““Human development begins at fertilization when a sperm fuses with an oocyte to form a single cell, the zygote. All major external and internal structures are established during the fourth to eighth weeks.”
“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.