My wife and I have two dogs. Gunner is an 9 year-old Shar-Pei, who no one would accuse of being particularly intelligent. The other, Molly, is a 1.5 year-old Leavitt Bulldog. When my wife and I both leave home, we're in the habit of jamming dog biscuits way up the center of bleached cow bones, then leaving one for each of the dogs to chew. Invariably, Molly has gotten hers out by the time we get home, but Gunner, having worked on it for a while, has given up on his bone, which still has the biscuit in it. As soon as we let her loose, Molly trots over to Gunner's bone, carries it over to the hard deck surface, and drops the bone on its end, which dislodges the biscuit.

I don't know whether that shows Molly is a genius or Gunner is a moron, but Gunner hasn't figured this out in more than eight years, while Molly figured it out within a couple weeks of when we got her at 10 weeks old.