Almost anyone with a high school education can correctly answer the question “When does human life begin?” by responding “at conception” or at “fertilization” of a human egg by a sperm cell. While we may not understand, or only vaguely recall, the precise process by which an egg and sperm combine to create a new unique human being, this basic truth about human life falls into the category of things we can’t not know.

Yet today, many educated people who do know better assert that human life begins at some later stage of development.

They arbitrarily push forward the starting point to implantation or viability, or even birth and beyond, to accommodate their approval of abortifacient drugs and devices, in vitro fertilization (IVF) procedures, lethal embryo research (including embryonic stem-cell research), chemical and surgical abortion, and eugenic infanticide.

Because such confusion arises more from muddled values than a misunderstanding of basic science, one might think that the white paper “When Does Human Life Begin?: A Scientific Perspective” would have limited usefulness. To the contrary, the Westchester Institute for Ethics and the Human Person in Thornwood, N.Y., has done a great service to the public debate and to policymakers by publishing such a paper, authored by Maureen Condic, associate professor of neurobiology and anatomy at the University of Utah School of Medicine.

Based on her objective review of current scientific evidence in human embryology, Condic convincingly demonstrates that a new human organism (an embryo that is called a “zygote” in its one-celled form) comes into being at the moment when the sperm and egg fuse. This occurs mere seconds after the sperm has penetrated the thin layer of protein enveloping the egg.

Her evidence refutes the recent assertions of some scientists that a human life begins at the eight-cell stage when gene transcription begins, or four days post-fertilization when the inner cell mass forms distinct from placental cells, or at 5 to 6 days when the embryo implants in the uterine wall. Condic demonstrates that each of these events — like a baby’s first tooth or the onset of puberty — are simply milestones along life’s path and “not indicative of any fundamental change in the entity.”

And her proof also counters the claim of some scientists (reflected in many textbooks and even legal codes) that a human organism begins to exist only at “syngamy,” an event that occurs roughly 24 hours after the sperm enters the egg.

Recall that every cell has a nucleus where the cell’s DNA is located. A thin membrane separates the nucleus from the rest of the cell (cytoplasm). In a new human embryo, however, there are briefly two nuclei — one with dad’s DNA and one with mom’s. Before the first cell division takes place, the DNA from mom and dad (23 chromosomes each) have to match up and copy themselves.

To do that, the membranes surrounding their nuclei need to break down. That event is called syngamy.

Condic shows how the zygote is already behaving like an organism before syngamy because factors from the sperm and egg are “interact[ing] coordinately to orchestrate subsequent development.” The zygote already possesses DNA different from his or her mother and father and is “carry[ing] on the activities of life” with “organs that are separate … but mutually dependent.”

For example, within minutes after the sperm enters the cytoplasm of the egg, the new zygote sends out chemical signals that change the outer protein layer to prevent other sperm from entering the zygote.

Within 30 minutes of the sperm entering the egg, factors contributed by the sperm signal the nucleus of the egg to reduce its two sets of DNA to one. Within the first hour, proteins contributed by the sperm interact with chemicals in the zygote to create changes that will allow the zygote to begin dividing and growing. The nuclei are already being directed to line up across from each other for the first cell division.

Also, as Condic notes, the breakdown of the membranes separating the nuclei from the sperm and egg “is not a unique, ‘zygote-forming’ event, but rather it is part of every round of cell division that occurs through life.”

In this summary form I’ve just given, it may be difficult to follow the complex interplay of paternal and maternal factors within the newly formed zygote. Fortunately, Condic takes pains to walk us through these first essential “baby steps” of every new human life. The white paper also contains illustrations and a very helpful glossary to aid in understanding these intricate processes.

Writing as a scientist, Condic criticizes analogies comparing the development of human embryos to manufactured products, even when the embryos’ lives begin in a laboratory. Conceptualizing human procreation as a manufacturing process encourages erroneous thinking that the human being does not fully exist until viability or birth, when all the steps of the manufacturing process presumably are completed — in the case of a car, when it is fully assembled and ready to leave the factory.

But cars, unlike people, are built externally by others acting on them, building and assembling components. In contrast, she explains, the defining feature of the human zygote is that it has the power “both to generate all the cells of the body and simultaneously to organize those cells into coherent, interacting bodily structures.” Thus, from the first moment of fusion between sperm and egg, everything necessary to develop the adult human being is present, provided the new human embryo is allowed to develop in a safe environment and is able to access nutrition.

“When Does Human Life Begin” comes at a critical time. The new administration and many members of the next Congress are already championing policies that will put nascent human lives at even greater risk than they are today.

Federal funding and a vast expansion of human embryonic stem-cell research is almost a foregone conclusion. Our next president strongly supports such funding, and he can reverse the Bush moratorium with an executive order.

The president-elect also has cosponsored legislation to greatly increase government funding of contraception, including abortifacients, and mandate contraceptive coverage in health insurance policies.

Annually, over 100,000 children are born in the United States as a result of assisted reproductive technologies. Most people are unaware that in the process of making these children, hundreds of thousands of sibling-embryos die or are killed.

In addition, President-elect Obama has promised Planned Parenthood that his “first act” as president will be to sign the Freedom of Choice Act (FOCA), a law that will effectively wipe out 35 years’ of pro-life laws at the state and federal levels. Many of these laws have been shown to reduce abortions and, in their absence, we can expect abortion rates to increase.

Many Americans are weary of political battles and deeply concerned about the economy and other issues that touch their families. But we cannot turn a blind eye to the legalized killing that’s occurring in our country on an unprecedented scale. What lofty ideal does America still represent when its foundational principle — the inherent, God-given right to life of every human being — is violated by the very institutions entrusted with caring for the lives of vulnerable people: the family, the medical profession and the state?

We must urgently convey to our fellow citizens the inherent value and dignity of every human being. From the first moment of conception to one’s natural death, every human being, regardless of size, age, sex, race, mental or physical ability, is a unique and irreplaceable creature, made in God’s image and infinitely loved by God. Every life is, therefore, worthy of protection and concern. There are no exceptions. Laws that tolerate exceptions are unjust and must be opposed.

Condic and the Westchester Institute are to be applauded for rigorously defining the beginning point of each human life from the perspective of science. The white paper should prove to be an excellent tool in our pro-life arsenal to refute claims that entities destroyed by abortifacients, destructive embryo research, IVF procedures, and abortions are something less than fully human beings.

Susan Wills is assistant director

for education and outreach in

the U.S. bishops’ Secretariat

of Pro-Life Activities.