When does human life begin? Many people say that this is a philosophical or religious question. Christians maintain that life begins at conception. Does this mean that the question of when life begins is purely religious? In reality, scientists agree on when human life begins.
Let's look at some sources.
The Developing Human: Clinically Oriented Embryology, 6th ed. Keith L. Moore, Ph.D. & T.V.N. Persaud, Md., (Philadelphia: W.B. Saunders Company, 1998), 2-18:
"[The Zygote] results from the union of an oocyte and a sperm. A zygote is the beginning of a new human being. Human development begins at fertilization, the process during which a male gamete or sperm ... unites with a female gamete or oocyte ... to form a single cell called a zygote. This highly specialized, totipotent cell marks the beginning of each of us as a unique individual."
From Human Embryology & Teratology, Ronan R. O'Rahilly, Fabiola Muller, (New York: Wiley-Liss, 1996), 5-55:
Essentials of Human Embryology, William J. Larsen, (New York: Churchill Livingstone, 1998), 1-17:
"In this text, we begin our description of the developing human with the formation and differentiation of the male and female sex cells or gametes, which will unite at fertilization to initiate the embryonic development of a new individual. ... Fertilization takes place in the oviduct ... resulting in the formation of a zygote containing a single diploid nucleus. Embryonic development is considered to begin at this point... This moment of zygote formation may be taken as the beginning or zero time point of embryonic development."
Human Embryology, 3rd ed. Bradley M. Patten, (New York: McGraw Hill, 1968), 43:
Keith L. Moore, The Developing Human: Clinically Oriented Embryology, 7th edition. Philadelphia, PA: Saunders, 2003. pp. 16, 2:
(updated, still the same)
"Human begins at fertilization, the process during which a male gamete or sperm (spermatozoo developmentn) unites with a female gamete or oocyte (ovum) to form a single cell called a zygote. This highly specialized, totipotent cell marked the beginning of each of us as a unique individual." "A zygote is the beginning of a new human being (i.e., an embryo)."
T.W. Sadler, Langman's Medical Embryology, 10th edition. Philadelphia, PA: Lippincott Williams & Wilkins, 2006. p. 11:
"Development begins with fertilization, the process by which the male gamete, the sperm, and the femal gamete, the oocyte, unite to give rise to a zygote."
Keith L. Moore, Before We Are Born: Essentials of Embryology, 7th edition. Philadelphia, PA: Saunders, 2008. p. 2:
"[The zygote], formed by the union of an oocyte and a sperm, is the beginning of a new human being."
J.P. Greenhill and E.A. Friedman Biological Principles and Modern Practice of Obstetrics (Philadelphia: W.B. Sanders, 1974), 17:
"The zygote thus formed represents the beginning of a new life."
Ronan O'Rahilly and Fabiola Miller, Human Embryology and Teratology, 3rd edition. New York: Wiley-Liss, 2001. p. 8:
"Although life is a continuous process, fertilization... is a critical landmark because, under ordinary circumstances, a new genetically distinct human organism is formed when the chromosomes of the male and female pronuclei blend in the oocyte."
William J. Larsen, Essentials of Human Embryology. New York: Churchill Livingstone, 1998. pp. 1, 14:
"Human embryos begin development following the fusion of definitive male and female gametes during fertilization... This moment of zygote formation may be taken as the beginning or zero time point of embryonic development."
Langman, Jan. Medical Embryology. 3rd edition. Baltimore: Williams and Wilkins, 1975, p. 3:
"The development of a human being begins with fertilization, a process by which two highly specialized cells, the spermatozoon from the male and the oocyte from the female, unite to give rise to a new organism, the zygote."
E.L. Potter and J.M. Craig Pathology of the Fetus and the Infant, 3d ed. (Chicago: Year Book Medical Publishers, 1975), vii:
"Every time a sperm cell and ovum unite a new being is created which is alive and will continue to live unless its death is brought about by some specific condition."
Kaluger, G., and Kaluger, M., Human Development: The Span of Life, page 28-29, The C.V. Mosby Co., St. Louis, 1974:
"In that fraction of a second when the chromosomes form pairs, the sex of the new child will be determined, hereditary characteristics received from each parent will be set, and a new life will have begun."
Lennart Nilsson A Child is Born: Completely Revised Edition (Dell Publishing Co.: New York) 1986:
"...but the whole story does not begin with delivery. The baby has existed for months before - at first signaling its presence only with small outer signs, later on as a somewhat foreign little being which has been growing and gradually affecting the lives of those close by..."
Considine, Douglas (ed.). Van Nostrand's Scientific Encyclopedia. 5th edition. New York: Van Nostrand Reinhold Company, 1976, p. 943:
"Embryo: The developing individual between the union of the germ cells and the completion of the organs which characterize its body when it becomes a separate organism.... 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.... The term embryo covers the several stages of early development from conception to the ninth or tenth week of life."
Carlson, Bruce M. Patten's Foundations of Embryology. 6th edition. New York: McGraw-Hill, 1996, p. 3:
"Almost all higher animals start their lives from a single cell, the fertilized ovum (zygote)... The time of fertilization represents the starting point in the life history, or ontogeny, of the individual."
Turner, J.S., and Helms, D.B., Lifespan Developmental, 2nd ed., CBS College Publishing (Holt, Rhinehart, Winston), 1983, page 53:
"A zygote (a single fertilized egg cell) represents the onset of pregnancy and the genesis of new life."
Clark, J. ed., The Nervous System: Circuits of Communication in the Human Body, Torstar Books Inc., Toronto, 1985, page 99:
"Each human begins life as a combination of two cells, a female ovum and a much smaller male sperm. This tiny unit, no bigger than a period on this page, contains all the information needed to enable it to grow into the complex ...structure of the human body. The mother has only to provide nutrition and protection."
Scarr, S., Weinberg, R.A., and Levine A., Understanding Development, Harcourt Brace Jovanovich, Inc., 1986. page 86:
"The development of a new human being begins when a male's sperm pierces the cell membrane of a female's ovum, or egg....The villi become the placenta, which will nourish the developing infant for the next eight and a half months."
Thibodeau, G.A., and Anthony, C.P., Structure and Function of the Body, 8th edition, St. Louis: Times Mirror/Mosby College Publishers, St. Louis, 1988. pages 409-419:
"The science of the development of the individual before birth is called embryology. It is the story of miracles, describing the means by which a single microscopic cell is transformed into a complex human being. Genetically the zygote is complete. It represents a new single celled individual."
DeCoursey, R.M., The Human Organism, 4th edition McGraw Hill Inc., Toronto, 1974. page 584:
"The zygote therefore contains a new arrangement of genes on the chromosomes never before duplicated in any other individual. The offspring destined to develop from the fertilized ovum will have a genetic constitution different from anyone else in the world."
In the Womb, National Geographic, 2005 (Prenatal Development Video):
"The two cells gradually and gracefully become one. This is the moment of conception, when an individual's unique set of DNA is created, a human signature that never existed before and will never be repeated."
The Biology of Prenatal Development, National Geographic, 2006. (Video):
"Biologically speaking, human development begins at fertilization."
Encyclopedia Britannica, "Pregnancy," page 968, 15th Edition. Chicago 1974:
"A new individual is created when the elements of a potent sperm merge with those of a fertile ovum, or egg."
Leslie Brainerd Arey, "Developmental Anatomy" seventh edition (Philadelphia: Saunders, 1974), 55:
"The formation, maturation and meeting of a male and female sex cell are all preliminary to their actual union into a combined cell, or zygote, which definitely marks the beginning of a new individual. The penetration of the ovum by the spermatozoon, and the coming together and pooling of their respective nuclei, constitutes the process of fertilization."
From California Medicine 113, no.3 (1970), reprinted in The Human Life Review 1, no.1 (1975): 103-4:
"...since the old ethic has not been fully displaced it has been necessary to separate the idea of abortion from the idea of killing, which continues to be socially abhorrent. 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. It is suggested that this schizophrenic sort of subterfuge is necessary because while a new ethic is being accepted the old one has not yet been rejected."
"...each of us has a unique beginning, the moment of conception...As soon as the twenty-three chromosomes carried by the sperm encounter the twenty-three chromosomes carried by the ovum, the whole information necessary and sufficient to spell out all the characteristics of the new being is gathered...(W)hen this information carried by the sperm and by the ovum has encountered each other, then a new human being is defined which has never occurred before and will never occur again...[the zygote, and the cells produced in the succeeding divisions] is not just simply a non-descript cell, or a "population" or loose "collection" of cells, but a very specialized individual, i.e., someone who will build himself according to his own rule." (As quoted in Linacre Quarterly, February, 1993)
In 1981 (April 23-24) a Senate Judiciary Subcommittee held hearings on the very question before us here: When does human life begin? Appearing to speak on behalf of the scientific community was a group of internationally-known geneticists and biologists who had the same story to tell, namely, that human life begins at conception - and they told their story with a complete absence of opposing testimony. (Subcommittee on Separation of Powers to Senate Judiciary Committee S-158, Report, 97th Congress, 1st Session, 1981):
Dr. Micheline M. Mathews-Roth, Harvard medical School, gave confirming testimony, supported by references from over 20 embryology and other medical textbooks that human life began at conception:
"It is incorrect to say that biological data cannot be decisive...It is scientifically correct to say that an individual human life begins at conception."
Dr. Jerome Lejeune, "Father of Modern Genetics", told the lawmakers:
"To accept the fact that after fertilization has taken place a new human has come into being is no longer a matter of taste or opinion...it is plain experimental evidence. Each individual has a very neat beginning, at conception."
Dr. McCarthy de Mere, medical doctor and law professor, University of Tennessee, testified:
"The exact moment of the beginning of personhood and of the human body is at the moment of conception."
Dr. Alfred Bongiovanni, Professor of Pediatrics and Obstetrics, University of Pennsylvania School of Medicine, concluded:
"I am no more prepared to say that these early stages represent an incomplete human being than I would be to say that the child prior to the dramatic effects of puberty ... is not a human being....I have learned from my earliest medical education that human life begins at the time of conception."
Dr. Richard V. Jaynes:
"To say that the beginning of human life cannot be determined scientifically is utterly ridiculous."
Dr. Landrum Shettles, sometimes called the "Father of In Vitro Fertilization" notes:
"Conception confers life and makes that life one of a kind."
And on the Supreme Court ruling Roe v. Wade:
"To deny a truth [about when life begins] should not be made a basis for legalizing abortion."
Professor Eugene Diamond:
"...either the justices were fed a backwoods biology or they were pretending ignorance about a scientific certainty."
Gordon, Hymie, M.D., F.R.C.P., Chairman of Medical Genetics, Mayo Clinic, Rochester:
"By all criteria of modern molecular biology,life is present from the moment of conception...Science has a very simple conception of man; as soon as he has been conceived, a man is a man."
C. Christopher Hook, M.D. Oncologist, Mayo Clinic, Director of Ethics Education, Mayo Graduate School of Medicine:
"When fertilization is complete, a unique genetic human entity exists."
The official Senate report reached this conclusion:
"Physicians, biologists, and other scientists agree that conception marks the beginning of the life of a human being - a being that is alive and is a member of the human species. There is overwhelming agreement on this point in countless medical, biological, and scientific writings."
Dr. Jasper Williams, Former President of the National Medical Association, From Newsweek November 12, 1973 (p 74):
"Human life begins when the ovum is fertilized and the new combined cell mass begins to divide."
D.J. Moran, M.D., J.D. Gorby, M.D., and T.W. Hilgers, M.E., "Abortion in the Supreme Court: Death Becomes a Way of Life.", Sheed and Ward, 1974:
"Individual human life begins at conception and is a progressive, ongoing continuum until natural death. This is a fact so well established that no intellectually honest physician in full command of modern medical knowledge would dare to deny it. There is no authority in medicine or biology who can be cited to refute this concept. It is not a "theory," as Justice Blackmun wished to easily pass it off."
Shettles, Landrum, M.D., Rorvik, David, Rites of Life: The Scientific Evidence for Life Before Birth, page 36, Zondervan Publishing House, Grand Rapids, Michigan, 1983:
"... Conception confers life and makes you one of a kind. Unless you have an identical twin, there is virtually no chance, in the natural course of things, that there will be "another you" - not even if mankind were to persist for billions of years."
Dr. Micheline Matthews-Roth, Harvard Medical School: Quoted by Public Affairs Council:
"....it is scientifically correct to say that human life begins at conception."
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 [human] life has begun."
Norman Ford, "When Did I Begin?" (New York: Cambridge University Press, 1988) 115:
"These pronuclei [of the sperm and oocyte] fuse with each other to produce the single, diploid 2N nucleus of the fertilized zygote. This moment of zygote formation may be taken as the beginning or zero time point of embryonic development."
Dr. Alan Guttmacher, ardent proponent of abortion, in his book Pregnancy and Birth: A Book for Expectant Parents New American Library; Revised Ed edition (January 1, 1962) He was the president of Planned Parenthood and fought to make and keep abortion legal:
"A facet that makes the obstetrician's burden unique in the whole field of medicine is his double obligation; he simultaneously cares for two patients, the mother and the infant...The essential step in the initiation of life is by fertilization, the penetration of the ovum by a spermatozoan and the fusion of the two cells into a single cell."
Planned Parenthood's former medical director Mary Calderone, M.D. Quoted by pro-choice author Magda Denes. Appears in "The Zero People: Essays on Life" by Jeffrey Hensley, Servant Publications (March 1983) p. 9:
"Fertilization, then, has taken place. A baby has been conceived."
"Drama of Life Before Birth" Life Magazine April 1965, cited in "The Facts of Life" Life Messengers:
"The birth of a human life really occurs at the moment the mother's egg cells is fertilized by one of the father's sperm cells."
Prenatal Care, US Department of Health and Human Services, Maternal and Child Health Div 1990:
"Your baby starts out as a fertilized egg...For the first six weeks, the baby is called an embryo."
So as we have seen, the question of when life begins has been answered by science. The question is, will we grant these new individuals the right to live?
AUTHOR'S NOTE: Some of these quotes come from Abort73 and were used with permission. Others I have compiled from various sources.