But consider this new twist. After many centuries in a Moon or Mars colony, they returned to Earth. The humans alive on the Earth at that time would all share their mitochondrial DNA with an earlier common ancestor. Thus the title of Mitochondrial Eve depends very critically on the present human population of the Earth. As people die or are born, the title can change hands.
Further deaths can, however, transfer the title to a more recent woman.
This is part of the reason why I said that each and every word of that definition was important. As an exercise, try to eliminate just one phrase of the definition of the ME and see what happens. The key terms are most-recent , common ancestor , humans alive today , matrilineal descent . So the YcA would not leave the same kind of trace in women living today as the ME did. While the existence of the ME and the YcA are mathematical, I am more interested in the point in time when the titles were conferred on the particular ME and YcA were are talking about today.