In in article in one of its printed publications, NARAL asserts that “Personhood at conception is a religious belief, not a provable biological fact.”
The truth is that science is clear and overwhelmingly consistent in affirming that human life begins at conception and fertilization.
Below are 24 scientific sources, most of which are secular and non-biased, that teach that life begins at fertilization/conception.
Human development begins at fertilization, approximately 14 days after the onset of the last menstrual period… 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.
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.
Human development begins at fertilization when an oocyte (ovum) from a female is fertilized by a sperm (spermatozoon) from a male.
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.
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.
The time of fertilization represents the starting point in the life history, or ontogeny, of the individual.
It is the penetration of the ovum by a spermatozoan and the resultant mingling of the nuclear material each brings to the union that constitutes the culmination of the process of fertilization and marks the initiation of the life of a new individual.
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.
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.
Every baby begins life within the tiny globe of the mother's egg... It is beautifully translucent and fragile and it encompasses the vital links in which life is carried from one generation to the next. Within this tiny sphere great events take place. When one of the father's sperm cells, like the ones gathered here around the egg, succeeds in penetrating the egg and becomes united with it, a new life can begin.
Biologically speaking, human development begins at fertilization.
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.
Fertilization is "that wondrous moment that marks the beginning of life for a new unique individual."
In fusing together, the male and female gametes produce a fertilized single cell, the zygote, which is the start of a new individual.
A new individual is created when the elements of a potent sperm merge with those of a fertile ovum, or egg.
In 1981, a United States judiciary subcommittee invited experts to testify on when life beings.
I have learned from my earliest medical education that human life begins at the time of conception... I submit that human life is present throughout this entire sequence from conception to adulthood and that any interruption at any point throughout this time constitutes a termination of human life... I am no more prepared to say that these early stages [of development in the womb] 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. This is human life at every stage.
After fertilization has taken place, a new human being has come into being... [This] is no longer a matter of taste or opinion... [this is] not a metaphysical contention; it is plain experimental evidence... Each individual has a very neat beginning, at conception.
By all the criteria of modern molecular biology, life is present from the moment of 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... Our laws, one function of which is to help preserve the lives of our people, should be based on accurate scientific data.
The beginning of a single human life is from a biological point of view a simple and straightforward matter—the beginning is conception. This straightfoward biological fact should not be distorted to serve sociological, political, or economic goals.
One prominent physician points out the following concerning these senate hearings:
Pro-abortionists, though invited to do so, did not produce even a single export witness who would specifically testify that life begins at any point other than conception or implantation. Only one witness said no one can tell when life begins.
Montague is unsympathetic to the prolife cause, yet affirms the following:
The basic fact of life is simple: life begins not at birth, but conception.
Nathanson was a cofounder of NARAL (the National Abortion Rights Action League). He was the owner and director of the largest abortion clinic in the western hemisphere at the time. His clinic conducted over 60,000 abortions.
However, after continuing to study the science of fetology and using ultrasound to observe unborn children in the womb, Nathanson concluded that he had been very mistaken about his view of abortion. He resigned from his position and wrote in the New England Journal of Medicine that he was deeply troubled by his "increasing certainty that I had in fact presided over 60,000 deaths."
After this, Nathanson produced a film called The Silent Scream, where he says the following:
Modern technologies have convinced us that beyond question the unborn child is simply another human being, another member of the human community, indistinguishable in every way from any of us.
Then, Nathanson wrote Aborting America to teach the public about the truth concerning the abortion rights movement, of which he had been a primary leader.
Nathanson did all of this while he was still an atheist, and his conclusions were not based upon religion, but rather purely upon biological facts.
Shettles was an attending obstetrician gynecologist for 27 years at Columbia-Presbyterian Medical Center in New York. He was a pioneer in sperm biology, fertility, and sterility, and he is internationally famous for discovering male and female-producing sperm. His intrauterine photographs of preborn children appear in over 50 medical textbooks. Dr. Shettles says the following concerning abortion:
I oppose abortion. I do so, first, because I accept what is biologically manifest—that human life commences at the time of conception—and, second, because I believe it is wrong to take innocent human life under any circumstance. My position is scientific, pragmatic, and humanitarian.
This symposium came to the following conclusion:
The changes occuring between implantation, a six-week embryo, a six-month fetus, a one-week-old child, or a mature adult are merely stages of development and maturation. The majority of our group could find no point in time between the union of sperm and egg, or at least the blastocyst stage, and the birth of the infant at which point we could say that this was not a human life.
This report summarized the issue this way:
Physicians, biologists, and other scientists agree that conception marks the beginning of the life of a human being—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.