An orangutan, highly educated, has two books in his cage. One is a Bible, the other is Darwin's Origin of Species. He's still trying to find out if he's his brother's keeper or his keeper's brother.
i'll explain it----in the bible in genesis theres adam and eve and they hav 2 sons called cain and abel, and cain takes abel out into a field one day and murders him. later god asks cain where abel is and cain ses 'how should i know, am i my brothers keeper?'and that means 'should i know where my brother is at all times and watch evry little move he makes and be responsible wen he gets hurt?' thats wat the brothers keeper is refrence to. the keepers brother comment means is the zoo keeper ment to be his brother because according to darwin we evolved from monkeys (or apes if u prefer) its a play on words