The Bible does not explicitly state a precise moment when human life begins. That omission has led theologians, religious scholars, and laymen to put forth a variety of interpretations and opinions. Some say that life begins at conception, citing Psalm 139:13-16 as evidence, where the Psalmist speaks of being formed in the womb by God. Others argue that life begins at birth, when a newborn takes its first breath, citing the creation account in Genesis 2:7 where God breathed the breath of life into Adam. Still others maintain that life begins at some unspecified point between conception and birth, citing Exodus 21:22-25, in which accidental injury to a pregnant woman that endangers the life of her fetus is addressed. Those examples and other life-defining passages in Scripture have resulted in conflicting opinions among Bible believers on exactly when human life begins.
From a scientific viewpoint there is also diversity of opinion among researchers, but in general life is defined by biologists applying criteria that distinguish living organisms from non-living matter. The specifics may vary based on context, but below are some of the key criteria commonly used to determine if an organism is alive:
Cellular Organization: Living organisms are composed of one or more cells, which are the basic structural and functional units of life. Cells carry out various metabolic processes necessary for life.
Metabolism: Living organisms exhibit metabolism, defined as chemical reactions that occur within cells to maintain life. Those reactions typically involve the conversion of nutrients into energy and the synthesis of molecules needed for growth and repair.
Homeostasis: Living organisms maintain internal stability and balance through homeostasis, which involves regulating factors such as temperature, pH, and nutrient levels within a defined range.
Response to Stimuli: Living organisms respond to stimuli coming from their environment, such as light, temperature, touch, and chemical signals. Those responses may be behavioral, physiological, or biochemical in nature.
Reproduction: Living organisms have a capacity to reproduce, either sexually or asexually, to produce offspring that inherit genetic traits from their parents.
Adaptation:Living organisms can adapt to changes in their environment over time through evolutionary processes, such as natural selection, mutation, and genetic variation.
Many Christians are surprised to discover that the scientific definition of life, as outlined above, essentially mirrors the perspective on life advocated by the “pro-life” movement, except for the parts about asexual reproduction and evolution. That political movement asserts that life commences at conception, when a sperm fertilizes an egg, forming a zygote with unique DNA. It is argued that the zygote possesses all the genetic material necessary for human development, thus warranting consideration as a human being with inherent rights, including the right to life. That argument serves as the foundation for the movement’s opposition to abortion, as it views abortion as the deliberate termination of human life.
In the discussion that follows in the remainder of this article, it should be noted that there is no attempt being made to pinpoint an exact moment when human life begins. Instead, the focus is solely on what the Bible says about identifying when life is present in an organism, as opposed to determining a precise moment when an organism first acquires life.
As Bible believers, we are blessed to have a criterion revealed by God and recorded in the sacred text to guide us in determining the presence of life in an organism. That singular criterion is found in Leviticus 17:11(a), which says “the life of the flesh is in the blood.” That verse tells us how we are to understand the presence of life from the viewpoint of God as defined in Scripture. It provides a definitive statement about the relationship between life, flesh, and blood that supersedes all man-made opinions and definitions about life, stating without ambiguity that when flesh contains its own blood, it is to be considered to have life in the eyes of God. Conversely, if flesh lacks its own blood, then it is not considered to be alive by God.
What implication does that definition of life in Leviticus, which requires the presence of blood for flesh to have life, have on the various secular interpretations claiming to determine when human life begins? To answer that question, one must consider the latest research findings from the fields of Embryology and Developmental Biology that investigate the sequential stages of human development in the womb, with special attention given to development of the blood system from zygote through embryonic stage to early fetal stages.
In human development, the embryo starts to develop its own circulatory system early in gestation, but in a progressive process that takes many weeks. Early in the third week after conception, the embryo forms three primary germ layers: the endoderm, the mesoderm, and the ectoderm. The mesoderm layer, which develops into various bodily structures including the cardiovascular system, undergoes differentiation to form blood vessels and blood cells. By the end of the third week and into the fourth week, the embryo’s circulatory system starts to take form. That process involves the development of a primitive heart and blood vessels, and the beginning of blood cell production in the yolk sac. The embryo’s developing circulatory system will begin to interface with the mother’s blood system through the placenta, which facilitates nutrient and gas exchange.
Around the fifth week of gestation, the embryo’s rudimentary circulatory system begins to become more distinct and independent. The early heart-cell tubes come together and start to pulse, forming a basic pumping mechanism. Circulation begins as that proto-heart starts to send blood cells through developing vessels. Additionally, the liver and spleen begin to contribute to blood cell production, taking over from the yolk sac. By the end of the embryonic period, around the seventh to eighth week of gestation, the major components of the circulatory system are established. The heart is almost fully formed, and blood vessels are well developed, including the major arteries and veins. At this stage, the embryo has become a fetus with its own functioning circulatory system, although it continues to rely on the placenta for oxygen and nutrient exchange until birth. There are minor differences among medical researchers about exactly when the stages of human development outlined above occur during pregnancy, and no doubt timing can vary a bit from woman to woman.
All researchers agree that no blood is present in the single-cell zygote that results at the moment of conception. Thus, using God’s definition for flesh having life as dictated by Leviticus 17:11(a), it can be stated with absolute certainty that life does not begin at the moment of conception, at least in the eyes of God. And furthermore, based on the absence of a fully-functioning circulatory system pumping blood through its flesh, an embryo probably does not meet the biblical definition for the presence of life, either. However, once an embryo becomes a fetus with a heart pumping its own blood through the arteries and veins of its flesh, which all researchers agree will have happened by the end of the seventh or eighth week of pregnancy, and certainly no later than the end of the first trimester, it can be said without equivocation that the fetus is a living human being created in the image of God, and thus deserving of the unalienable rights derived from having that unique status
This article is an excerpt from Searching for the Serpent (available for download in PDF format on this website) that discusses ways in which many Christians have added interpretation to the clear meaning of Scripture.