What Happens to the “Extra” Soul? Split Embryos & Chimeras

One of the fundamental dogmas of Eastern Orthodoxy is the existence of the human soul.

In Orthodox spiritual circles, one finds the usual paradox of circular reasoning and confirmation bias when it comes to science. They love to boast when an early Church Father, or even Holy Scripture, mentions something that has only been verified by one of the sciences many centuries later. This gives an Orthodox Christian a warm feeling that this somehow proves the “Divine inspiration” of the texts. Of course, every religion has such instances of ancient texts containing truths that science has only recently confirmed—Judaism, Islam, Hinduism, Buddhism, most of the pagan religions—and modern-day adherents of these religions make similar boasts. One would assume that the Orthodox Christians who make such boasts believe in the validity of the science they claim validate the ancient writers’ divine illumination. However, this is only a case of confirmation bias.


However, when one of the sciences contradicts an orthodox teaching or dogma, then the Orthodox Christian resorts to a circular reasoning tactic: “True science validates Orthodoxy and the Scriptures because they are the only truth. If one of the sciences contradicts or seemingly disproves Orthodoxy then it is wrong because Orthodoxy is the only truth.” In some cases, the science will be dismissed abruptly as “an unproven theory” or “Western atheist propaganda.”

Thus, when a branch of science confirms some aspect of Orthodoxy or the Scriptures, the Orthodox Christian will say with a big smile, “Even science confirms this!” When it contradicts any aspect of the Orthodox faith then it is dismissed as secular and vain knowledge; not useful for the salvation of one’s soul.

Let’s return to the “eternal soul” in Eastern Orthodoxy. One of the central teachings of Orthodoxy is that a human embryo is a complete human being from the moment of conception; i.e., it is both body and soul. This dogma is used in bioethical arguments against abortion; i.e., a human being is murdered before the chance of baptism and enters the next life un-baptized. Furthermore, according to Elder Joseph Voutsas, abbot of St. Nektarios Greek Orthodox Monastery in Roscoe, NY, the Church Fathers teach that it is better for a woman to have the baby, baptize it, and then murder it over having an abortion. He also states the canonical penances for murdering a baptized baby are less severe for the mother than having an abortion.

Human Development Week 1: Morula to Blastocyst Stage

Split Embryos and Chimeras

A 3 day old embryo is a collection of 150 cells called a blastocyst. Embryos at this stage occasionally split, becoming separate people (identical twins). Is this a case of one soul splitting into two? But Orthodox dogma teaches that it is at the moment of conception that the embryo is body and soul. If the embryo splits, does one of them have no soul? Or is a new soul created after the moment of conception? Of course, the early Church Fathers were unaware of this fact; they were not illumined about this when they were writing their treatises about the human soul, their canons or their dogmas.

The early God-illumined Fathers were also unaware of the fact that sometimes two embryos fuse into a single individual, called a chimera. Neither the Orthodox Church nor her ancient dogmatic and scientific Patristic texts have an explanation of what becomes of the extra human soul in such a case. As a matter of fact, they are totally silent about these two physiological phenomenon.

Of course, now that science has revealed these happenings to the world, modern day theologians have been writing books and articles on Orthodox Christian bioethics. However, there is no general consensus and many of the authors have conflicting viewpoints.

Identical vs. Fraternal Twins

Embryo splitting may refer to:

  1. When spontaneous, the natural way in which identical twins are formed.
  2. When artificially induced, a method of cloning.

Monozygotic (MZ) or identical twins occur when a single egg is fertilized to form one zygote (hence, “monozygotic”) which then divides into two separate embryos.


Regarding spontaneous or natural monozygotic twinning, a recent theory proposes that monozygotic twins are formed after a blastocyst essentially collapses, splitting the progenitor cells (those that contain the body’s fundamental genetic material) in half, leaving the same genetic material divided in two on opposite sides of the embryo. Eventually, two separate fetuses develop. Spontaneous division of the zygote into two embryos is not considered to be a hereditary trait, but rather a spontaneous and random event.

Monozygotic twins may also be created artificially by embryo splitting. It can be used as an expansion of IVF to increase the number of available embryos for embryo transfer.

Here we have one fertilisation event, but two individuals result. Do those twins have to share the ‘human soul’ they had from conception?


Monozygotic twinning occurs in birthing at a rate of about 3 in every 1000 deliveries worldwide.

The likelihood of a single fertilization resulting in monozygotic twins is uniformly distributed in all populations around the world. This is in marked contrast to dizygotic twinning, which ranges from about six per thousand births in Japan (almost similar to the rate of identical twins, which is around 4–5) to 15 and more per thousand in some parts of India and up to over 20 in some Central African countries. The exact cause for the splitting of a zygote or embryo is unknown.

In vitro fertilization (IVF) techniques are more likely to create dizygotic twins. For IVF deliveries, there are nearly 21 pairs of twins for every 1,000.

Artificial embryo splitting or embryo twinning, a technique that creates monozygotic twins from a single embryo, is not considered in the same fashion as other methods of cloning. During that procedure, an donor embryo is split in two distinct embryos, that can then be transferred via embryo transfer. It is optimally performed at the 6- to 8-cell stage, where it can be used as an expansion of IVF to increase the number of available embryos. If both embryos are successful, it gives rise to monozygotic (identical) twins.

Such an individual results when fraternal twins, derived from separate conceptions, merge very early in development to form a single individual with some cells with one genome and some cells with another


A chimera is an ordinary person or animal except that some of their parts actually came from their twin or from the mother. A chimera may arise either from monozygotic twin fetuses (where it would be impossible to detect), or from dizygotic fetuses, which can be identified by chromosomal comparisons from various parts of the body. The number of cells derived from each fetus can vary from one part of the body to another, and often leads to characteristic mosaicism skin coloration in human chimeras. A chimera may be intersex, composed of cells from a male twin and a female twin. In one case DNA tests determined that a woman, mystifyingly, was not the mother of two of her three children; she was found to be a chimera, and the two children were conceived from eggs derived from cells of their mother’s twin.

Mosaicism and chimerism



“The epidemiology of multiple births”. Human Reproduction Update (European Society of Human Reproduction and Embryology) 5 (2): 179–187. http://humupd.oxfordjournals.org/content/14/1/37.full

“Study: Twins form after embryo collapses”. USA Today. http://usatoday30.usatoday.com/news/health/2007-07-03-52152171_x.htm

“How eggs split to form identical twins” WonderQuest. http://usatoday30.usatoday.com/news/science/wonderquest/2001-05-09-why-twins-form.htm

“Human embryo twinning with applications in reproductive medicine” http://apps.elsevier.es/watermark/ctl_servlet?_f=10&pident_articulo=90018480&pident_usuario=0&pcontactid=&pident_revista=605&ty=147&accion=L&origen=zonadelectura&web=www.elsevier.es&lan=en&fichero=605v93n02a90018480pdf001.pdf

“Projections of population-based twinning rates through the year 2100” http://www.reproductivemedicine.com/toc/auto_abstract.php?id=13594

“Time-lapse recordings reveal why IVF embryos are more likely to develop into twins. Researchers believe the laboratory culture could be the cause” https://web.archive.org/web/20070921094734/http://www.eshre.com/emc.asp?pageId=939

New scientist magazine: The stranger within. https://www.newscientist.com/article/mg18024215-100-the-stranger-within/

Strangers within: Meet the other humans who live in your body https://www.newscientist.com/article/mg22930550-400-strangers-within-meet-the-other-humans-who-live-in-your-body/

‘Semi-identical’ twins discovered: Hermaphrodite reveals previously unknown type of twinning. http://www.nature.com/news/2007/070326/full/news070326-1.html



Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s