But you don't have to take my word for it. Here is an article with 41 quotes from scientific sources that show this scientific consensus on the topic. And if you don't believe these, you're welcome to speak to any biologist or embryologist or read any human anatomy or embryology text for yourself. Even better, you could study these subjects, get a degree and become an expert on the topic. No matter how deep you decide to dig, you'll come to the same conclusion. It's not difficult at all to determine when life begins. It's already been done. It's been verified many, many times. It's a simple fact that life begins at fertilization.
Here are some of the quotes from the article:
“Fertilization is the process by which male and female haploid gametes (sperm and egg) unite to produce a genetically distinct individual.”Signorelli et al., Kinases, phosphatases and proteases during sperm capacitation, CELL TISSUE RES. 349(3):765 (Mar. 20, 2012).
“Human life 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.
“It is the penetration of the ovum by a sperm and the resulting mingling of nuclear material each brings to the union that constitutes the initiation of the life of a new individual.”Clark Edward and Corliss Patten’s Human Embryology, McGraw – Hill Inc., 30.
“The zygote is human life….there is one fact that no one can deny; Human beings begin at conception.”Landrum B. Shettles, “Rites of Life: The Scientific Evidence for Life Before Birth” Grand Rapids, MI: Zondervan, 1983 p 40. (Landrum Shettles was the first scientist to successfully complete an in vitro fertilization.)
“[All] organisms, however large and complex they might be as full grown, begin life as a single cell. This is true for the human being, for instance, who begins life as a fertilized ovum.”Dr. Morris Krieger “The Human Reproductive System” p 88 (1969) Sterling Pub. Co.
“The first cell of a new and unique human life begins existence at the moment of conception (fertilization) when one living sperm from the father joins with one living ovum from the mother. It is in this manner that human life passes from one generation to another. Given the appropriate environment and genetic composition, the single cell subsequently gives rise to trillions of specialized and integrated cells that compose the structures and functions of each individual human body. Every human being alive today and, as far as is known scientifically, every human being that ever existed, began his or her unique existence in this manner, i.e., as one cell. If this first cell or any subsequent configuration of cells perishes, the individual dies, ceasing to exist in matter as a living being. There are no known exceptions to this rule in the field of human biology.”James Bopp, ed., Human Life and Health Care Ethics, vol. 2 (Frederick, MD: University Publications of America, 1985).
“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.”Clark, J. ed., The Nervous System: Circuits of Communication in the Human Body, Torstar Books Inc., Toronto, 1985, page 99.
These are just a few of the many, many such quotes from scientists and medical professionals that affirm that fertilization marks the beginning of a new human life. This is well-known fact that no biologist contests.
The ONLY reason remaining for doubting this obvious fact is that people don't like it. They don't want to believe it. Why? Perhaps they don't want to have to face the fact that abortion kills a human individual. If they can stick their heads in the sand and pretend they don't know when life begins, they can keep their position that abortion is okay. I can't think of any other reason.