Ever since Darwin, the concept of teleology has been suspect among biologists. What is so controversial about teleology? Most likely, its history! From the earliest Greek philosophers on, it was widely believed that the world must have a purpose because, as Aristotle would put it, “nature does nothing in vain,” and neither does God, as a Jew or Christian would say. In this often misunderstood view, any change in this world is due to final causes that move things to an ultimate goal, a predetermined end. All things would achieve certain ends or goals because they were designed that way by nature or by God; that’s how hormones, for instance, are supposed to reach their target cells.