The new zoo was an exciting place. In keeping with modern views as to how such matters should be handled, substantial sums were spent to provide the best possible environment and mental stimulation for the animals residing there.
It happened one day that a visiting official stopped by the primate area and happened to notice an ape sitting on a rock with an open book in either hand, looking first at one and then at the other. Upon closer examination, he identifies the books: the Bible, and Darwin's "Origin of Species". The ape is clearly vexed.
Curious, he asks a nearby worker,
"What's with the books?"
"Oh, that ape is trying to decide whether he's his brother's keeper ... or his keeper's brother ..."