While some distinguish between human beings and human persons, and therefore contend that a human being does not necessarily possess human rights, I think all would agree that membership in the human species is a necessary, if not sufficient, criteria for human personhood. Accordingly, it is still necessary to answer the following question: at what point during pregnancy, if at all, is a human being created?
I believe that a human being is created at fertilization. This is not a matter of personal opinion, but a biological fact. It follows from the common biological understanding of sexual reproduction that human development begins when the haploid sperm and egg combine to form the diploid zygote. The point at which human development begins is the point at which a new human being is created.
There is substantial evidence from standard embryological texts to support this claim:
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.
Human development begins at fertilization, the process during which a male gamete or sperm (spermatozoon development) 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).
Keith L. Moore, The Developing Human: Clinically Oriented Embryology, 7th edition. Philadelphia, PA: Saunders, 2003. pp. 16, 2
Although life is a continuous process, fertilization (which, incidentally, is not a 'moment') 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.
Ronan O'Rahilly and Fabiola Müller, Human Embryology and Teratology, 3rd edition. New York: Wiley-Liss, 2001. p. 8.
It is the penetration of the ovum by a spermatozoan and resultant mingling of the nuclear material each brings to the union that constitues the culmination of the process of fertilization and marks the initiation of the life of a new individual.
Clark Edward Corliss, Patten's Human Embryology: Elements of Clinical Development. New York: McGraw Hill, 1976. p. 30.
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.
Jan Langman, Medical Embryology, 3rd edition. Baltimore: Williams and Wilkins, 1975. p. 3.
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.
E.L. Potter and J.M. Craig, Pathology of the Fetus and the Infant, 3rd edition. Chicago: Year Book Medical Publishers, 1975. p. vii.
The term conception refers to the union of the male and female pronuclear elements of procreation from which a new living being develops. The zygote thus formed represents the beginning of a new life.
J.P. Greenhill and E.A. Friedman, Biological Principles and Modern Practice of Obstetrics. Philadelphia: W.B. Saunders, 1974. pp. 17, 23.
Many other popular scientific and reference works also make this claim:
Biologically speaking, human development begins at fertilization.
The Biology of Prenatal Develpment, National Geographic, 2006. [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.
In the Womb, National Geographic, 2005. [Video]
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.
Douglas Considine (ed.), Van Nostrand's Scientific Encyclopedia, 5th edition. New York: Van Nostrand Reinhold Company, 1976. p. 943.
In fusing together, the male and female gametes produce a fertilized single cell, the zygote, whch is the start of a new individual.
Time Magazine and Rand McNally, Atlas of the Body. New York: Rand-McNally, 1980. pp. 139, 144.
A new individual is created when the elements of a potent sperm merge with those of a fertile ovum, or egg.
"Pregnancy," The New Encyclopedia Britannica, 15th ed. Macropedia, Vol. 14 (Chicago: Encyclo. Brit., 1974) 968.
A number of prominent scientists and physicians have also made this claim:
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.
Professor Micheline Matthews-Roth, Harvard University Medical School
I have learned from my earliest medical education that human life begins at the time of conception.
Dr. Alfred M. Bongioanni, Professor of Pediatrics and Obstetrics, University of Pennsylvania
After fertilization has taken place a new human being has come into being. [It] is no longer a matter of taste or opinion...it is plain experimental evidence. Each individual has a very neat beginning, at conception.
Dr. Jerome LeJeune, Professor of Genetics, University of Descartes
By all the criteria of modern molecular biology, life is present from the moment of conception.
Professor Hymie Gordon, Mayo Clinic
The beginning of a single human life is from a biological point of view a simple and straightforward matter – the beginning is conception.
Dr. Watson A. Bowes, University of Colorado Medical School
The basic fact is simple: Life begins not at birth, but conception.
Ashley Montague, Geneticist and Professor at Harvard University and Rutgers University
An official U.S. Senate report on the question of when life begins reached the following 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.
Report, Subcommittee on Separation of Powers to Senate Judiciary Committee S-158, 97th Congress, 1st Session 1981, 7.
What does NSG think?
