Zygotes and Embryos are People

Anthony Zimmerman
Published in Homiletic and Pastoral Review
June, 2000
Reproduced with Permission

The Magisterium of the Catholic Church teaches with unmistakable clarity that from the moment a human zygote has formed we owe it the unconditional respect that is morally due to that human being. The new Catechism declares that a human body is human precisely because it is animated by a spiritual soul (364). In other words, a human body does not begin without a human soul.

Unconcerned with decent respect for human life, in vitro fertilization, with its karma of selecting, destroying, and discarding human embryos, is now an established business. Experimentation with human embryos and embryonic stem cells follows in its wake. Ironically for the Church, several notorious dissenting priests attempt to justify such action by alleging that humans are not yet people for some weeks after fertilization. Another rationalization was given by a doctor who said to me: "Sure, it's a human being, but we don't have to give him or her a visa."

Canon 1398 rules that those who do abortions march themselves out of the door of the Catholic Church. It reads: "A person who actually procures an abortion occurs a latae sententiae excommunication."

The thrust of this writing is that the Church should now extend Canon 1398 to traffickers in human zygotes and embryos.


The CDF, with the Pope's approval, declared in 1987 that a new human life begins at fertilization:

This congregation is aware of the current debates concerning the beginning of human life, concerning the individuality of the human being and concerning the identity of the human person. The congregation recalls the teachings found in the Declaration on Procured Abortion:

"From the time that the ovum is fertilized, a new life is begun which is neither that of the father nor of the mother; it is rather the life of a new human being with his own growth. It would never be made human if it were not human already. To this perpetual evidence ... modern genetic science brings valuable confirmation. It has demonstrated that, from the first instant, the program is fixed as to what this living being will be: a man, this individual man with his characteristic aspects already well determined. Right from fertilization is begun the adventure of a human life, and each of its great capacities requires time ...to find its place and to be in a position to act" (Declaration on procured Abortion, 1974).

Note the wording that a new human life begins at fertilization. The next sentence states that a human zygote is a human individual: "In the zygote (the cell produced when the nuclei of the two gametes have fused), resulting from fertilization, the biological identity of a new human individual is already constituted."

Nevertheless the Magisterium chose, in 1987, to not commit itself to a philosophical affirmation:

Certainly no experimental datum can be in itself sufficient to bring us to the recognition of a spiritual soul; nevertheless, the conclusions of science regarding the human embryo provide a valuable indication for discerning by the use of reason a personal presence at the moment of this first appearance of a human life: How could a human individual not be a human person? The magisterium has not expressly committed itself to an affirmation of a philosophical nature, but it constantly reaffirms the moral condemnation of any kind of procured abortion. This teaching has not been changed and is unchangeable.

Five years later, however, the Catechism of the Catholic Church states forthrightly that a human body is such precisely because a spiritual soul animates it:

The human body shares in the dignity of "the image of God": it is a human body precisely because it is animated by a spiritual soul, and it is the whole human person that is intended to become, in the body of Christ, a temple of the Spirit.

The Latin of the emphasized part reads: illud est corpus humanum praecise quia anima spirituali animatur. Note the logic of the statement: If the body is human, then it has a soul. In other words, there is no zygote or embryo which is human that is not animated by a spiritual soul. If there is a spiritual soul, then this zygote is a person. If this is a person then God has created that person's soul. Anyone who now dares to teach that the human zygote is not yet a human person contradicts the Catechism and trifles with a person created by God.

It should not be difficult to accept that human life begins as a single cell zygote. You were once a zygote, I was once a zygote, the Pope was once a zygote. Had someone killed those zygotes, neither you nor I nor the Pope would be alive today. The fact that the Church baptizes infants, following the Tradition of the Apostles, indicates that she believes them to be persons. She affirms with reason and common sense what the microscope cannot ascertain.

The Congregation insists that we have a moral obligation to respect the zygote as a person:

Thus the fruit of human generation from the first moment of its existence, that is to say, from the moment the zygote has formed, demands the unconditional respect that is morally due to the human being in his bodily and spiritual totality... Since the embryo must be treated as a person, it must also be defended in its integrity...

Let us hope that the Church will speak with more power by excommunicating intractable offenders.


Both gametes have undergone specific preparation to be ready for fertilization. As in the somatic (body) cells, each immature sex cell contains 46 chromosomes - the number that is specific for an individual of the human species. Before being able to take part in fertilization, both immature sex cells must cut the number of chromosomes in each cell in half (23). This is accomplished by the process of meiosis. In the female, at about the fifth month of fetal growth, the oogonia begin the first phase of meiosis but do not complete it. "They remain in meiotic arrest as primary oocytes until sexual maturity" (William J. Larsen, Human Embryology, New York: Churchill Livingstone, 1997, p. 4).

The first phase of meiosis is completed when the oocytes mature after puberty, in preparation for ovulation. Then "This oocyte enters a second phase of meiotic arrest and does not actually complete meiosis unless it is fertilized" (Larsen, ibid.). The oocyte is fragile now in a suspended condition at metaphase. If not rescued by a spermatozoon "which triggers the oocyte to complete its meiosis) within 24 hours after ovulation, it will perish, having lost its chance forever. The spermatozoon, on the contrary, has completed its twofold meiosis prior to leaving the man's body. It is ready for fertilization, since by means of meiosis it has already cut the number of chromosomes in half.

When a spermatozoon docks with an oocyte at fertilization, the oocyte goes into immediate action. It prevents entrance of other spermatozoa by producing a chemical change in its zona pellucida. The oocyte also finally completes its second phase of meiosis. When the spermatozoon has completed penetration into the cytoplasm of the oocyte, the walls of the nuclei open and the DNA interacts. This is now a zygote. Then the first cell division occurs. One of the two then divides again and there are temporarily three. The second divides eventually and there are four. Life is on its way through programmed sequences.

Just when does "fertilization" occur, at first contact, at docking, at penetration, or at the initial interaction of DNA? I lean toward the position that it occurs at the instant of successful biological "docking" or interlocking of a spermatozoon with a secondary oocyte. From that point of time the two gametes are joined and begin to operate biologically as one single unit. When space ships dock, bolts snap into place to keep them together. When nature docks a spermatozoon and an oocyte, God creates a new person.

At any rate, fertilization has definitely occurred when the single cell zygote exists. It grows as a human being, has specifically human proteins and enzymes, and it follows the genetic program for building a human body. Because it is a human body, it is enlivened by a human soul, is created by God, and is off limits to human manipulation by God's command: "Thou shalt not kill."


Space ships accelerate in a power flight until they achieve orbit. Humans lift themselves into life by one continued process of growth, from zygote, to birth, to maturity. Geneticist Jerome Lejeune described how the human DNA builds the life of this body:

Nature, to carry the information from father to children, from mother to children, from generation to generation, has used the smallest possible language. And it is very necessary because life is taking advantage of the movement of particles, of molecules, to put order inside the chance development of random movement of particles, so that the chance is now transformed according to the necessity of the new being.

All the information being written, it has to be written in the smallest language possible so that it can dictate how to manipulate particle by particle, atom by atom, molecule by molecule. We have to be with life at the real cross between matter, energy and information (Testimony, August 10, 1989, before the Circuit Court for Blount County, Tennessee, printed by Michael I Woodruff, Director, Center for Law and Religious Freedom, Annandale, Virginia, p.39).

The DNA is blue print, boss, and construction team simultaneously. It biologizes particles, atoms and molecules into living tissues and functioning organs, and integrates growth as one coordinated process. The construction blocks - particles, atoms, molecules - manipulated into place by life, are identical. These blocks could even be interchanged between human bodies and animal bodies without altering anything whatsoever. They are like bricks in a wall laid in place by a bricklayer. Dr. Lejeune illustrates how life differs from building blocks:

A chromosome is very comparable to a mini-cassette, in which a symphony is written, the symphony of life. Now, exactly as if you buy a cartridge on which Eine Kleine Nachtmusikfrom Mozart has been registered, if you play it in a normal recorder, the musician would not be reproduced, the notes of music will not be reproduced; they are not there; what would be reproduced is the movement of air which transmits to you the genius of Mozart. It's exactly the same way that life is played. On the tiny mini-cassettes which are chromosomes are written various parts of the opus which is for a human symphony; and as soon as all the information necessary and sufficient to spell out the information necessary and sufficient to spell out the whole symphony (is there), this symphony plays itself; that is, a new man is beginning his career (op. cit., p.41)


The tiny change on the DNA, continued Dr. Lejeune, changes the surface of the big groove of the helix of DNA; inside of this big groove some proteins will hook on different segments specific of the DNA. This is a kind of language of instructions. It tells the chromosome: "Speak here; give this information here; but be silent there; don't pass on that information." There is simply too much information in ourselves to allow them all to speak at once, telling all they know. Some genes must remain silent while others speak.

We believed for years, continued Dr. Lejeune, that the chromosomes of human males and females are identical. Now we know that the DNA carried by the sperm is not underlined, or not crossed out by methylation in the same places as in the DNA carried by the ovum. Underlining or deleting is not done in the same way in the male chromosome and its equivalent female chromosome. When male and female unite, some information is to be read as coming from the male chromosome, some from the female.

When the original human cell, the fertilized ovum, divides into two cells, that written information goes from one cell to the other: "When it's split in two we know that exchange of information comes from one cell to the other. When it's split in three it receives information: "We are an individual." [Dr. Lejeune had explained that the original cell splits into two cells; one of the two then splits again, and there are three. After some time, the other also splits, and there are four.]

And when the cleavage continues progressively, the underlining and deleting is progressively changed so that the cells differentiate, becoming specialized "doing a nail, doing hair, doing skin, doing neurons, doing everything." In the first cell not only the entire genetic message was there in the way it is still in every cell; the first cell also had written in it the sequences, how they are to be read one after another (Lejeune, op. cit. pp. 45-47)..

Dr. Lejeune goes on to show how male and female gametes are complementary to each other, building up the body and its parts by cooperative action. When two male nuclei are inserted into an ovum from which the female nucleus has been removed, the sequential program does not move forward to build an entire body; instead it produces an androgenote, little cysts which look like the chorion and placenta. Two female nuclei make spare parts, pieces of skin, of teeth, little nails. In other words, when not sequenced properly by preprogrammed methylization of paternal and maternal gametes, the ability to build a viable body is not there.

The long and short of genetic science, therefore, is that human life develops as one continuum from zygote to maturity. There is no finding there of delayed personhood. If twinning occurs, we may assume that the initial person remains alive while a second person also comes to life.

Why should anyone argue that the zygote is no person because his or her twin may also come to life later?


Seminarians ought to receive correct biological information about how human beings begin, so that when they become our priests and bishops they have the mental capacity to make correct moral judgments about responsibilities toward human life. Seminarians at the Tokyo Catholic Theological Seminary, unfortunately, are going to get facts about when life begins all wrong, if they believe what their current Professor of Moral Theology wrote some years ago. To date the Professor has not retracted publicly what he wrote in Koe magazine in 1987:

We must distinguish between a human life and a human being...The fertilized ovum is programmed genetically to become an individual body, so that it has definitely begun its process towards individual human life. In other words, at this stage the fertilized ovum cannot yet be called a human person...

However, at what point of time one can speak of a human person "with a heart" is a problem whose solution is very, very difficult, and neither science nor philosophy can find its way to draw a line ("The Vatican and Reverence for Life," Koe,August-September 1987; translated from Japanese by the present writer).


The Tokyo Morals Professor, lacking scientific backing, appeals to other priests rather than to scientists for confirmation, as though more decibels would confirm his affirmation:

Moral theologian McCormick uses the term nascent human life (human life in formation). He does not call it individual life. Curran says that during the first 2 - 3 weeks after fertilization one cannot speak of this as being truly human in a strict sense. De Janni, K. Rahner, and various other Catholic theologians express doubt about whether a fertilized ovum can be called a human being with a heart before a month has gone by after fertilization took place...As Haering states, there is an area of obscurity during the interval from conception to personalization (Koe article).

Unfortunately, it is true that "Moral theologian McCormick" [not an embryologist] uses the term pre-embryo which embryologists rightly reject:

The Rev. Richard McCormick, writing in the Kennedy Institute of Ethics Journal, now questions the judgment of the Catholic Church relative to the time of ensoulment from conception to sometime later in development ("Who or what is the pre-embryo?" KIE Journal, 1991, 1:1-15). He uses the term pre-embryo which is not an established embryological term (The Human Development Hoax, C. Ward Kischer, Ph.D., Dianne N. Irving, Ph.D., second edition 1997, p. 23; distributed by American Life League, Stafford, Virginia).

Kischer has taught human embryology to medical students, upper division and graduate students since 1960. Irving worked for seven years at the National Institutes of Health, Cancer Institute, as a career-appointed research biochemist and obtained her doctorate in Philosophy from Georgetown University. Both are thoroughly familiar with the current attempt to make experiments with embryos and human cloning legal, and with the people and issues concerned. In their book The Human Development Hoax they point out the immense mischief now being done by the invented term pre-embryo which has no foundation in scientific embryology, but was created arbitrarily.

Embryologist Kischer denies the validity of the term pre-embryo. He brands it as "The big lie in Human Embryology" and points out that professional embryologists do not recognize such a stage of development (Kischer-Irving 73). Father McCormick bases his use of the term on Clifford Grobstein who used it in 1979. Clifford used the term to defend Edwards and Steptoe who had employed external fertilization techniques which resulted in the birth of Louise Joy Brown in 1969. The term was invoked not on the basis of observed human development, but as a political ploy to gain acceptance of in vitrofertilization. Kischer deals with pseud-arguments of Grobstein to justify the term, and points out that professional embryologists reject it (pp. 74-80). Irving likewise refutes arguments by Father Norman Ford and others that there is an "biological individual" present at fertilization, but rational ensoulment does not occur until later (pp.141-155).


Dr. Irving points out (pp. 147 ff.) that the Supreme Court realized that if the human fetus were to be recognized as a human person, then it would have a right to life under provisions of the Fourteenth Amendment. The Court therefore decided that no one knows when life begins: "We need not resolve the difficult question of when life begins. When those trained in the respective disciplines of medicine, philosophy and theology are unable to arrive at any consensus, the judiciary, at this point in the development of man's knowledge, is not in a position to speculate as to the answer." They conclude that the human fetus is only "potential human life", or a "potential person".

The High Court's decision notwithstanding, continues Irving:

There is absolutely no question, scientifically, when the life of a human being begins. It begins at fertilization. That is a scientific fact and represents a scientific consensus. This remains true no matter what philosophers, bioethics or theologians, throughout all of the ages or from all cultures, try to proclaim. The proof is under the microscope. There is also no such thing, as was assumed and declared by this Court, as a human embryo or a fetus who is a "potential human life," or a "potential human person." There is, to the contrary, an already existing human being with the potential to grow and develop further.

By their action, the Court has established what they want us to believe to be an insoluble and "difficult" question. Consequently, the Court saw fit to impose certain specific philosophical, bioethical and theological opinions about "delayed personhood" on the entire country, in the guise of a "neutral"or "consensus-driven" public policy (Kischer-Irving, p. 219).

The Court's fudging about when human life begins is pursued today in attempts to justify research that costs the lives of human embryos, and research on embryonic stem cells which are obtained at the cost of the lives of embryos. "The National Institute of Health, Human Embryo Research Panel has already issued its recommendations, basing them on their conclusion that the `pre-implantation human embryo...does not have the same moral status as infants and children." Furthermore, these theories of "delayed personhood" are precisely those of Grobstein, McCormick and others, referenced in the Panel's recommendations (Kischer-Irving, 222).

The term pre-embryohas become an automatic death sentence for innocent humans:

According to Grobstein and McCormick, "pre-embryos"are merely "genetic individuals" and not "developmental individuals" yet, and therefore they are not "persons". Since they are not legitimate full-blown "persons" yet, they do not have the moral or legal rights and protections that actual human persons possess (and therefore these "pre-embryos" could be aborted, experimented with, disposed of, etc.) (Kischer-Irving p. 39).


Canon 1398 reads: "A person who actually procures an abortion occurs a latae sententiae excommunication."

Because the rights of zygotes and embryos are being violated routinely and on a vast scale, and because several priests and seminary professors notoriously dissent from the Church teaching about reverence for life from the time of fertilization, the writer hopes that the Church will see fit to apply Canon 1398 to those who wantonly treat human zygotes and embryos as though they were less than human beings. Such action would, hopefully, motivate these priests to cease and desist from promoting their homemade theology.