The term population refers to the total number of people living in an area at a particular point in time. However, just knowing the population of an area is not very useful. We need ways to relate the population to the land on which these people live.
One way of relating the population to the land is population density. It gives a rough idea of how densely or sparsely populated an area is. This is done by dividing the total population by the area of the land these people occupy. Population density is expressed as the number of people per square kilometer, eg 300 per square kilometer (300 per sq km).
Geographica is a country with an area of 500 square kilometers. The population of this country is 30,000. What is the population density of Geographica?
Population density = total population/total area (it is important to state the formula)
= 30,000 people/500 square kilometers
= 60 people per square kilometer or 60 per sq km
This answer is just an average. It does not mean that there are exactly 60 people in every square kilometer of the country. Indeed, some parts of Geographica may be very densely populated while other areas may be uninhabited.
Another way of relating the population to the land which the people occupy is population distribution. This term refers to the way in which people are spread out over an area. For example, in some islands, most people live near the coast and few live in the interior. There are several factors which affect population distribution including the following:
Steep slopes are generally less densely populated than gently sloping or flat areas. The photo below shows a section of the town of Soufriere in St. Lucia. Notice that most of the buildings are located in the flatter areas. There are very few buildings in the steeper areas.
Drainage and soils:
Infertile or poorly drained soils are usually less densely populated than well drained or fertile areas. Throughout much of history, the Nile delta in the north of Africa has been more densely populated than the surrounding area. The fertility of the soil in the area has allowed it to support a very large population.
Parts of the world where the climate is very harsh are generally less densely populated than areas with a favourable climate. For instance, Antarctica is so cold and inhospitable, that nobody lives there. The people who go there are usually scientists who want to conduct research there.
The Atacama desert is another example of a place with a very harsh climate. Parts of this desert have not experienced any rainfall for over 400 years. No people, or even animals live in these parts. Generally, people prefer to live in areas where water is readily available and the temperature is not extremely high or low.
Areas which have large deposits of minerals such as bauxite tend to have high population densities. In Jamaica for instance there are relatively high population densities near some bauxite mining areas. Some relatively large settlements such as May Pen and Mandeville are located near bauxite mining areas.
At the beginning of the 1900’s, the world’s population was roughly 1.65 billion people. By 1950, the world’s population had grown to about 2.56 billion. In 2000, the world’s population reached 6 billion. The population of the world expected to reach 8 billion in November 2022. The world’s population is growing quite quickly. However, in some countries, the population is decreasing while in others, the population is increasing. Some other countries have a stable population. What are the factors which affect population growth in various countries? Let us examine a few of them:
The fertility rate:
This is the number of children that the average woman will bear in her lifetime. If the fertility rate is about 2.0, then the population tends to be stable. The population will tend to increase in countries which have a fertility rate which is greater than 2.0. In countries which have a fertility rate which is less than 2.0, the population will tend to decrease. The fertility rate has decreased in many countries because the women in those countries are delaying child bearing to pursue higher education and careers.
The birth rate:
This is given as the number of births per thousand. Therefore a birth rate of 20 per thousand means that 20 babies were born for every thousand people in the population. The birth rate is not to be confused with the fertility rate. In countries with a very high birth rate, the population will tend to increase. The population will tend to decrease in countries where the birth rate is very low.
This is given as the number of deaths per thousand. A high death rate may cause the population to grow very slowly or even to decrease. Note that the difference between the birth rate and death rate is known as natural increase.
This is the number of years that someone born today can expect to live. A high life expectancy tends to have a positive effect on population growth. In countries with very low life expectancy, the population tends to grow very slowly or even decrease.
This refers to the proportion of children who die before the age of one. A high infant mortality rate tends to slow the rate of population growth.
This refers to the number of people entering and leaving a country. Large numbers of immigrants will tend to cause an increase in the population. Large numbers of emigrants will reduce the rate of population growth or even cause a decrease in the population.
The Population Pyramid
A population pyramid is a diagram which shows the age and sex structure of a population. It consists of two back to back bar graphs. Males are usually shown on the left and females are usually shown on the right. For both sexes, each age group is represented by a horizontal bar. Population pyramids are considered to be one of the most effective means of graphically showing the age and sex distribution of a population.
At a glance, a population pyramid can tell us a lot. Click on the link below to see different population pyramids. The one on the left has a very wide base and indicates that the population is growing rapidly. It also shows that the population is made up mostly of young people. The one in the middle represents slow growth. Notice that the base of this pyramid is much smaller than the first. The one on the right indicates negative growth which means the population is decreasing. Notice how small the base is relative to the middle of the pyramid. It also shows that the population has a large proportion of older people.
Click the link below to see the population pyramid for Haiti. Would you say that Haiti’s population is growing rapidly, growing slowly or decreasing?