Answer:
As new people are born and so on, the population of the world changes greatly. Colder places usually have less people whilst in hot places, there are a lot of people. LEDC's (less economically developed countries) generally have more babies because they are less educated. MEDC's (more economically developed countries) have less. In LEDC's people also have more children because it makes you higher than everyone else and you have more people to work and earn money.