Cat fur

If I were the type of person who thought about these things, I might take the observation that my cats' fur seems to change over time a little more seriously. My cats are getting older, and it seems that their fur is sticking around longer (they're now more DMH's than DSH's). How long does cat fur stick around before it's shed, anyway? A year? Seven years (eyelash fur)? And is there some weird enzyme that the skin produces after a while that makes the fur longer as the bones get thinner (and the cat hunts less since it's no longer "hungry" all the time)? (My cats are *always* hungry. Even when they've just eaten.) If I had the background, I might try to figure this out. As it is, I'll just wonder. And watch the near&dear's bald spot grow.