animated natural history: why dogs have floppy ears

thanks british library (PD)

Wolves: upright, pointy ears.  Most dogs: floppy ears.
Hares and wild rabbits: Ears up.  Many domesticated rabbits: Soft floppy ears. 
Boars/pigs? Check. Goats/goats? Check.  Cats/Cats? Um - that one doesn't work; they're all up and pointy, wild or no. (Cats: Throwing wrenches in the works since...ever.)
Still, the ear phenomenon is prevalent enough that it sparks curiosity.  And when I ran across this short, entertaining animation on the subject at NPR, I learned the latest research on why those ears (and those shorter muzzles and those spotted coats).  A publication by Charles Darwin is namechecked: "The variation of plants and animals under domestication."  Want to idly flip through some of that?  You can find an introduction and several editions here.