True, age makes it closer to the common ancestor. Although as I said, it's a matter of taste whether to call that ancester PIE, or to reserve that name for som

True, age makes it closer to the common ancestor. Although as I said, it's a matter of taste whether to call that ancester PIE, or to reserve that name for some more recent language. But if it branched off earlier, and developed on its own for longer, then we expect it to have diverged more than other languages that existed around the tail end of its existence. So I think what linguists are saying is that ancient Greek, Persian, Sanskrit etc. are all more similar to each other than any of them is to Hittite. And the same goes for the reconstructions we can do for other Indo-European sub-families.