Interesting point. In the process of adopting a pure-bred Slovakian-line GSD, I've learned that German Shepherd Dogs didn't exist at all until the early 1900's,

Interesting point. In the process of adopting a pure-bred Slovakian-line GSD, I've learned that German Shepherd Dogs didn't exist at all until the early 1900's, and the modern Slovakian line (which is related to the DDR line, which is when the two lines became rapidly and visibly diversified when the Iron Curtain divided Germany from the late 40's to the late 80's) is in danger of fading away altogether. And that was only in 40 years -- admittedly with intentional breeding, but it's conceivable that changes in diet, parasites, tumultuous periods of history, seismic changes, or even war/pillaging/violence could rapidly change the makeup of an entire continent within just a few decades. In fact, we've seen that in very recent history.