When chimps collide

"Five chimpanzees were placed in a cage. In the cage was a set of stairs; and above the stairs a bunch of bananas hanging by a rope. After a while one of the chimps started up the stairs to get the bananas. As he did this all the chimps in the cage were blasted with cold water and ran to a corner. A little while later another of the chimps went up the stairs for the bananas. Once more all the chimps were drenched with cold water. Later, another chimp started up the stairs but on seeing this the other four chimps attacked him. The next day one of the five was taken out and replaced with a new chimp. The new chimp saw the bananas and started up the stairs but was attacked by the others. On the third day another of the original five chimps was taken from the cage and replaced by a new one. He too tried to reach the bananas but was immediately attacked by the other four - even the one that'd been attacked himself the day before. This went on until none of the original five chimps were left. By now none of them had ever been sprayed with water, but they'd still attack any chimp that tried to climb the stairs. Why? Because for them that's the way it had always been."