Lesson 2.03 Human Population Growth: Distribution

Demographics

Populations of species have certain qualities or characteristics that can be used to describe the population. These qualities are called demographics.

Age, sex, and income are some of the major characteristics or demographics that are used to describe human populations.

These factors are studied by demographers and are used to make predictions about how human populations in specific geographic areas will grow. The number of individuals and their age and sex distribution within a population as well as economic and cultural factors influence how human populations grow.

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Developed Countries

The standard of living is another major factor in an area's population growth. Developed countries, such as the United States, Germany, England, Japan, and Sweden (to name a few) have a higher standard of living because of technological advancements that lead to a higher quality of life.

Because of technological advancements and overall infrastructure the basic physical and organizational structures and facilities (e.g., buildings, roads, and power supplies) needed for the operation of a society , developed countries are able to increase the carrying capacity of their environment. They are able to:

• effectively and efficiently grow food;
• distribute food across great distances;
• maintain better healthcare systems;
• maintain better educational systems;
• have more stable or slower growth.

• use more natural resources;
• use energy at a faster rate;
• produce more waste;
• have a greater negative impact on the environment.

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Population Pyramids

Demographers look at the demographics characteristics of a population to make predictions for different countries. One common demographic tool is the population pyramid, which uses the age and sex distribution of a population to help predict future population trends growth, decrease, or stable .

Males are typically shown on the left side of the pyramid and females on the right. Females tend to outnumber males in the higher age ranges because women typically have a greater life expectancy. Age, which is usually given in age ranges or age cohorts people treated as a group , is plotted on the Y-axis and the population size, which is usually given as a percentage of the total population, is on the X-axis.

View Population Pyramid of the World based on the 2010 population to see an example of a population pyramid. Notice how the pyramid is organized based on the description above.

Population pyramids for developed countries look different from population pyramids for developing countries.

In developing countries, pyramids tend to have a triangle shape because there are more younger-aged people. The birthrate is high and the life expectancy is low. Therefore, the young age cohorts are larger, and the cohorts decrease in size as you go up in age.

In developed countries, population pyramids tend to have a barrel shape. They have less young people with more people in the mid-age range. The life expectancy in developed countries is longer and the birth rates are lower. As a country transitions to being more developed, you see a shift in the distribution of the number of people in each age range. The population pyramids for these countries transition from a triangle shape to more of a barrel shape.

Countries that have longer life expectancies with less births than deaths begin to have birth rates and death rates that are equal or close to zero. This is often referred to as zero population growth - the maintenance of a population at a constant level by limiting the number of live births to only what is needed to replace the existing population. This means that couples have only enough children to replace them. When this happens, countries start to reach zero population growth. Zero population growth is seen more in developed countries, and as countries develop, they tend to head toward zero population growth.

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