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  • Population means the number of people in a geographic area. It can also be used for subgroups of people or animals.
  • Population is also the number or body of inhabitants in a place belonging to a specific social, cultural, socioeconomic, ethnic, or racial subgroup.

This unit describes how the world’s population has grown over the centuries, where people live , the problems that countries have and the dangers of overpopulation. The world population clock shows the many aspects of the world’s current population.

In demographics, the world population is the total number of humans currently living, and was estimated to have reached 7.6 billion people as of May 2018.

Our population is expected to grow to 10 billion by the end of this century but the capacity of our environment to provide space, produce food, and supply energy are limited.

The largest countries in the word in terms of population are China and India, with both now having populations of well over a billion. The United States comes in third with just under 325 million residents. The BRIC countries (Brazil, Russia, India and China), generally regarded as the four major emerging economies expected to dominate in the 21st century, are all in the top ten most populous countries, indicating how important the sheer size of their populations are to their economic expansion.

However, a number of countries considered by the International Monetary Fund to be developing countries (that is, having not achieved a high degree of industrialization relative to their populations, and where the population typically has a medium to low standard of living) also have sizeable populations, including Nigeria (over 190 million), Bangladesh (almost 165 million) and Mexico (around 129 million), demonstrating that the issues affecting developing nations span multiple continents.

It is notable that a number of the largest economies in the world have smaller populations, particularly in Europe. The United Kingdom, Germany, France, and Italy are all among the top ten largest economies and all have populations of under 100 million. Their numbers range from 82 million (Germany) to just under 60 million (Italy).

Furthermore, several extremely small countries, such as Monaco, Luxembourg, and the Cayman Islands – all with fewer than a million residents – play a much larger role in the financial world than their population numbers would suggest. In contrast, Canada, also a major economic player and one of the largest countries in the world by land mass, has a relatively small population for its size, with around 36.5 million residents.

As of 2017, the global population has reached more than 7.5 billion people, spanning the inhabited continents of Africa, North and South America, Asia, Europe and Australia/Oceania. Encompassing the two most highly populated countries in the world – China and India – Asia is by far the largest of the continents, with a total population of over 4.5 billion people.

Basic Population Concepts

Overpopulation, Under Population, Optimum Population

1. Overpopulation

  • Overpopulation is an undesirable condition where there are too many people and not enough resources to support a satisfactory quality of life.
  • Overpopulation is the state whereby the human population rises to an extent exceeding the carrying capacity of the ecological setting.

Overpopulation thus contributes to some of the most compelling environmental problems which encompass:

  • Depletion of Natural Resources

As human population keeps on enlarging, exhaustible natural resources such as arable land, coral reefs, fresh water, fossil fuels, and wilderness forests continue to drop sharply. This creates competitive demands on the vital life-sustaining resources and contributes to an incredible decline in the quality of life.

  • Accelerated Habitat Loss

The increased loss of the ecosystems including wetlands, wildlife, rainforests, coral reefs, aquatic life forms, and grasslands are highly influenced by overpopulation. It is out of overpopulation that activities such as excessive agriculture, environmental pollution, and extensive land development have become more and more intensive.

  • Amplified Climate Change and Global Warming

Because of overpopulation, it means more and more population. The more the number of people, the more the number of vehicles and industries as well as air travels. Furthermore, more population translates to increased use of energy sources such as coal and firewood which contributes to increased greenhouse gas emissions.

Hence, because of the accumulation of human-generated greenhouse gasses and carbon footprint in the atmosphere, the planet has continued to witness amplified global warming and climate change. The effects of climate change and global warming are profound resulting in extreme hunger, drought, flooding, and habitat loss to an extent of threatening the survival of human civilization.

  • Loss of Biodiversity

Overpopulation has seen continued encroachment into frontier forests, heightened pollution, and destruction of natural ecosystems that has greatly contributed to the mass extinction of species. The number of threatened species persists to multiply worldwide whereas some have completely gone extinct.

This is because of the human activities such as acidifying water systems, over-exploitation of natural resources, pollution, over-fishing, poaching, and the deliberate as well as the indirect destruction of natural systems necessary for the survival of different species. These human activities simply alter the natural process combined, thus, destroying the natural ecosystems supporting biodiversity.

  • Depreciation of Fresh Water

The unrelenting nature of overpopulation on earth has destroyed most of the world’s freshwater systems. Most of the lakes, streams, rivers and groundwater making up fresh water have been made unreachable or become too polluted.

  • Lower Life Expectancy and Diminished Quality of Life

Overpopulation lowers the standards of living since it creates stress on the vital resources for survival and increases the difficulty of accessing the consistent supply of quality food, water, energy, health, security and shelter. Consequently, it makes the poor to become poorer, and they often opt for poor living conditions to survive.

Eventually, it gives rise to lower life expectancy. The situation is serious in developing nations such as southern Asia and sub-Saharan Africa where most of the poor populations submit to inadequate and poor diets.

  • Intensive Farming Practices

In regions where populations are high, people resort to farming practices that can produce more food products with cheaper inputs and without encroaching into surrounding lands due to the recent environmental protection policies. Intensive farming has thus resulted, and it has led to soil fertility depletion, re-emergence of parasites, the emergence of new parasites, loss of ecosystems, pollution of water systems, and decreased biodiversity.

  • Rise in Unemployment, Crime Rate, and Violence

In overpopulated nations, the available jobs are fewer than the overall job seeking population. This contributes to high levels of unemployment. In turn, lack of unemployment leads to elevated crime rates because of theft, drug cartels, and militia groups which are exploited as options for attaining basic resources and necessities such as food, good living standards, and wealth. Violence and conflicts arise when people start competing for the available limited resources.


The following are possible causes of overpopulation:

  • Better Medical Facilities

Illnesses that had claimed thousands of lives till now were cured because of the invention of vaccines. People now live longer because of better medical facilities available to them.

  • Migration

People move to better environments where best facilities are available in terms of, education, security, medicals, and employment.

  • Lack of Family Planning

Most developing nations have a large number of people who are illiterate, and have little or no knowledge of family planning. Thereby, getting their children married at an early age and increasing their chances of producing more kids.

  • Technological Advancement in Fertility Treatment

With latest technological advancement and more discoveries in medical science, it has become possible for couple who are unable to conceive to undergo fertility treatment methods and have their own babies. Today there are effective medicines which can increases the chance of conception and lead to rise in birth rate. Moreover, due to modern techniques pregnancies today are far more safer.


After considering the causes and effects of overpopulation, let us look at some possible solutions to reduce them.

  • Better Education

Educating the masses helps them understand the need to have two or three children at the most. Also, by educating the people, they learn about various safe sex techniques and contraceptives methods available to avoid unwanted pregnancy.

  • Family Planning Awareness

Raising awareness among people regarding family planning is very important. Letting them know about serious after effects of overpopulation can help control the rate of population growth.

  • Knowledge of Sex Education

Communicating sex education to young kids at the elementary level is key. By doing so, they learn the right way and not from their peers or through the internet.

In conclusion, Africa’s population is increasing and it’s not showing any signs of slowing down. The only probable solution is to encourage a culture of learning and good education.


2. Under Population

Under population is a situation whereby the size of the population is small in relation to available resources of the country. It is situation where the size of the population is below the equilibrium.

Causes of under population

  • An increase in Death Rate

Natural Catastrophes such as earthquakes, flood etc. will lead to an increase in death rate therefore the country witnesses a reduction

  • A fall in Birth Rate

When a country decides to reduce the number of children for fear of eventual overpopulation or any socio-political factor which does not favor children, the country becomes under-populated

  • High Level of Emigration

A persistent increase in emigration over immigration will leads to a reduction in a country population.

  • Famine

Famine is the scarcity of food caused due to factors like crop failure and disproportionate population. Being a ‘push’ factor, it has an adverse effect on the population of a region or country.

  • War and conflicts

People have waged wars since the middle ages and continue to do so. Advanced technology has made modern warfare a huge factor or element in the decline of population. Individuals fighting over resources and space end up killing each other on a massive scale due to the introduction of nuclear and chemical warfare which has a negative effect on the overall population of an area or region.

  • Disease

Disease and illness has always caused a decline in the population. The emergence of new diseases like HIV/AIDS which has decreased the population globally.


Positive effects of under population

  • No Congestion

A country with less population experiences little or no congestion

  • Employment Opportunities

As a result of small size of the population, there will be enough job opportunity for the people

  • Increased in Social and Infrastructural Facilities

An under Populated Country experiences a higher per capita in terms of social and infrastructural facilities available to the people in the country.

  • Availability of Idle Resources

The fact that a country is less populated means that the resource available in that country is higher than the number of people; hence, many idle resources would abound everywhere.

  • Decrease in pollution and environmental problems

The pressure on natural resources and the basic infrastructure of an area decreases. Levels of pollution are cut down too.


Negative Effects of under population

  • Lower Standard of Living

Under Population engender lower standard of living as a result of inadequate labor force that would have conveniently boost output and production of goods and services

  • Lack of Adequate Manpower

Under population results to shortage of labor with that attendant effect of low investments and income

  • Under utilization of Resources

Resources are highly underutilized in a country with low population

  • Lack of People to Defend the Country

At times of war and emergency, a country might find it difficult to mobilize enough people to defend it

  • Equilibrium at Less than Full Employment

Under population leads to reaching of equilibrium at less than full employment as a result of idle resources.

  • Population ageing

Due to decreased rates of procreation, there is an increase in the social and economic pressure on the youth who have to expand the per capita output in order to support the economy. This also leads to a poor quality of life for the youth.

  • Unstable Economy

Under – population has an adverse effect on the economy causing deflation (decrease in the overall price levels of goods and services). A decline in the population leads to lack of demand.


3. Optimum Population

  • The population is such that it can maximize the benefits from the resources available. It is only when we have optimum population that the quality of life is maximized.
  • Optimum population has been defined as that size of population enabling per capita output of the maximum orders accompanied by the highest possible standards of living under a given set of economic and technological conditions.
  • Optimum population is defined as the ideal population in any country where there is a proper balance between population and available resources whereby the existing factors of production and technology will generate the greatest national product. The concept of optimum population clears the doubt on the issues of overpopulation and under population; it is a concept that strikes the balance between population of a country and its available resources to it.

Benefits of Optimum Population

  1. Effective management: A country with optimum population can be managed easily and effectively, as this is possible through optimal utilization of resources.
  2. Participation in Resources Development: Optimum Population creates participation in resources development of the country.
  3. Higher Standard of Living: It brings about the highest standard of living because the resources available in the country are optimally utilized.
  4. Balance between Population Size and Resources: The relationship between population size and the available resources is not under strain because there is a balance between the two.
  5. Stability in the Economy: The economic is stable because there is full employment and equitable distribution of resources.
  6. Maximum Returns Per Head: Optimum population yields maximum returns per head because people would be fully employed and adequately compensated and remunerated. This motivates them to put in their best.
  7. Resources Dependency: There is effective utilization of the available resources to achieve maximum utility in the economy and the internal dynamics that would have created dependency is properly placed.

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