What about a hierarchy of humanity? The just fertilized egg is less than a zygote; the zygote is less than second trimester; second less than third, third less than born, baby less than adult?
Before you all jump on me, realize we do have a hierarchy of rights: the testimony of a child has no weight in western courts without corroboration(sp?), you cannot drive or sign a contract until you are at least 15, and in most cases 16, you cannot enlist or vote until at least 18; nor can you run for public office until you reach the age of majority.
Try to get a mortgage or rent a car before you are twenty-five.
Try to get a vasectomy or tubal ligation before thirty.
As a society, we understand that there are things most of us do not understand or cannot understand until we are of a certain age: therefore we already agree in diminishing humanity as we get younger.
Running away after opening the can of worms. . .
Pangloss