I have translated the urdu text beneath the pictures for those who don't understand the language.
After this event, whenever a monkey tried to climb that ladder driven by the desire to eat bananas, the monkeys standing below did not allow him to climb.
After a while, despite the lure of bananas, no monkey had the courage to climb that ladder.
The scientists decided to replace one of the monkeys. The first thing the new monkey did was to climb the ladder but immediately the other monkeys began to beat him. After many beatings the new monkey decided that he would not climb the ladder even though he didn't know why.