Carlos Bedate, S.J., a molecular biologist at a university in Spain, and Robert Cefalo, a doctor of medicine at the University of North Carolina, have written a provocative article in the Journal of Medicine and Philosophy in which they claim that the zygote (the one-cell stage of human life) is not a person. This claim has obvious ethical implications for moral discussion about morning-after-pills, intrauterine devices (which are abortifacients), and the disposal of extra zygotes formed in the process of in vitro fertilization (IVF).

Chaotic clump

The two scientists base their claim on the existence of a chaotic clump of cells that apparently began as a zygote, but is clearly not a human being. The mass of cells in question is called a “hydatidiform mole.”

Bedate and Cefalo state their case as follows: “the zygote can give rise to a biological entity that is not a person, e.g., the hydatidiform mole. Therefore, an individual zygote, even when biologically perfect, does not possess in itself all the necessary, and surely not sufficient information to become a human person.”

In the  same issue (December 1989), Thomas Bole of the Center for Ethics, Medicine and Public Policy at Baylor College of Medicine in Houston, Texas, writes an article that supports his colleagues’ view.

Bole also maintains that such a thing as the hydatidiform mole refutes the claim that personhood begins at conception. “Whether the zygote becomes one human individual or several, or a hydatidiform mole, is determined by forces outside the zygote and its informational capacity,” he writes.

Ironically, these three commentators agree with the delayed animation theory of St. Thomas  Aquinas. The thirteenth-century philosopher argued that the body must be appropriately prepared before the rational soul could be infused. Before this happens , according to Aquinas, two souls of a different nature shape the body: the so-called vegetable and animal souls respectively.


Aquinas, needless to say, knew nothing about genetics. Furthermore, the biology of his day had not developed beyond what it was during the time of Aristotle.

But the insights into human genetics gained by Dr. Jerome Lejeune of the University of Paris allow us to refute the claims made by Bedate, Cefalo and Bole. Their problem is ignorance of modern scientific facts.

In his testimony in defense of the right-to-life of seven frozen embryos which he gave in Maryville, Tennessee in August 1989, Dr. Lejeune provided some very important scientific facts about the zygote that modern genetics has only recently uncovered  (See ‘High-tech baby-making & the law’, The Interim, October 1990)

For some years, geneticists have been puzzled about the function of a methyl compound that is often attached to the DNA molecule. Recently, they have learned that this methyl compound blocks or silences the genetic information carried by the DNA molecule. Only where the methyl is absent is the genetic information free to express itself.

At the same time, scientists discovered that the genetic material carried by the male sperm and the female egg – these fuse to form a zygote – themselves have different methyl compounds. Therefore, DNA that is carries on all the chromosomes of male and female gametes is different. Before this discovery, it was believed that the egg and sperm differed. Before this discovery, it was believed that the egg and sperm differed only with regard to one pair of chromosomes – the so-called X and Y chromosomes which determine sexual identity.


Dr. Lejeune points out that only a false zygote can lead to a hydatidiform mole. These facts have been confirmed in genetic experiments with mice.

Says Dr. Lejeune: “We have discovered in those hydatidiform moles, there were only paternal chromosomes and the maternal pronuclei had died; we don’t know why. So, we know by the mice experiments that it is related  to methylation of DNA.”

In conclusion, the Bedate and Cefalo arguments is unconvincing. They wrongly assume that a true human zygote can produce a clearly non-human hydatidiform mole.

Recent insights into genetics reveal that the hydatidiform mole originates from a false zygote. Both maleness and femaleness are required for the true formation of a zygote. Maleness and femaleness alone, seen on an elementary genetic level, produce only chaos and disorder. To refute the existence of personhood in the true human zygote, as Bedate and Cefalo attempt to do, on the basis that it clearly does not exist in something that results from a false zygote is simply illogical.