In case you wondered …

… Respect for Unborn Human Life: The Church's Constant Teaching | USCCB.

• In 1827, with the discovery of the human ovum, the mistaken biology of Aristotle was discredited. Scientists increasingly understood that the union of sperm and egg at conception produces a new living being that is distinct from both mother and father.  Modern genetics demonstrated that this individual is, at the outset, distinctively human, with the inherent and active potential to mature into a human fetus, infant, child and adult.  From 1869 onward the obsolete distinction between the "ensouled" and "unensouled" fetus was permanently removed from canon law on abortion.