Sociologists study population because it affects social structure, especially in crowded areas. They use this to predict and find special patterns to try and figure out how the people will behave in that certain area. The three main things they look at that affect population are birth, death, and movement from one area to another. Those processes are measured with fertility, mortality, and migration. The population keeps growing exponentially and it keeps doubling in less and less time. Thomas Robert Malthus, an English minister and economist, had a theory that states population, if left unchecked, will exceed the food supply. This is because population increases exponentially, while the food supply does not. It was predicted that we will run out of food one day if our population kept growing the way it was. However, were not able to predict the advance in agricultural productivity and birth control.