The way Earths population is spread out is called population distribution. People tend to live in uneven clusters on Earths surface. Demography tries to explain why populations change and why population distribution is uneven.
People usually dont move without a good reason. As long as people can make a living where they are, they usually stay there. That means that regions with large populations tend to keep them.
In the past, most people lived on farms where they grew their own food. Therefore, more people lived in places that had good climates for growing crops. After about 1800, things changed. Railroads and steamships made traveling long distances much easier. People moved to cities to work in factories and offices instead of working on farms.
How do you find out how crowded a place really is? Find out how many people live in an area. Then divide that number by the areas square miles or square kilometers. That will give you the population density. Remember, population distribution tells you the actual number of people in an area. Population density tells you the average number of people in an area.
Some places are more crowded, or have a higher population density than others. For example, Japan has a high population density, while Canada has a low population density.
For thousands of years, the worlds population grew slowly. Food supplies were scarce. People lived without clean water and waste removal. Millions died of diseases. Although the birthrate was high, so was the death rate. The life expectancy, or the average length of peoples lives, was short.
Today, death rates have dropped sharply. In some countries, birthrates have increased. As a result, populations have grown very fast. At the same time, people live longer than ever. Scientific progress caused much of this change.
People in many countries still face big problems. Some nations do not have enough fresh water. In parts of Asia and Africa, the population is growing faster than the food supply.
The way people live can be hurt by population growth. There are shortages of jobs, schools, and housing. Public services like transportation and sanitation are inadequate. Forests are disappearing. This causes still more problems.