one way of looking at population change is with a type of graph called a population pyramid. It is called a pyramid because that used to be the most common shape. We can see this shape with Japan's population in 1950 in Chart A. The population was largely young then, and it was the end of an era when most people lived in the countryside. In these rural areas, children often worked together with their parents and helped to produce the food, goods, and household product that the family needed. There were many diseases without cures and these often killed children, so families were large to increase the change that some children would live to become adults.