven he will have mercy on you and make my intervention this morning tolerable.
The topic I have been invited to talk about is not a simple one. Judging by what is published about it, we are sample lodged in a confusing field, in a gray zone, where one discussion and one disagrees. But this is a new discussion , a disagreement provoked by the opportunities opened up by scientific progress to manipulate nature and man.
Until about twenty years ago, any book on human embryology began more or less like this: The development of a human individual begins with fertilization, a phenomenon by virtue of which two highly specialized cells, the spermatozoon of the male and the oocyte of the female, unite and give rise to a new organism, the zygote. Ontogenesis was regarded as a process that began with fertilization and developed in a continuous way, which embryologists described in minute detail in terms of form and time. Until then, everyone had researched and taught the simple view that ontogenesis was linear, rectilinear: the initial human embryo was result of the procreative action of a man and a woman, which grew and differentiated continuously, without qualitative leaps, as fully human at the beginning as at the end of its intrauterine life.
I think that almost all of us, in our heart of hearts, still think this way. The Danish Ethics committee , the most democratic of all the National Bioethics Committees, which promotes wide consultation among the public, which does not publish its guidelines until after many open debates through the press, radio and television; which, in 1988, very democratically regretted that in vitro fertilization had been introduced in Denmark without the public having had the opportunity to debate the advantages and disadvantages of this method, pointed out in its 1990 report that "in man, the development from fertilized egg to embryo to fetus is a continuous process. The committee does not find that a certain point in its time course can be singled out at which the Degree of respect for which it deserves to be protected changes decisively".
However, things became complicated and, in a way, obscure twenty years ago now, when two new, curiously antithetical achievements of biomedical control of the transmission of human life began to develop and become socially accepted almost at the same time: one was the production of test-tube children through assisted reproduction, especially in vitro fertilization; the other, contraception triggered by an antinidatory effect, as with IUDs, certain hormonal combinations, or contragestational contraceptives.
Both advances had a common feature of important ethical implications: they involved the loss or destruction of very young human embryos.
As it is easy to understand, the problem was raised then in very acute and urgent terms, which lasts until today, about the ethical rank and legal status of the young human embryo, viz: whether we should maintain, and for what reasons, the classical and unlimited respect for human life, including that of those young embryos, as, for example, prescribed in the fifth commandment of the Decalogue or in the Geneva Declaration of the World Medical association (I will show the utmost respect for life from the moment of conception), because young human embryos are human beings who claim from us an ethical respect plenary session of the Executive Council . Or if, on the contrary, as it is convenient to the new way of seeing things, zygotes, in vitro cultivated embryos and pre-implanted embryos, or those of an age lower than an established deadline , would be pre-human entities that should be placed in a lower ethical stratum, since they would lack the dignity and rights proper to man. The answer to this problem has far-reaching theoretical and practical consequences.
A little common sense before getting started
Throughout the last two decades, the battle between those who defend one camp and the other has been fierce. The confrontation seems to be reactivated when the media report on new legislation that is being prepared or on increasingly strange and surprising clinical cases. The problem also jumps from time to time to the opinion pages of scientific publications.
In order to show what subject arguments are used in the world of science to activate ideological change, erode classical concepts and promote the establishment of new ideas, it seems appropriate to bring up here the most salient features of a recent controversy.
Last January, a Scottish ecologist, John Godfrey, wrote a Commentary in Nature magazine on some ideas that Pope John Paul II expounds in the book Crossing the Threshold of Hope. Godfrey wonders how it is possible for the Pope to ignore modern biological science and the teachings of Thomas Aquinas when dealing with the problems posed by human reproduction: (I quote Godfrey) The biological and ethical problem he [the Pope] raises is the origin of the individual person during prenatal life. But there is no point at which human life begins. It is clear that both the egg and the sperm are alive, and that their life is human, and that life is continuous from one generation to the next. And yet life at that [prenatal] stage is not yet that of a person. [The Pope accepts the misconception that there is a moment when fertilization takes place. The process of fertilization is complex and lasts about two days. [...] During this period [of fertilization], the identity has yet to be established Genetics. During activation, there is a rapid and irreversible change, which, although rapid, is not instantaneous. [...] What is serious is that activation, being essential for the subsequent development , precedes the chromosomal phenomena that establish the identity Genetics of the zygote. Therefore, a new individual cannot have its origin in activation. During the first four days, all genetically determined properties of the fertilized egg are maternal. Only after these days do the paternal genes begin to act, and only then is there a gene expression that characterizes the new individual. But even then, stable individuality is still a long way off. [...] A couple of weeks after fertilization, a single embryo can still divide and produce identical twins. And only then do the parts that make up the individual develop.
So much for Godfrey's long quotation . I cannot now undertake the task of refuting Godfrey's ideas one by one, for I will pay attention to some of them later. What I want to point out here is the scientistic naiveté of Godfrey who, as it were, waves with a conviction, very sincere and full of superiority, before the Pope's face some scientific data as if they constituted the only existing reality in the world capable of offering criteria of moral judgment. (I cannot but point out, however, in punishment of Godfrey, one fact, to show how anti-scientific is the attitude of the scientism: they do not believe in scientific progress. During the first four days, all the genetically determined properties of the fertilized egg are maternal, says Godfrey. Not even three months after the publication of his Commentary, the same journal Nature published the fact that the gene for masculinity, located on the Y chromosome of male embryos, is already expressed at the two-blastomere stage, on the second day after fertilization). I continue:
Not surprisingly, the above ideas and others in Godfrey's Commentary prompted many to write to publisher of Nature. Over the following weeks, the journal published no small issue of letters, including one from me, that set out to dismantle many of Godfrey's inferences.
In that letter, I drew attention to two points: to the lack of scientific legitimacy of Godfrey's basic thesis "there is no moment when human life begins"; and to the danger of turning the data of scientific observation into the exclusive meter patron saint of human morality, i.e., that it is ethics that, by system, submits to the convenience of scientists, and not scientists who guide their work by respect for the moral law.
I said in my letter on the first point: "The axiom 'There is no moment when human life begins' should be discarded as unfounded. If it means that life is transmitted from one generation to the next, then it is a dull platitude, for the theories of spontaneous generation have long since been disproved. If it is used to disseminate the idea that (human) life consists of a diffuse living magma from which emerge individuals of indeterminate and obscure origin, then it is mere obscurantism. [...] From the fact that the ovum and sperm are alive Godfrey concludes that no definite beginning can be assigned to individual human life. Such a conclusion is an illegitimate inference. Good sense compels us to recognize that oocyte and sperm are radically different from zygote. Gametes are wonderfully differentiated but terminal cells, irrevocably doomed to die within a few hours or days. Fertilization changes things in a spectacular, radical way: apart from being a complex cellular phenomenon, fertilization is capable of originating a new, sudden and violent explosion of life that grows and lasts for years and years".
On the second point he noted: "When the Pope speaks of fertilization, he is not analyzing cellular and molecular phenomena in a reductionist way, but is referring to the human act of begetting children. Godfrey's blurred image of fertilization denies a basic, inexcusable fact of life: parenthood. If human life does not begin with fertilization, what then is to be made of the decisive biological and human role of the father in the generation of the child? According to Godfrey, children seem to emerge as products of an anonymous and asexual continuum, and not of the love and flesh of a woman and a man".
Naturally, the controversy was not resolved. Among other things, because Godfrey chose not to reply to the letters published in the magazine. But I would like to draw a conclusion from the above: we must hold science in the highest esteem, we cannot ignore the new facts it discovers or the new and challenging explanations it offers us. But neither can we ever cut our ties with the real world, with common sense. Scientists and their way of seeing life and the world run the risk of being locked in an ivory tower disconnected from the most basic human realities. Much of what has been said about assisted reproduction in the scientific, legal and philosophical fields is wounded by this lack of connection with human realities. That is why it was justified, in my opinion, to begin our study of the problem by appealing to moral common sense, and to judge things with the simplicity of that supreme figure of ethics who is the common man who has not lost, but has taken care of his common moral sense.
The devaluation of fertilization
In vitro fertilizers are interested in affirming that the zygote is something irrelevant, a molecular product devoid of human form and value; that the young embryo is a report mass of embryonic material, of indeterminate, totipotent cells. Only by depriving the embryos that they produce, handle and destroy of their human character, could one ethically neutralize the considerable loss of embryos that the internship reproduction of laboratory entails.
They use two platforms to launch their message: from one they proclaim the triviality of fertilization as a biological phenomenon; from the other, they deprive the embryo of individuality, and therefore of human rights, during its first two weeks of life. Let us attend, for a moment, to the argument that trivializes fertilization.
They tenaciously insist that fertilization is a relatively banal moment, without the significance and transcendence that others attribute to it. Robert G. Edwards speaks in defense of this point of view at purpose of the research on human embryos:
Such a research raises fundamental questions about the human embryo, issues such as when life begins, or whether embryos have any rights. The embryos we are talking about are tiny: thousands of them could fit in the volume of a drop. They are tiny clumps of cells; they have no hands, feet, or head. They assume changing forms, but under none of them have the slightest resemblance to a human being until seven weeks of gestation have passed. And yet there is a crying ethical question surrounding these tiny specks of life, in which the opportunities for doing good conflict with the value attached to incipient life.
What Edwards has said up to this point deserves a comment. After having worked for many years with human embryos whose fate he has owned, Edwards has ended up considering them as mere molecular complexes, as tiny cellular aggregates, and he judges them by their mere appearance, not by what they are in themselves. Edwards is a victim of mechanistic Darwinism, a blindness described by Cambridge philosopher David Holbrook.
Some people," Edwards continues, " object to research on human embryos because they believe that life begins at fertilization. Those who think this way are in fundamental error, because they oppose the programs of study on in vitro fertilization and its applications. They use the absolutist argument that, with fertilization, the embryo receives all human rights. They say that the embryo is worth the same as a child or an adult, and that destroying embryos at research is the same as killing men.
The convenience of doing research -research destructive, in fact - becomes the rule unappealable of morality. The civil service examination to in vitro fertilization comes from hard hearts, who are opposed to curing the sterility of couples; and from hard heads who wish to paralyze the progress of science: in any case, a manifestation of fundamentalism. Moreover, to attribute human rights to the embryo, to include it in the family of man, is an intolerant absolutism. Now comes the trivialization of fertilization: these are the same ideas of Godfrey.
I," Edwards continues, " cannot share this opinion. Biological facts lead to contrary moral conclusions. Life is a continuum: it does not begin at any given moment. As alive as the embryo are the sperm and the oocyte that gave rise to it. The originality and unrepeatability Genetics of the sperm and the oocyte is no less than that of the new embryo; after all, the latter has received them from its precursor cells, which are cells lacking special ethical requirements. There are no points of reference letter between which a line can be drawn between life and non-life. There are too many arguments and exceptions to accept that fertilization is the beginning of life. Edwards then refers to how many children with Down syndrome are a mixture, a mosaic, of normal and other trisomic cells, whose mutual proportion is constantly changing; to how a fertilization can give rise to a hydatidiform mole, which is not a human being at all, but a tumorous training ; to how the parthenogenetic development , without fertilization, in some animal species reaches a very advanced Degree of development . And returning to more beaten paths, he wonders how fertilization can be the beginning of life if we know that some embryos can fuse and form genetic chimeras or that an embryo can split days after fertilization to give rise to two or more identical twins; or that a high proportion of the products of fertilization are so many other resounding biological failures condemned to die.
This is not the occasion to refute or evaluate so many claims, many of them captious, on their scientific merits and ethical significance. Being in small Degree a genetic mosaic is almost an ordinary way of life. Fertilization, like any biological process, is susceptible to strange pathological disorders: and hydatidiform mole is one of them. It is not easy to understand how parthenogenesis can be an argument against the value of fertilization, since it is radically inoperative in mammals. The loss of young embryos in reproductive processes, besides being one more manifestation of the reproductive precariousness that man shares with all living beings, is the heavy tribute that is demanded of us in exchange for the immense treasure of individual diversity.
Fertilization," Edwards concludes, " is merely one more stage, one stage in a long, complex and continuous process, so that choosing it as the beginning of life is as arbitrary as choosing any other. Fertilization is only one step in the development of a person. The zygote gradually develops into an embryo, and any line to mark when the embryo's rights begin is arbitrary. For my part, I would suggest that the period from 12 to 30 days after fertilization is a time that deserves to be taken into account and studied, as this is when nerve tissue begins to form.
The conclusion is surprising: the terrible condemnation of fundamentalist absolutism that the conceptionist view of human rights receives a couple of paragraphs above, now vanishes in a cloud of agnostic tolerance, from which the conceptionist view of classical Embryology and its thesis that one is human from the very first moment is exclusively excluded.
Individuation, a decisive topic
It is not easy for people without prejudices to accept the trivialization of fertilization as an argument to deny dignity to the young embryo. This explains why the center of gravity has shifted towards the developmentalist view. Two factors contributed decisively to this: the report presented by committee Warnock and the circulation of the term pre-embryo.
Let's dispatch in a few words the criticism of the syntagma pre-embryo. It is a word that has contributed in a very important way to consolidate the idea that our very beginning is an unreal, indefinite time. It tends to hide the fact that parents beget their children as indeterminate entities.
The term was not introduced to satisfy a scientific need or to designate a biological reality. On the contrary, many embryologists have spoken out against the use of the neologism, for being unnecessary for embryological taxonomy, and for being too loaded with moral prejudices and extra-scientific meanings. And it is true: the word pre-embryo was not created by an embryologist, but by Dr. Penelope Leach, a well-known psychologist. Therefore, it has not served to shed more light on the problems of descriptive, causal or molecular embryology, but to change the way of judging and acting of some in the political, legal or professional field. The journal Lancet stated, in a article publishing house , that it is very convenient to use the term pre-embryo, less emotionally charged than embryo, to designate the product of conception in its first 14 days [...] as it has done more than anything else to lower the temperature of the discussions around the research on embryos.
For many embryologists, the word pre-embryo is simply a semantic trick. I cannot expand any further on topic. Let's go back to committee Warnock and his proposal to set the age of 14 days for human embryos to be respected. It is a very interesting story. Baroness Mary Warnock tells that the committee she chaired went through a very serious crisis when it addressed the topic of experimentation on human embryos in vitro. The committee was divided into two opposing groups: those who defended that no limits should be placed on experimentation and those who demanded the absolute prohibition of destructive experimentation on these embryos. The Baroness came to fear that it would not be possible to break the deadlock, because the positions became more and more entrenched in their arguments.
The report Warnock relates the crisis with even-handed coolness: Some people argue that, if an embryo is human and alive, it follows that it should not be deprived of the opportunity to develop and, therefore, should not be used for the purposes of research. They would be willing to give moral approval to in vitro fertilization if, and only if, each embryo produced were transferred to a uterus. Others, while in no way denying that human embryos live (and must also concede that oocytes and sperm live as well), maintain that embryos are not yet human persons and that if it were possible to decide when an embryo becomes a person, it could be decided when, and when not, it would be permissible to perform research on them.
Baroness Warnock, faced with the impossibility of reaching a rational consensus, proposed an arbitration decision: that experimentation be accepted, limiting it to the first two weeks of life of in vitro embryos. With astonishment and satisfaction - he told the press - he saw that his proposal was accepted by the sides in dispute, so that the committee could continue its deliberations. In this simple way, a decision of enormous consequences entered the world of bioethics and law: the human family was split into two groups of beings of different moral value and ontological significance.
This was possible because, despite its internal divisions, the committee Warnock had adopted skepticism as its official position: it declared itself incapable of deciding about the nature of the early human embryo, opted not to attempt to define what the human embryo is, and limited itself to giving criteria about how to treat these unknowns. Thus says report Warnock, in a decisive passage for our topic today: Although it might seem that questions about when life and personhood come into existence are factual questions susceptible of straightforward answers, we submit that these questions are in fact complex amalgams of factual and moral judgments. Rather than attempting to answer these questions directly, we have chosen to go straight to the question of how the human embryo is properly to be treated.
The committee held its nose at the offensive smell of factual and moral judgments, and the fourteen-day sentence was enunciated. This had, astonishingly, a spectacular acceptance in the scientific establishment. It has leapt into almost every piece of legislation enacted so far. It has provoked many philosophical and theological disputes.
Once the arbitration decision of his President was accepted, the committee Warnock had to look for reasons to support it: the committee renounced to any philosophical argumentation, always conflicting, and preferred to give it a biological foundation, more acceptable and universal. He does so precisely in Chapter 11 of report, graduate Scientific Problems: Human Embryos and research.
It describes concisely how the initial human development is made: fertilization, on day one; segmentation and training of the morula, as the embryo passes through the tube, over the next three days; the training of the blastocyst, on day five, when the embryo reaches the endometrial cavity; the initiation of nesting on the sixth day, which is completed in six or seven days, while a lively activity of proliferation and cellular displacements takes place, giving rise, on the one hand, to the enveloping Structures , which will form the placenta and the fetal membranes, and, on the other hand, to the inner cell mass, from which the embryonic disc and the embryo itself are derived. All this is a matter of elementary classical embryology.
The report now introduces his interpretation of the individuation process. Not only the initial cell, the zygote, but also the two - and perhaps also the four - first blastomeres that result from the segmentation of the zygote, retain their totipotent character and are, therefore, each capable of developing an independent embryo. The capacity to split in two is maintained throughout the immediate posterior development , up to day 14 or 15 after fertilization, since it is possible that a blastocyst or an embryonic disc may split in two, separate and give rise to two twin embryos. It is even possible that two primitive lines are formed in a single embryonic disc: this is the latest stage in which the training of identical twins can occur. After day 14 or 15, embryonic cleavage is no longer possible: the individuality of the embryo is definitively fixed.
In the opinion of committee, the fixation final of individuality, reached at 14 days, offers a solid biological basis to sustain the dignity and ethical respect of the embryo, and also to point out an unequivocal limit, beyond which destructive manipulation is not admissible. In tune with the ethical agnosticism of committee, its proposal is not based on any of the metaphysical speculations that circulate in the world about the beginning of life and the dignity of man. The committee supports in a merely biological fact the borderline between what is authorized and what is forbidden, but does not bother to refute the objection to using human embryos in research of those who claim that each one of them is, from the first moment, a human being. In the opinion of committee, only from day 14 onwards is the embryo protected. Before that age, the human embryo is an undefined entity that does not demand ethical respect from us.
The biological justification for such a decision is literally this: A singular reference letter point in the development of the human individual is the training of the primitive line. Most authors place it around day 15 after fertilization. Taking that time as a limit also coincides with the opinion of those in favor of the end of implantation as a time limit. We have therefore considered that a date immediately prior to that time would be a desirable moment as the final deadline of the research.
Fortunately, the decision was made at the last possible moment: on the 14th.
Does the biological soil withstand the weight of ethical construction?
What factual support does this Solomonic decision receive? What statistical force is behind such a transcendent judgment? How many uniovular twins are formed, day by day, throughout those first 14?
I ask this question because committee Warnock, shying away from any philosophical argument, wants to base his rule on data empirical. I have the impression that either the argument was not analyzed as to its statistical strength, or if it was, it has been attributed a magical force.
Let us look at some data on the frequency and chronology of the process of uniovular twinning. It is a fascinating question, on which much progress is being made, so much so that no definitive conclusions can be drawn. I think, however, that they are worth taking into account in order to critically evaluate the decision of committee Warnock and that of so many legislators, physicians and philosophers who have made it their own.
In contrast to the higher frequency and variability of dizygotic twinning, monozygotic twinning is less frequent and variable. The rate of uniovular twinning is fixed at around 4 per thousand gestations. This figure refers to advanced gestations, detectable in prenatal check-ups performed by pregnant women. data is being collected, leading to the suspicion that the issue of twin pregnancies may be higher in the first weeks of pregnancy than previously estimated, since it seems that one of the twins is often lost at that time: it has recently been stated that only one in 10-12 twin pregnancies (di- and monozygotic) ends with the birth of both twins: in the others only one of the twins is born, since the other is lost. This fact is awaiting confirmation and, for our interest, to know if it affects monozygotic and dizygotic twins equally. In any case, and pending confirmation of these data data, let us take as a starting point for our calculations that the rate of monozygotic twins is between 4 per thousand of births and 4 per hundred of conceptions.
Our next question concerns when, between day 1 and day 14, monozygotic twinning takes place. We have to answer it with the data available to us. The data could be better if obstetricians would take care to examine with different techniques, especially by studying the structure of the fetal envelopes, which reliably mark the moment of twinning, and not only at the time of delivery, but also beforehand by means of high-resolution ultrasound. Well, 98 percent of monozygotic twins have subject diamniotic-dicorial or diamniotic-monochorial envelopes, which means that they are produced by fission of the initial blastomeres or by cleavage of the blastocysts before the amnion is formed. Ninety-eight percent of monozygotic twins are therefore before the end of the first week.
It is time to do the math. If the incidence rate of monozygotic twinning is between 4 percent and 4 per thousand pregnancies, it seems rather risky to make such a serious moral decision as not granting degree scroll respect to an entire class of human beings because such a small fraction of them deviate from the rule. This is a collective grievance of great magnitude. The members of the committee Warnock do not seem to have been inspired by a criterion of "biological" justice when, because of a very few, they punished many. The incongruity seems even greater if we consider the fact that, on the quantitative instructions , a much greater harm is inferred to the embryos of the second week than to those of the first week. In the course of the second week, 2 percent of the 4 percent or 4 per thousand, that is, eight out of ten thousand or eight out of one hundred thousand embryos, deviate from the standard rule (one zygote-one embryo). Extending the arbitrary date of respect for the human embryo to 14 days, instead of 7 days, has little rational statistical basis.
For it is no good erecting as a rule what is a rare exception. I think I can conclude that Baroness Warnock's decision to set the age of 14 days to command and prohibit, to separate what is a good deed from what is a harshly punishable crime is as capricious a decision as any other, in the sense that it lacks scientific validity and rational justification. The words of the Warnokian sentence are solemn, though empty:
Accordingly, we recommend that no human embryo derived from in vitro fertilization, whether frozen or not, may be kept alive, if not transferred to a woman, beyond day 14 after fertilization, nor may it be used as a subject of research beyond day 14 of fertilization. This 14-day period does not include the time during which the embryo may remain frozen. We further recommend that the manipulation or use of live human embryos derived from in vitro fertilization beyond this limit be declared a crime. We recommend that no human embryo that has been used for research be transferred to a woman.
Despite its lack of biological basis, the recommendation of the report has passed to the medical internship , to the statutory and legal norms, to the regulation of the scientific research . We have to admit it: the 14-day rule has triumphed, it has been imposed as legal and professional orthodoxy. Has it received, perhaps, some support from Philosophy - mainly ontology and ethics - and theology?
With some variations in detail, more than a few bioethicists, philosophers and theologians, including those in the Catholic camp, propose the hypothesis that the human embryo is not a person at the moment of conception and that it only acquires the condition of personhood around day 14. Others demand that the unborn must have acquired fuller human characteristics, such as an external form similar to that of a child, offer detectable bioelectrical signs of brain activity, possess self-consciousness, or others. We are now concerned exclusively with the individuation hypothesis.
Interestingly, the hypothesis does not start from metaphysical notions, but from two biological concepts: monozygotic twinning and the training of genetic chimeras.
It is said, on the one hand, that a young embryo can split and that each resulting fragment continues its development to become a separate human organism. It is clear that persons are presented to us as individuals, each one has an individual identity, which means that it cannot split and become two or more persons. It follows that the embryo, as long as it is capable of splitting, is not yet a person, a human individual. Only later, when from day 14 onwards it loses its capacity to divide, the embryo acquires the status of a human individual, and then becomes capable of becoming a person.
It is said, with regard to the training of chimeras, that it is possible for two very young embryos to fuse and thus form an embryo whose cells present different genetic endowments. Given the impossibility for two persons to fuse to form a single person, it can be concluded that at the stage when the chimerical fusion of two embryos is possible, these have not reached the individuation that enables them to become persons.
Many authors have succumbed to the elegance and simplicity of this argument, since it seems quite reasonable to accept that an entity that is divisible cannot continue to exist once it has been divided, since it does not possess as a subject the necessary continuity of existence; that is, it is not a subject, because it cannot be said to be the same before and after the change. Some authors identify the human subject staff with the immortal and indivisible soul. And they add to their argument by saying that, if the embryo is divisible, it is not an individual human subject, and therefore lacks a human soul: it is therefore not a member of our family, one of us. Consequently, it cannot demand the protection of its life and dignity to the same extent that we demand it.
The refutation of the individuation hypothesis has been made by several authors. In what follows I will follow the arguments and data of Teresa Iglesias and John C. Gallagher. The former says two important things:
One, that we do not know in sufficient detail and depth the biological processes that, in the human species, lead to spontaneous, unprovoked monozygotic twinning at laboratory. And we know even less about the chimeric recombination of two complete embryos, never observed in the human species, and probably not in other mammalian species either. This lack of knowledge should incline us to consider that, in principle, theories based on partially unknown data are merely speculative. Fusion and recombination of blastomeres from early embryos of the same or related species has been achieved in laboratory under very specific conditions. It would be imprudent to rely on such data artificial biology and the unlikely or very leave spontaneous occurrence of chimeric fission and recombination to construct important personal moral decisions or to inform the laws that are to govern the political community.
Two, that the hypothesis of individuality has convincing force only for those who see the embryo through the prism of mechanistic Darwinism or Cartesian dualism: they see the first juxtaposed elements, accumulated cells, but they do not see the embryo properly.
The early human embryo cannot be considered as an ontologically and biologically undifferentiated being, whether from the molecular, cellular, morphological or entitative point of view. It is, in an unavoidable way, the child of a man and a woman, it belongs to the human species, it is determined in its sex, it is genetically a unique and individuated entity. The increasingly fine-tuned research of gene activation is revealing to us from year to year new aspects of the very early and programmed molecular activity that occurs from the very first moment in the zygote and in the initial blastomeres. The unfolding of the genetic program of development, dynamically written, in the embryo is not only species-specific, but individually exclusive. As Teresa Iglesias says, the embryo knows where it is going. Holbrook speaks of a primordial biological consciousness that guide the development of the embryo.
Classical embryology had already discovered, thanks to programs of study of the pioneers of ontogenetic experimentation, that the cells of embryos can disaggregate and recombine, be transferred within the same embryo or transplanted from one to another. They had come to the conclusion that there are mosaic eggs and regulatory eggs. In the former, the destinies of the initial blastomeres are already rigidly prefixed, so that the injury or destruction of one of them, for example, the one from which the right half of the animal is to be derived, is followed by the absence of the corresponding part of the embryo. In regulatory eggs, the initial blastomeres are totipotent, so that the destruction of any one of them is compensated by the activity of the remaining ones, which give rise to a completely normal embryo: the risk of strongly damaged individuals being born is thus overcome.
Artificial twinning -the embryonic fission experiments of Hall and Stillman, which raised so much noise two years ago- or those of embryonic recombination -of blastomeres of mice of different breeds, or of blastomeres of related species, the sheep, the geeps, from Cambridge - are the experimental exploitation of this regulatory capacity that the initial embryos possess and that restores them to normality in case of having suffered some damage or loss of some of their cells or that allows them to integrate or assimilate their own stray blastomeres or the blastomeres of another embryo that the experimenter transfers to it or that another embryo that enters contact with it yields to it.
In other words, in the very young embryo the capacities for repair, regeneration, incorporation of transplants or cell transfer are already present. Thanks to the fact that, fortunately, in adult organisms some of these properties are retained, although notably diminished, we are able to recover from many cell losses and to be donors or recipients of transplants.
In fact, every living being is generated as a whole and develops as a whole, which, of course, does not alter the fact that we can interfere with its totality. An embryo can withstand a tremendous amount of manipulation and, in spite of it, survive, as the daily activity of in vitro fertilization centers reveals.
What has this to do with the argument of individuation? We have abundant empirical evidence to conclude that, from an organic point of view, a living being cannot be divided as the whole being that it is, as a living unit, without perishing at business. Because each living being is a whole composed of parts (cells, organs), it can be organically manipulated, it can be disaggregated, it can be re-aggregated, it can be recombined. But what is disaggregated, re-aggregated or recombined are not the complete living beings as such, but their parts. If, for example, a blastomere is separated from a four-cell sheep embryo, placed in an artificial zona pellucida and allowed to develop on its own in the uterus of a sheep, it gives rise to a sheep that is identical to the one that can be born from the other three blastomeres of the original embryo. The isolated cell was part of an embryo which, separated, becomes a complete new being that is a new self. Before the separation, that cell was a genuine, authentic part of an embryo, which functioned as part of it, integrated in it and related to it as a part of the whole. That is why we say it is totipotent, i.e., that a cell of an initial embryonic being has the capacity to become a whole if it separates from it. But the cell, while integrated in the whole, while playing its role as part of a whole, is not a whole, but only a part of it.
The general relationships that can be established between living beings as totalities could be summarized as follows:
a. A living being is an organic whole. As such, it can detach parts (cells, organs) that can be integrated into other organisms. This is an expression of donation and transplantation capabilities.
b. A living being can detach parts (cells) that can become new living beings, all new and independent, either by themselves or by combining with other cells. This is an expression of the capacity for asexual and sexual generation.
c. A living being can suffer deprivation or destructive injury to some of its components (cells) and be able to compensate or internally repair the defect and continue to live and develop as a functioning whole. This is an expression of its regulatory, repair and regenerative capacities.
d. A living being, as a living whole, neither occurs in other living beings nor fuses with another living being, but some of its parts are capable of doing so. This is an expression of the fission and recombination capacity of the cells of that organism.
There can thus be fragmentation in a living being that is at the basis of asexual generation. But there is no fusion or splitting of living beings as total entities. Thus, since fusion or splitting of beings as total living beings is not possible, there is no possibility of the existence of embryos that are unstable in terms of their individuality. Stability is a property of individuality. Stable individuality remains a permanent feature of every living being considered as a whole, even under conditions, naturally or artificially induced, that make externalize, sometimes in a spectacular way, the capacities of donation, reception, generation, repair, regeneration and regulation mentioned above.
Each living being is an individual differentiated in its specificity and uniqueness, that is, it is organically individuated from conception to death. The initial embryo, as a living whole, is a stable individual organism. Its cells enjoy, at this stage of their existence, amazing capacities that make them very different from our cells. But as individual beings, they are already our little brothers and sisters, they are ourselves when we were like them.
I know that, at this moment, in Argentina there is a lively discussion around the legislation of assisted reproduction. This symposium is a contribution to the social discussion on a tremendously controversial, almost divisive topic . Legislators and the public have a formidable occasion to confront the fundamental question of who each of us is, how we begin our existence, what are the ethical conditions that should surround the transmission of human life, the truly human ways of procreating.
Human embryos should be represented in this discussion. They have no voice to intervene in the discussion, nor vote to participate in the decisions that so deeply concern them.
But they tell us that, like them, we have all begun our existence under the humble appearance of an embryo, that our biography has that minimal and, at the same time, glorious beginning. We have all been unicellular embryos and, having been so, we have become capable of being what we now are. To deny human embryos the right to full humanity is a cruel injustice; it is to deny ourselves our origin. It is perverse to admit that one is not human in those 14 days: it gives, obviously, certain advantages, but it is equivalent to saying that, during a certain time of my life, I lacked importance, I was a non-existent, someone without rights, because letting me die or kill me was simply a discretionary and arbitrary matter.
Every human being is engendered under the appearance of a cell. The day this happens, it reaches the highest concentration of humanity and dignity per unit volume. Ten years of reading arguments in favor of the warnockian thesis have not convinced me that it was not me, with all my rights and my destiny, who began to live the day my parents begot me, the day God created me in his image and likeness: a single-celled, microscopic image for the moment, but full of power and meaning, invited to live a singular and unrepeatable human destiny.