Humanae Vitae

If you're anything like me, you've probably been in a situation where someone has asked you about the scientific status of nascent human life. Is it human? As I am not familiar with any specific biology textbooks, I'm usually not able to provide a satisfactory answer. This morning on First Things, I find something to help:

The leading works of human embryology corroborate this. The chapter on human development in Keith L. Moore and T.V.N. Persaud’s The Developing Human begins with this sentence: “Human development begins at fertilization when a male gamete or sperm (spermatozoon) unites with a female gamete or oocyte (ovum) to form a single cell—a zygote. This highly specialized, totipotent cell marked the beginning of each of us as a unique individual.” Or their definition of embryo: “The developing human during its early stages of development.” And consider their definition of the term zygote: “This cell results from the union of an oocyte and a sperm during fertilization. A zygote is the beginning of a new human being (i.e., an embryo)” (emphasis added).

The piece this is taken from can be found here.