The Science of When Life Begins

by Stephanie Gray:

Have you ever heard someone who supports abortion claim, “No one knows when life begins”?  The funny thing is, these very individuals actually do claim to know when it begins.  If they ban abortion at 3 months, then they are implicitly saying life begins at 3 months.  If they ban abortion at 6 months, then they are implicitly saying life begins at 6 months.  The question is this: Is where they draw the line based on fact or convenience?

BabyEmbryoMoreover, abortion advocates are making an even greater concession than they realize.  Consider the labels “3 months” or “6 months”: these reveal the passage of time, and show that time is being “clocked” from a beginning point 3 or 6 months prior.  So wherever abortion advocates draw a line, they are unwittingly making this major admission: that life began where they started clocking the passage of time that brought them to 3 or 6 months.  So what happened 3 or 6 months prior?  Fertilization.  And that’s when life begins.

Life begins at fertilization, but not because I say so; rather, because science says so.  Embryology texts repeatedly echo the fact expressed by Dr. Keith Moore in his medical textbook The Developing Human: Clinically Oriented Embryology: “Human development begins at fertilization.”

Dr. Hymie Gordon, Chairman of the Department of Genetics at the Mayo Clinic, agrees: “By all the criteria of modern molecular biology, life is present from the moment of conception.”

Incidentally, Alan Guttmacher former president of Planned Parenthood even admitted this in 1933: “We of today know that man is born of sexual union; that he starts life as an embryo within the body of the female; and that the embryo is formed from the fusion of two cells the ovum and the sperm….This seems so simple and evident to us that it is difficult to picture a time when it was not part of common knowledge.”

In arguably the best paper written about the beginnings of Life, Dr. Maureen Condic, in her piece When Does Human Life Begin? provides an in-depth scientific explanation to back up the aforementioned quotes.  She writes,

From the moment of sperm-egg fusion [the beginning of fertilization], a human zygote acts as a complete whole with all the parts of the zygote interacting in an orchestrated fashion to generate the structures and relationships required for the zygote to continue developing towards its mature state… The zygote acts immediately and decisively to initiate a program of development that will, if uninterrupted by accident, disease, or external intervention, proceed seamlessly through formation of the definitive body, birth, childhood adolescence, maturity, and aging, ending with death. This coordinated behavior is the very hallmark of an organism.

Mere human cells, in contrast, are composed of human DNA and other human molecules, but they show no global organization beyond that intrinsic to cells in isolation. A human skin cell removed from a mature body and maintained in the laboratory will continue to live and will divide many times to produce a large mass of cells, but it will not re-establish the whole organism from which it was removed; it will not regenerate an entire human body in culture. Although embryogenesis begins with a single-cell zygote, the complex, integrated process of embryogenesis is the activity of an organism, not the activity of a cell.

In light of that, two simple questions to ask, as proposed by pro-life apologist Steve Wagner, are these:

  1. If something is growing, isn’t it alive?
  2. If it has human parents, isn’t it human offspring?

And we humans have human rights, don’t we?  Our society says “yes”—that’s why we are outraged when genocides occur.  As for the second point, as long as we don’t re-open the debate about the humanness of women, and as long as we don’t open a debate about the humanness of men, there is no reason to doubt the humanness of their offspring.

As for the first point, at fertilization, a one-celled embryo grows into two cells, then four cells, then eight and so forth.  Thus, he or she is clearly alive.  That embryonic human may be smaller, less developed and more dependent than the rest of us, but let’s remember that a toddler is also smaller, less developed, and more dependent than us too.

We are labeled when we are certain ages (e.g., “embryo” or “toddler”) and as a result of our age, we may or may not be able to do certain things.  But regardless of which age category we fit into, we’re human beings at all stages of our development.  To allow those of us who are older to kill those who are younger is age discrimination.

As for the claim that embryos don’t “look” human; actually, they look exactly as a human should look at that stage of development.  And that brings to mind an analogy from Richard Stith: consider a Polaroid picture.  Once you click the camera and the card comes out, what initially appears is brown/black smudges.  But within a few minutes the image appears with clarity.   The image is captured in an instant but it does need time to develop.  So it is with each of us—who we are as unique, unrepeatable individuals of great dignity is captured in an instant (fertilization); we just need time to develop.

To conclude, it’s worth considering that when scientists of the reproductive technology industry want to create human life in a lab, they don’t plead ignorance about when life begins.  On the contrary, they know exactly when it begins, for they aim to replicate not an individual at 3 or 6 months’ development, but rather they aim to replicate the moment of fertilization.  They aren’t satisfied with a sperm or egg by themselves, but they are satisfied with a one-celled embryo, showing that we really do know when life begins.


Stephanie Gray is co-founder and executive director of the Canadian Centre for Bio-Ethical Reform:


  1. Whole article is based on the idea that “alive = a life” but then fails to address anything like the amputation or gametes (which are both “alive” but clearly not “a life” refuting the equality of the two). The idea of when does a life begin is simply outside the definition of science as it makes no testable predictions, which is why those referred to in the beginning of the article say, “science doesn’t know” as opposed to “science says XYZ”.

    • KBlaney,
      You are right in saying the article does not address that point. Instead, it is assumed by both, those who say “no one knows when life begins” and those who say “life begins at fertilization,” that by “life” they mean the life of a human being or human organism. Yes, gametes and amputated parts of the body are alive but they are not a complete human organism. Indeed, they are “parts” not “wholes.” What is implied by the point “If it has human parents, isn’t it human offspring” is that it is a complete individual human being. Thus, an human embryo is a living and complete individual human organism.

  2. Movie clips from the best window into the womb DVD ever The Biology of Prenatal Development~
    ~ Embryo Heartbeat in Slowmotion 4 1/2 Weeks Pregnant
    embryo Liver & Heart permanent kidneys appear by 5 wks
    embryo 6 wks the rapidly growing brain

    6week embryo cerebral cortex appears neurons connections synapses rapidly growing brain
    6 wks Primitive brainwaves
    In females, the ovaries are identifiable by 7 weeks.
    By 8 weeks, 75% of embryos exhibit right-hand dominance
    Prenatal Development what a 9 Week Fetus looks like via MRI see lungs, ribs
    Eight weeks marks the end of the embryonic period. 2
    9 week fetus can also grasp an object & what else….

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