Burgers' Zoo in the Netherlands re-ran a famous chimp study several years ago. A banana was suspended above the chimp enclosure, out of reach to the chimps. The enclosure contains everything the chimps need to get the banana, as long as they use it in the correct order. One female took up the challenge, collecting boxes together to stack up on each other, but it just doesn't quite work. By finding a stick - the final piece in the puzzle - she can finally achieve her goal to reach the banana. This is insight: understanding a problem and finding solutions that aren't obvious. It's a feature shared by both human and chimp minds.