Condic's 'Pre-Zygote' Error in 'When Does Human Life Begin?'
"A small error in the beginning leads to a multitude of errors in the end" (Aristotle, De Coelo)

Dianne N. Irving
©Copyright November 18, 2008
Reproduced with Permission

This article is copyrighted and thus must be acknowledged when using its original ideas and resources or quoting from it.

[Note: The scientific facts of human embryology presented in this article by Dr. Dianne Irving, and specifically when during the process of fertilization a new human embryo begins to exist, are accurate and in accord with the Carnegie Stages of Early Human Embryonic Development. -- C. Ward Kischer, Ph.D., Emeritus Professor of Cell Biology and Anatomy, specialty in Human Embryology, University of Arizona, College of Medicine.]

I. Introduction

As noted centuries ago by Aristotle, the Father of Biology, a small error in the beginning leads to a multitude of errors in the end. A similar caution is rightly made today by Fr. Richard John Neuhaus in his "Foreword" to Maureen Condic's recent White Paper, "When Does Human Life Begin? A Scientific Perspective":

"An honest debate about abortion, however, is about values based on facts. If we don't get the facts right, we will not get our values right. Establishing by clear scientific evidence the moment at which a human life begins is not the end of the abortion debate. On the contrary, that is the point from which the debate begins. ... It is a scientific examination of facts which, when clearly understood, provide the subject matter upon which other forms of reasonable reflection-medical, moral, legal, political, and theological -- can then be brought to bear. ("Foreword", in Maureen Condic, When Does Human Life Begin? A Scientific Perspective", The Westchester Institute, pp. v, vi; available at

Indeed, if we don't get the scientific facts right about when a human being begins to exist, then the very "starting point" for determining our values will be corrupted and invalid. It would also preclude a person from correctly forming his/her conscience on these related issues. As well, deliberations and conclusions on the medical, moral, legal, political and theological levels will be corrupted and invalid. In particular, when erroneous scientific facts are incorporated into laws and regulations, they create legal loopholes for others to use to "scientifically" justify essentially unethical actions. Legally, only what is specifically and formally defined in a particular law or regulation is covered; anything not specifically included in the legal definition would still be allowed. And needless to say, such legal (and scientific) chicanery has reached epidemic proportions today. A great deal hinges on the accuracy of those scientific facts.

More specifically, the use of inaccurate scientific facts of when a human being begins to exist would thus "scientifically" justify the unethical use of living human embryos - whether reproduced sexually or asexually, whether in vivo or in vitro - as unfettered biological "material" for human embryonic stem cell research, human cloning, IVF and other ART laboratory and clinical practices, all manner of human genetic engineering (including OAR, ANT, and iPS research), as well as the early destruction of these human embryos by the use of abortifacients, the production of vaccines, the testing of chemicals and biological products, etc.

Unfortunately, such unethical practices may be inadvertently advanced as the result of Dr. Condic's White Paper, unless critical scientific corrections are made - especially if such errors find their way into laws and regulations. The following comments are made with the greatest respect for Dr. Condic's work and that of the Westchester Institute, and are offered as helpful suggestions only. However, given the high stakes, not to comment would be remise.

But before addressing these concerns in more detail, it is suggested that one turn to the long-established objective scientific facts of human embryology as documented in Stage One of the Carnegie Stages of Early Human Embryonic Development, international standards that Dr. Condic never mentions in her White Paper. Often referred to as "the Bureau of Standards" of human embryology (O'Rahilly and Muller, p. ix), these are the standards that would be best to use as the determinative criteria for identifying when a human being begins to exist, not simply the "cell activity" standard that Dr. Condic employs. As we will see, "cell activity" is a necessary but not a sufficient standard to use.

II. Carnegie Stages of Early Human Embryonic Development: Stage One

a. Brief History of Development of the Carnegie Stages

For those unfamiliar with the field, human embryology is the scientific study of the material aspect of the developing human embryo and fetus with focus on the embryonic period, from the beginning of fertilization [or "when the matter is appropriately organized"] through 8 weeks (O'Rahilly and Muller 2001, p. 7). It has been systematically documented for sexually reproduced human beings in the Carnegie Stages of Early Human Embryonic Development since 1942.

It is important to note, however, that human embryos can be reproduced both sexually (by fertilization - both natural and artificial, such as in IVF in vitro fertilization and other artificial reproductive technologies) and asexually (as in naturally occurring human monozygotic identical twinning in vivo as well as in many different kinds of cloning and genetic engineering techniques in vitro). The immediate products of both human reproductive processes are new genetically unique individual living human beings, who immediately produce specifically human proteins and enzymes, and continuously form specifically human cells, tissues, and organs throughout development (Irving 1993b). Once normal human embryos are reproduced (whether sexually or asexually), their biological development would continue as described in the Carnegie Stages, developed many years ago by pioneers in the study of human embryology.

The first to systematically study human embryos was Wilhelm His (Anatomie Menschlicher Embryonen 1880-1885, 3 vols.), and the first to stage them was Franklin Mall in 1914. Later George Streeter (Streeter 1942, p. 211; Streeter 1945, p. 27; Streeter 1948, p. 143) laid down the basis for the currently used Carnegie staging system, which was completed by Ronan O'Rahilly in 1973 and revised by O'Rahilly and Muller in 1987. The Carnegie Stages are often referred to as "the Bureau of Standards" of human embryology (O'Rahilly and Muller 2001, p. 3). Today they continue to be verified and documented by the international Terminologia Embryologica (formerly, Nomina Embryologica) committee, which consists of more than twenty experts academically credentialed specifically in human embryology from around the world. After reviewing the latest research studies in human embryology, their deliberations were published in the international Nomina Embryologica, part of the larger Nomina Anatomica (now known as the Terminologia Embryologica, soon to be published as part of the larger Terminologia Anatomica). The Carnegie Stages themselves can be accessed online (available from

b. Carnegie Stage One

According to the Carnegie Stages, the embryonic period of the developing human embryo is composed of twenty-three stages. Of special note is Stage One - which, in sexual reproduction, begins when the sperm penetrates the oocyte and continues until just before the zygote starts its first cleavage cell division at syngamy (that is, when the pronuclear membranes surrounding the 23 paternally- and 23 maternally-derived haploid chromosomes in the single-cell embryo mingle and line up on opposite sides of the mitotic spindle fibers that appear in the zygote just before cell division). A great deal of human cloning and human genetic engineering takes place during Stage One of the developing human embryo, even before its formation as the zygote at the end of fertilization (or sometimes slightly later while the cells of the very early human embryo are still totipotent). It is Stage One that is particularly relevant to the scientific definitions and claims made in Dr. Condic's White Paper.

This White Paper brilliantly documents the functions and activities peculiar to the gametes and the new single-cell embryo during fertilization (pp. 3-5). It also notes the fact that at the beginning of fertilization, when the sperm penetrates the oocyte, a new living genetically unique individual single-cell human individual and human organism begins to exist (pp. 5-7). This conclusion is in accord with what the Carnegie Stages have documented since 1946 (and has been known scientifically for almost 130 years, e.g., in the work of Wilhelm His). According to the Carnegie Stages, "the characteristic feature of the embryo in Stage One is unicellularity; it is a single-celled organism." As succinctly documented further by the Carnegie Stages:

Embryonic life commences with fertilization, and hence the beginning of that process may be taken as the point de depart of stage 1. Despite the small size (ca. 0.1 mm) and weight (ca. 0.004 mg) of the organism at fertilization, the embryo is "schon ein individual-spezifischer Mensch" (Blechschmidt, 1972). ... Fertilization is the procession of events that begins when a spermatozoon makes contact with an oocyte or its investments and ends with the intermingling of maternal and paternal chromosomes at metaphase of the first mitotic division of the zygote (Brackett et al., 1972). (Carnegie Stages of Early Human Embryonic Development, p. 9, available from

The White Paper also rightly notes that once the human embryo begins to exist, its further biological development is continuous. All human embryologists would agree with this conclusion. As Dr. Kischer explains, the biological development of a human being is a continuous process: "[U]nder conditions we have come to describe and embrace as normal, all of development from first contact of the sperm and oocyte is a fait accompli" (Kischer 1993). And as emphasized by Swiss human embryologists O'Rahilly and Muller, "Despite the various embryological milestones, however, development is a continuous rather than a saltatory process ... " (O'Rahilly and Muller 2001, p. 8). O'Rahilly and Muller even use a direct quote from one of the pioneers of human embryology to that effect as the dedication of their 2001 textbook: "It is to be remembered that at all stages the embryo is a living organism, that is, it is an on-going concern with adequate mechanisms for its maintenance as of that time (Streeter and Heuser 1951, p. 165)."

These are the long-known and long-acknowledged objective scientific facts of when sexually reproduced human embryos begin to exist which have been and remain as the international standards used today. All human embryologists are professionally required to use them in their research and textbooks, and the Carnegie Stages are explained and displayed in those textbooks (e.g., see Kischer 1996 for a listing of human embryology textbook authors who consistently hold that, in sexual reproduction, human beings begin to exist at fertilization).

The problem arises when Dr. Condic refers to the new living human being formed at the beginning of the process of fertilization as the "zygote". The fact is that the zygote does not form until the end of the process of fertilization. Before that, the developing embryo is referred to respectively as "the penetrated oocyte" and the "ootid". Quoting directly again from the Carnegie Stages:

Fertilization, which takes place normally in the ampulla of the uterine tube [[fallopian tube]], includes (a) contact of spermatozoa with the zona pellucida of an oocyte, penetration of one or more spermatozoa through the zona pellucida and the ooplasm, swelling of the spermatozoal head and extrusion of the second polar body, (b) the formation of the male and female pronuclei, and (c) the beginning of the first mitotic division, or cleavage, of the zygote. ... The three phases (a, b, and c) referred to above will be included here under stage 1, the characteristic feature of which is unicellularity. (Carnegie Stages of Early Human Embryonic Development, p. 9, available from (emphases added)

[See also: Carnegie Stages online from University of Fribourg, Switzerland, "Human Embryology," 1999; also, Carlson 1999, pp. 24-37; Edwards et al. 1992, pp. 994-998; Gasser 2003; Irving 2008b and 2006; Kischer 1992, 1993, 1996 and 2003; Kischer and Irving 1997; Larsen 1998, pp. 12-14; Levron at al. 1995, pp. 653-657; Michelmann et al. 1986, pp. 243-246; Moore and Persaud 1998, pp. 34-37; O'Rahilly and Muller 2001, pp. 3, 7, 31-33, 19-35, Table 8-1, p. 89; Riley and Merrill 2005, p. 1; Sathananthan et al. 1991, pp. 4806-4810]

Given what is at stake, it is critical to investigate the implications of the author's error in more detail.

Next Page: III. Condic's 'Pre-Zygote' Error
1, 2