Primates in zoos are mostly insane.
That's the lesson I take from Carnivorous gorillas | The Economist. It wasn't the point of the essay, but it's hard to escape the conclusion that they're not having much fun.
In a similar vein our local zoo has run through several psychotic Polar bears. They seem "ok" when they start out, but they show increasingly abnormal repetitive behaviors. They're going to get a much more impressive residence soon, so maybe the next batch will be merely neurotic.
Smart animals, shockingly, don't do well in confinement under continuous observations by history's most terrible large predator.
Let's not mention dolphins.