The Facts of Science Prove That Each Human Life Begins at Fertilization

Agresti, J. D. (2021, December 2). The Facts of Science Prove That Each Human Life Begins at Fertilization. Retrieved from
Agresti, James D. “The Facts of Science Prove That Each Human Life Begins at Fertilization.” Just Facts. 2 December 2021. Web. 20 May 2024.<>.
Chicago (for footnotes)
James D. Agresti, “The Facts of Science Prove That Each Human Life Begins at Fertilization.” Just Facts. December 2, 2021.
Chicago (for bibliographies)
Agresti, James D. “The Facts of Science Prove That Each Human Life Begins at Fertilization.” Just Facts. December 2, 2021.

By James D. Agresti
December 2, 2021

On Wednesday December 1, 2021, the U.S. Supreme Court heard oral arguments in Dobbs v. Jackson. This case involves a Mississippi law that limits abortion to 15 “weeks’ gestation except in medical emergency and in cases of severe fetal abnormality.”

During the hearing, Mississippi Solicitor General Scott G. Stewart defended the law by asserting that the State of Mississippi has an interest in preventing “the purposeful termination of a human life,” but Supreme Court Justice Sonia Sotomayor challenged him and declared:

How is your interest anything but a religious view? The issue of when life begins has been hotly debated by philosophers since the beginning of time. It’s still debated in religions. So, when you say this is the only right that takes away from the state the ability to protect a life, that’s a religious view.

Contrary to Sotomayor and regardless of what any philosopher or religious leader may think, the facts of science are clear that each human life begins at fertilization. As documented below, these facts are from credible science publications that don’t argue for or against abortion. In other words, they are not polemics from people with science degrees but facts from neutral scientific authorities.

The American Heritage Dictionary of Science—which was written by nine highly credentialed scientists under a “precise editorial review” to maintain “a standard of excellence”—defines “life” as:

the form of existence that organisms like animals and plants have and that inorganic objects or organic dead bodies lack; animate existence, characterized by growth, reproduction, metabolism, and response to stimuli.

Those four defining characteristics of life are all present during or soon after fertilization, which occurs when a sperm and egg unite to form a zygote, or the earliest stage of a human embryo:

  1. Growth: Per the textbook Essentials of Human Development: A Life-Span View, “Fertilization begins the period of the zygote,” and “the zygote grows rapidly through cell division.”
  2. Reproduction: Per a paper in the Biochemical Journal, “Sexual reproduction in mammals results in the formation of a zygote, a single cell which contains all the necessary information to produce an entire organism comprised of billions of cells grouped into multitudinous cell types.”
  3. Metabolism: Per the medical text Human Gametes and Preimplantation Embryos: Assessment and Diagnosis, “At the zygote stage,” the human embryo metabolizes “carboxylic acids pyruvate and lactate as its preferred energy substrates.”
  4. Response to stimuli: The Oxford Dictionary of Biochemistry and Molecular Biology defines a “stimulus” as “any event or phenomenon, such as radiation, electrical potential, or addition of molecules that leads to excitation of a tissue or cell.” Experiments have found that human zygotes respond to such stimulants. For example, a paper in the journal Human Reproduction Update documents that a compound called platelet-activating factor “acts upon the zygote” by stimulating “metabolism,” “cell-cycle progression,” and “viability.”

Nor is a zygote just a form of human life like a skin cell. It is an actual human life. As explained in Van Nostrand’s Scientific Encyclopedia, “At the moment the sperm cell of the human male meets the ovum of the female and the union results in a fertilized ovum (zygote), a new life has begun.”

In keeping with the facts above, clinical literature is explicit that each new human life begins at fertilization:

Although controversial from a political perspective, the scientific facts of embryology, genetics, and molecular biology leave no doubt as to when each human life begins—fertilization.

  • December 2, 2021 at 6:11 PM

    Even if one assumes “life” begins at fertilization, what gives anyone the right to require that anyone else sacrifice their lives or welfare for anyone else? This is more of a legal question than a moral one. Would you make an exception for rape or incest? How about the “life of the mother”? What right do you or anyone else have to draw the line?

    • December 3, 2021 at 10:14 AM

      “what gives anyone the right to require that anyone else sacrifice their lives or welfare for anyone else?” It’s not just “anyone else.” It’s a life she helped create through her own actions. Using your logic, a parent would have the right to kill a child if their financial situation becomes dire, or they’re just had an overly stressful day at work. Here’s a better question: What gives someone the right to take the life of another for their own comfort or convenience?

      Rape and incest account for far less than 1% of all abortions. If the mother doesn’t wish to keep the child, the baby can be put up for adoption. In the case of “life of the mother” (which also accounts for, at most, a low single-digit percentage of all abortions), the child can be delivered or a c-section performed, to allow the child a fighting chance at survival in almost all circumstances.

      “What right do you or anyone else have to draw the line?”

      Follow the science only applies when it (allegedly) supports your argument. What’s you position on the jabs?

      • January 14, 2022 at 3:17 PM

        Thank you. Well stated.

    • December 3, 2021 at 11:08 PM

      “How about the “life of the mother”?”
      Self defense is allowed any time your life is in danger.

    • December 7, 2021 at 2:32 PM

      You said, “This is more of a legal question than a moral one.”

      If you think about it, all laws are someone’s morality codified into law. So to say it is not a “moral issue” is not correct. Further it is easy to see that it is a moral issue. I’m sure you would agree that it is morally wrong to take take an innocent human life. Most people would agree with that. There is no doubt that an unborn child human. They are the offspring of two humans. What else could they be but human? Their DNA tells the whole story. And what could be more innocent than an unborn child? They certainly haven’t committed any crime worthy of the death penalty. They haven’t had a trial of their piers, a defense lawyer, countless appeals, or even been charged with a crime. No one even read them their rights.

      I encourage you to reconsider your position and take a minute to look at this issue from the child’s point of view.

  • December 3, 2021 at 8:37 AM

    Nonsense. Science doesn’t define when life begins. It defines the process. Remember “Which came first, the chicken or the egg?” Legally, the issue is to define a point at which life begins.

    • December 3, 2021 at 1:28 PM

      As the article documents, science clearly defines when “each human life begins.” Whether the chicken or egg came first is a pointless distraction from the issue at hand.

  • December 3, 2021 at 9:17 AM

    The fact that is a Supreme Court justice is not intelligent enough to understand how it could be a scientific view rather than a “religious” one is scary.

  • December 3, 2021 at 9:55 AM

    Agreed… Using the most extreme cases don’t make the point, but lets compromise. I hate the thought of killing unborn children. But I will compromise and agree that, “Life of Mother” and Incest/Rape would be exemptions. So think of all the babies saved. But we all know that isn’t what this is about… This is about the right to kill babies for convivence. So why make an argument for extreme cases when the baby killing businesses and advocates have no intention to stop there…

  • December 3, 2021 at 12:01 PM

    I always knew Sotomayor was a Leftist menace. Never realized she was that ignorant

  • December 3, 2021 at 5:12 PM

    Per the Bible. Genesis 2.7 GOD breathed the breath of life into Adam and this is meant to mean putting the SOUL in to Him. Which would mean a baby without taking a breath would not have a soul. The reason I feel you are not a living being until you take your first breath as you will not be alive if you do not breath. Even though they can keep a heart beating and other life function alive you are DEAD your SOUL has left your body.
    I would like to hear commits

    • December 3, 2021 at 6:21 PM

      The Bible says that God created the first humans in a different manner than all others and instructed them to “be fruitful and increase in number,” or in other words, procreate (Genesis 1:28). When one deeply understands the facts of science and the Bible, they always agree, and often in remarkable ways. The issue of when each new human life begins is just such a case, as evidenced by the facts in the article above about the humanity of the unborn and these passages from the Bible:

        • Jeremiah 1:4-5: “The word of the Lord came to me, saying, ‘Before I formed you in the womb I knew you’….”
        • Psalms 22:10: “From my mother’s womb you have been my God.”
        • Psalms 139:13-14: “For you created my inmost being; you knit me together in my mother’s womb.”
        • Luke 1:15: “He [John the Baptist] will be filled with the Holy Spirit even before he is born.”
    • December 3, 2021 at 11:07 PM

      What do you think that God breathing life into Adam means that if a baby has not taken a breath that is is not alive. A fetus or baby is the beginning of life. You are referring to someone’s end of life where they are kept alive by artificial means. Being in a mother’s womb is not an artificial means.

    • December 8, 2021 at 1:25 AM


      I think you are confusing a figure of speech with actual breathing. When God created Adam out of the dust of the ground, he was not alive at first. He was just a body. When God “breathed” into Adam’s nostrils, God gave Adam life. The emphasis in the Scriptures is not that Adam’s “breathing” brought him to life but rather that God gave Adam life.

      Then later, God removed a rib from Adam and also created Eve. This is described in verse 22 of the same chapter… “The LORD God fashioned into a woman the rib which He had taken from the man, and brought her to the man.” There is no mention in this verse or any other verses around it about God breathing live into Eve. Obviously God made Eve alive as well, because He brought her to Adam and gave her to him. How God did it is not mentioned. If the Scriptures were trying to make the point that we must all breathe before we have a soul, it would make sense that it would be mentioned of Eve as well. There is also no other place in all of Scripture that even hints at your conclusion.

      Adam and Eve are unique from all other humans that have ever lived. Neither of them were born, but both were directly created by God. The rest of us were all created by the process of reproduction. This process is evident throughout all of creation. Life begets life. I received life from my parents, just like you did. The same is true for all plants, animals, fish, insects, bacteria, etc. on the planet. The Bible expresses this concept by using the phrase “kind after their kind” passing on life from one generation to another. This is often described as the “seed” of a woman or the “seed” of a man. There are also “seeds” of plants that pass on life to future generations of plants.

      You said that you don’t believe that an unborn child is not alive because it has not taken a breath. Of course the child is alive. From the moment of conception, the child is alive. We know this because from the moment of conception, the child is growing. Dead things don’t grow. Do you know any dead thing that grows?? Another reason we know the child is alive is because the doctor must kill the child BEFORE removing them from the womb. If the child were not alive, there would be no reason to kill him or her.

      Based on all these things, your argument from Genesis 2:7 doesn’t hold up to scrutiny and must be rejected as grasping at straws.

  • January 17, 2022 at 1:13 PM

    In 1933, Alan Guttmacher wrote the following: “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 single cells, the ovum and the sperm. This all seems so simple and evident that it is difficult to picture a time when it wasn’t part of the common knowledge.” [‘Life in the Making”] In 1970, Doctor Malcolm Watts wrote, “The result has been a curious avoidance of the scientific fact, which everyone really knows, that human life begins at conception and is continuous whether intra- or extra-uterine until death. The very considerable semantic gymnastics which are required to rationalize abortion as anything but taking a human life would be ludicrous if they were not often put forth under socially impeccable auspices.” Doctor Watts is no “anti-choice” advocate. And more recently, embryologists Keith L. Moore and T.V.N. Persaud wrote, “Human development begins at fertilization when a sperm fuses with an oocyte to form a single cell, the zygote. This highly specialized, totipotent cell marks the beginning of each of us as a unique individual. The zygote, just visible to the unaided eye, contains chromosomes and genes that are derived from the mother and father. The zygote divides many times and becomes progressively transformed into a multicellular human being through cell division, migration, growth, and differentiation.”
    I Asked Thousands of Biologists When Life Begins. The Answer Wasn’t Popular


Make a Comment

Your email address will not be published. Required fields are marked *

Articles by Topic