And exactly why do you believe that gastrulation marks anything beyond another stage of development. You clearly don’t understand the topic and are grasping at wiki straws. Here are some references from medical school textbooks used to teach the subjects of embryology, fetology, developmental biology, and OB/Gyn and highly respected, peer reviewed medical journals. They are quite explicit with regard to when an individual human being’s life begins.
“Often,this morula is inaccurately referred to as a ‘fertilized egg’ because the blastomeres remain inside the female parent’s oocyte outer cell membrane. That is an incorrect characterization, because the 23 -chromosome oocyte no longer exists; all the cells within the morula have the unique genome—46 chromosomes and a complement of mitochondrial DNA —of the newly conceived individual life.” Moore and Persaud, The Developing Human, 6th ed., (p. 43)
“the proposition that an unborn child is a human being from conception is “supported by standard textbooks on embryology or human biology”T.W. SADLER, LANGMAN’S MEDICAL EMBRYOLOGY (John N. Gardner ed., 6th ed.
“Fertilization is an important landmark because, under ordinary circumstances, a new, genetically distinct human being is thereby formed... The zygote is a unicellular human being... Ronan R. O’Rahilly, Fabiola Muller, (New York: Wiley-Liss), 5, 55. EMBRYOLOGY & TERATOLOGY
“Every time a sperm cell and ovum unite a new human 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, 3d ed. (Chicago: Year Book Medical Publishers, vii.
“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.” John C. Fletcher, Mark I. Evans, “Maternal Bonding in Early Fetal Ultrasound Examinations,” New England Journal of Medicine, February 17, 1983.
Now do feel free to provide some equally credible sources that state explicitly that the offspring of two human beings is EVER anything other than a human being.
Does the genetic makeup of the fertilized egg alter at any stage past the immediate point of entry of the sperm, into the egg? Is the genetic arrangement of the fused gametes final, before gastrulation?
Without a unique DNA, you don’t have an individual.