> Kids and Kittens are good examples of this behavior at the intelligent end of the spectrum: Given time, they'll find a way to get through any gap. They don't need to be as smart as the adults, the adults just need to turn their back for one minute too many. O:-)

As a parent of kids currently aged ~3 thru 7, I concur. Each age has its own ways, but what's worse, they can also coordinate and get you from an angle you wouldn't thought possible, playing your own beliefs about them against you.