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Introduction
The rapid growth of the world's population over the past one hundred years results from a difference between the rate of birth and the rate of death. The human population will increase by 1 billion people in the next decade. This is like adding the whole population of China to the world's population. The growth in human population around the world affects all people through its impact on the economy and environment. The current rate of population growth is now a significant burden to human well-being. Understanding the factors which affect population growth patterns can help us plan for the future.
The purpose of this unit is to examine some important factors about overpopulation. This unit addresses:
(1) The definition of overpopulation (2) the causes of rapid population growth (3) the consequences of rapid population growth, and (4) actions and strategies that can be developed to solve problems caused by overpopulation.
This unit consists of core knowledge about the causes and consequences of overpopulation, lesson plans, teacher resources, student reading list, a list of speakers and a bibliography. Although this unit is intended primarily for students in grades 5-8, teachers in both elementary and high school can use this unit to explore key ideas and concepts about the population explosion.
The environment is our physical surroundings. This includes both human (man-made), social and physical (natural) features. Natural features include soil, the atmosphere, vegetation and wildlife. Human features include housing, transport and industry. Social features include things such as culture, language and political systems.
Geographers are concerned about human action in the environment. Human interference with the environment causes problems such as soil erosion, global warming and acid rain.
You may ask how we as individuals can have an impact on the environment. Our actions can help to increase and decrease the problems highlighted above.
For example turning off lights that are not being used helps to reduce global warming.
THE POPULATION EXPLOSION BY PAUL AND ANNE EHRLICH
Having considered some of the ways that humanity is destroying its inheritance, we can look more closely at the concept of "overpopulation." All too often, overpopulation is thought of simply as crowding: too many people in a given area, too high a population density. For instance, the deputy editor in chief of Forbes magazine pointed out recently, in connection with a plea for more population growth in the United States: "If all the people from China and India lived in the continental U.S. (excluding Alaska), this country would still have a smaller population density than England, Holland, or Belgium." The appropriate response is "So what?" Density is generally irrelevant to questions of overpopulation. For instance, if brute density were the criterion, one would have to conclude that Africa is "under populated," because it has only 55 people per square mile, while Europe (excluding the USSR) has 261 and Japan 857. A more sophisticated measure would take into consideration the amount of Africa not covered by desert or "impenetrable" forest. This more habitable portion is just a little over half the continent's area, giving an effective population density of 117 per square mile. That's still only about a fifth of that in the United Kingdom. Even by 2020, Africa's effective density is projected to grow to only about that of France today (266) and few people would consider France excessively crowded or overpopulated.
When people think of crowded countries, they usually contemplate places like the Netherlands (1,031 per square mile), Taiwan (1,604), or Hong Kong (14,218). Even those don't necessarily signal overpopulation—after all, the Dutch seem to be thriving, and doesn't Hong Kong have a booming economy and fancy hotels? In short, if density were the standard of overpopulation, few nations (and certainly not Earth itself) would be likely to be considered overpopulated in the near future. The error, we repeat, lies in trying to define overpopulation in terms of density; it has long been recognized that density per se means very little.
The key to understanding overpopulation is not population density but the numbers of people in an area relative to its resources and the capacity of the environment to sustain human activities; that is, to the area's carrying capacity. When is an area overpopulated? When its population can't be maintained without rapidly depleting nonrenewable resources (or converting renewable resources into nonrenewable ones) and without degrading the capacity of the environment to support the population. In short, if the long-term carrying capacity of an area is clearly being degraded by its current human occupants, that area is overpopulated.
THE DEFINITION OF OVERPOPULATION
In the past, infant and childhood deaths and short life spans used to limit population growth. In today's world, thanks to improved nutrition, sanitation, and medical care, more babies survive their first few years of life. The combination of a continuing high birth rate and a low death rate is creating a rapid population increase in many countries in Asia, Latin America and Africa and people generally lived longer. Over-population is defined as the condition of having more people than can live on the earth in comfort, happiness and health and still leave the world a fit place for future generations.
1 What some people now believe that the greatest threat to the future comes from overpopulation. It took the entire history of humankind for the population to reach 1 billion around 1810. Just 120 years later, this doubled to 2 billion people (1930); then 4 billion in 1975 (45 years). The number of people in the world has risen from 4.4 billion people in 1980 to 5.8 billion today. And it is estimated that the population could double again to nearly 11 billion in less than 40 years.
2. This means that more people are now being added each day than at any other time in human history. Looking ahead, world population is projected to exceed 6 billion before the year 2000. And according to a report by the United Nation Population fund, total population is likely to reach 10 billion by 2025 and grow to 14 billion by the end of the next century unless birth control use increases dramatically around the world within the next two decades.
3. Both death rates and birth rates have fallen, but death rates have fallen faster than birth rates. There are about 3 births for each death with 1.6 births for each death in more developed countries (MDCs) and 3.3 births for each death in less developed countries (LDCs). The world's population continues to grow by 1 billion people every dozen years.
4. On one hand, some politicians call for countries, especially MDCs to increase their population size to maintain their economic growth and military security. On the other hand, critics denote that one out of five people living here today is not properly supported and believe that the world is already limited in resources.
THE CONSEQUENCES OF RAPID POPULATION GROWTH
Rapid human population growth has a variety of consequences. Population grows fastest in the world's poorest countries. High fertility rates have historically been strongly correlated with poverty and high childhood mortality rates. Falling fertility rates are generally associated with improved standards of living, increased life expectancy, and lowered infant mortality. Overpopulation and poverty have long been associated with increased death, and disease. People tightly packed into unsanitary housing are inordinately vulnerable to natural disasters and health problems.
However, most of the world's 1.2 billion desperately poor people live in less developed countries (LDCs). Poverty exists even in MDCs. One in five Soviet citizens reportedly lives below the country's official poverty line. In the United States, 33 million people - -one in eight Americans are below the official poverty line. The rapid expansion of population size observed since the end of World War II in the world's poorest nations has been a cause of their poverty.
Lessons Plans
This year the ideas that I present for lessons plans will involve several hands-on activities that will promote problem solving and critical thinking skills.
Lesson Plan I
Overview: The purpose of this lesson is to illustrate the concept of population growth rate.
Material Needed: World Population Data Sheet to find the birth and death rates.
Do This: Ask what is the birth rate for the world? And what is the death rate?. Have students find growth rates for two different countries or regions.
Lesson Plan II
Population growth occurs when the birth rate exceeds the death rate. Tell students worldwide, the human birth rate is currently three times the death rate
Concept
This activity demonstrates the relationship between birth and death rate and of population growth within a finite space.
Procedure:
1. Fill a bucket with water and add food coloring so it will be more visible in a clear container. Place the empty, clear container with the towel under it in front of the class.
2. Ask for two volunteers from the class to assist. Designate number 1 for one student and number 2 for the other. Each student should tape the appropriate number tag to the student.
3. Hold up the clear container: This will represent the world, and the colored water in the bucket will represent people. Number 1, will add people to the world by pouring dippers of water into the container. Number 2, will be taking people from the world by scooping water out of the clear container and pouring it back into the bucket. At this time, the world's birth rate is three times the death rate. Based on that fact, who should receive the large dipper? Who should use the small dipper?
Discussion:
1. Why did the water level rise steadily
2. What would this mean if the clear container really was the world?
Source: People and the Planet, Zero Population growth, Inc. Wash., D. C. 1996.
Lesson Plan III
Overview: In a society where tradition often clashes with modern ideology, decision making may be taxing.
Goal: To act out the decision making process of a married couple in an urban area in Connecticut discussing whether or not they will add another child to their family.
Objective: student will (1) discuss attitudes affecting family size in Connecticut; (2) make a decision after listening to opinion.
Skills To Be Developed
1. Role Playing
2. Persuasive speaking
3. Problem Solving
Do This:
Read students a scenario that describes a specific situation involving a decision concerning family size in Connecticut. Choose six students to be the participants in the role playing activity. Select three males and three females and give each student a description of their character. All students who are not role players will pretend that they are the couple who must make the important decision about whether or not to have another child. Poll the students. Did you choose to have another child? Why or why not? What if any particular argument, was the most important in affecting your decision?
[Source: FAO Photo Library]
Primary Health Care
Improvements to urban health services would have significant impact. More comprehensive health coverage, including immunization campaigns, would improve nutrition among the urban poor by preventing gastrointestinal and infectious diseases, promoting adequate diet among pregnant and lactating women and encouraging proper infant and child feeding. However, urban health services often observe an “inverse care law”: those in greatest need of care have the poorest access to it. Few governments have formulated urban health policies giving priority to the poor and, even when such plans and programmes do exist, their implementation is hampered by resource shortages aggravated in recent years by economic recession. A further barrier is the chaotic administration typical of many overcrowded Third World cities.
Agencies agree, therefore, on the need to adapt WHO's Primary Health Care (PHC) approach - until now a mainly rural phenomenon - to the needs of the urban poor. Described as a “renaissance in community health”, PHC is a strategy encompassing total, primary-level health coverage as well as action to attack the fundamental causes of health problems through policies establishing equity in employment, income, education, housing and planning. One increasingly popular instrument for applying this approach in poor urban areas is neighbourhood health programmes, the equivalent district level PHC arrangements promoted by WHO in rural areas. While no established blueprint for such programmes exists, successful neighbourhood schemes have emerged in Cali, Addis Ababa, Djakarta and Manila, usually based on community health centres with a wide deployment of health workers and emphasis on public health education campaigns. Coverage so far has been limited, but the neighbourhood programmes could be expanded and consolidated. Essential to the PHC approach, WHO stresses, is the parallel development of a decentralized network of hospitals supporting the primary system. This reorganization was successful in Cali, where the strengthening of peripheral health units benefited particularly the poor populations of outlying barrios.
Population Distribution
Population distribution means the pattern of where people live. World population distribution is uneven. Places which are sparsely populated contain few people. Places which are densely populated contain many people. Sparsely populated places tend to be difficult places to live. These are usually places with hostile environments e.g. Antarctica. Places which are densely populated are habitable environments e.g. Europe.
Population Density
Population density is a measurement of the number of people in an area. It is an average number. Population density is calculated by dividing the number of people by area. Population density is usually shown as the number of people per square kilometer. The map below is a choropleth (shading) map and illustrates population density. The darker the color the greater the population density.
There are a range of human and natural factors that affect population density. The tables below illustrate this.
Physical Factors High Density Low Density
Relief
(shape and height of land) Low land which is flat e.g. Ganges Valley in India High land that is mountainous e.g. Himalayas
Resources Areas rich in resources (e.g. coal, oil, wood, fishing etc.) tend to densely populated e.g. Western Europe Areas with few resources tend to be sparsely populated e.g. The Sahel
Climate Areas with temperate climates tend to be densely populated as there is enough rain and heat to grow crops e.g. UK Areas with extreme climates of hot and cold tend to be sparsely populated e.g. the Sahara Desert
Population Change
The world's population is growing very rapidly. In 1820 the world's population reached 1 billion. In 1990 it reached 6 billion people.
This rapid growth in population has been called a population explosion.
The major reason for population changes, whether in an individual country or for the whole world, is the change in birth and death rates. The birth rate is the number of live babies born in a year for every 1000 people in the total population. Death rates are number of people dying per 1000 people. When birth rates are higher than death rates the population of an area will increase.
Over the past 150 years improvements in health care and sanitation around the world have led to a drop in the death rate. While birth rates have dropped in MEDCs, birth rates are still high in LEDCs. Therefore the number of people in the world has grown rapidly.
Life Expectancy
Life expectancy is the average age a person can expect to live to in a particular area. Life expectancy can be used as an indicator of the overall 'health' of a country. From this figure you can determine many features of a country e.g. standard of living. As a general rule the higher the life expectancy the healthier (or developed) a country is.
The Demographic Transition Model
The Demographic Transition Model attempts to show how a population change as a country develops.
The model is divided into four stages.
Stage 1
Birth rate and death rate are high - low natural increase - low total population
Stage 2
Birth rate is high - death rate is falling - high natural increase (population growth)
Stage 3 Falling birth rate - low death rate - high natural increase (population growth)
Stage 4
Birth rate and death rate is low - low natural increase - high total population
The Demographic Transition Model does not take into account migration.
Population Structure / Population Pyramids
The population structure for an area shows the number of males and females within different age groups in the population. This information is displayed as an age-sex or population pyramid. Population pyramids of LEDCs (Less Economically Developed Countries) typically have a wide base and a narrow top. This represents a high birth rate and high death rate. Population pyramids of MEDCs (More Economically Developed Countries) typically have a roughly equal distribution of population throughout the age groups. The top obviously gets narrower as a result of deaths. Population pyramids are used to show the structure of the population according to age and sex.
"Earth's present human population is over 6,200 million."
Using the numbers above, we see that human population increased by a factor of 1.84 (just less than doubled) in the60-year period from 1900 to 1960. It doubled (roughly) in the40-year period from 1960 to 2000. In absolute numbers, the picture is more revealing. In the 60-year period from 1900 to 1960, human population increased by 1,389 million. In the
40-year period from 1960 to 2000, it increased by 3,041 million. Consider that recent "doubling in 40 years" for the period 1960 to 2000 (increase of just over 3 billion). This is an average increase of 75 million per year - or
about 205,000 per day, 8,500 per hour, 140 per minute. Now consider the 10-year period from 1990 to 2000.The increase for that period is 796 million. This is an average increase of 79.6 million per year - or about 218, 000 per day, 9,100 per hour, 150 per minute.
The rapid growth of the world's population over the past one hundred years results from a difference between the rate of birth and the rate of death. The human population will increase by 1 billion people in the next decade. This is like adding the whole population of China to the world's population. The growth in human population around the world affects all people through its impact on the economy and environment. The current rate of population growth is now a significant burden to human well-being. Understanding the factors which affect population growth patterns can help us plan for the future.
The purpose of this unit is to examine some important factors about overpopulation. This unit addresses:
(1) The definition of overpopulation (2) the causes of rapid population growth (3) the consequences of rapid population growth, and (4) actions and strategies that can be developed to solve problems caused by overpopulation.
This unit consists of core knowledge about the causes and consequences of overpopulation, lesson plans, teacher resources, student reading list, a list of speakers and a bibliography. Although this unit is intended primarily for students in grades 5-8, teachers in both elementary and high school can use this unit to explore key ideas and concepts about the population explosion.
The environment is our physical surroundings. This includes both human (man-made), social and physical (natural) features. Natural features include soil, the atmosphere, vegetation and wildlife. Human features include housing, transport and industry. Social features include things such as culture, language and political systems.
Geographers are concerned about human action in the environment. Human interference with the environment causes problems such as soil erosion, global warming and acid rain.
You may ask how we as individuals can have an impact on the environment. Our actions can help to increase and decrease the problems highlighted above.
For example turning off lights that are not being used helps to reduce global warming.
THE POPULATION EXPLOSION BY PAUL AND ANNE EHRLICH
Having considered some of the ways that humanity is destroying its inheritance, we can look more closely at the concept of "overpopulation." All too often, overpopulation is thought of simply as crowding: too many people in a given area, too high a population density. For instance, the deputy editor in chief of Forbes magazine pointed out recently, in connection with a plea for more population growth in the United States: "If all the people from China and India lived in the continental U.S. (excluding Alaska), this country would still have a smaller population density than England, Holland, or Belgium." The appropriate response is "So what?" Density is generally irrelevant to questions of overpopulation. For instance, if brute density were the criterion, one would have to conclude that Africa is "under populated," because it has only 55 people per square mile, while Europe (excluding the USSR) has 261 and Japan 857. A more sophisticated measure would take into consideration the amount of Africa not covered by desert or "impenetrable" forest. This more habitable portion is just a little over half the continent's area, giving an effective population density of 117 per square mile. That's still only about a fifth of that in the United Kingdom. Even by 2020, Africa's effective density is projected to grow to only about that of France today (266) and few people would consider France excessively crowded or overpopulated.
When people think of crowded countries, they usually contemplate places like the Netherlands (1,031 per square mile), Taiwan (1,604), or Hong Kong (14,218). Even those don't necessarily signal overpopulation—after all, the Dutch seem to be thriving, and doesn't Hong Kong have a booming economy and fancy hotels? In short, if density were the standard of overpopulation, few nations (and certainly not Earth itself) would be likely to be considered overpopulated in the near future. The error, we repeat, lies in trying to define overpopulation in terms of density; it has long been recognized that density per se means very little.
The key to understanding overpopulation is not population density but the numbers of people in an area relative to its resources and the capacity of the environment to sustain human activities; that is, to the area's carrying capacity. When is an area overpopulated? When its population can't be maintained without rapidly depleting nonrenewable resources (or converting renewable resources into nonrenewable ones) and without degrading the capacity of the environment to support the population. In short, if the long-term carrying capacity of an area is clearly being degraded by its current human occupants, that area is overpopulated.
THE DEFINITION OF OVERPOPULATION
In the past, infant and childhood deaths and short life spans used to limit population growth. In today's world, thanks to improved nutrition, sanitation, and medical care, more babies survive their first few years of life. The combination of a continuing high birth rate and a low death rate is creating a rapid population increase in many countries in Asia, Latin America and Africa and people generally lived longer. Over-population is defined as the condition of having more people than can live on the earth in comfort, happiness and health and still leave the world a fit place for future generations.
1 What some people now believe that the greatest threat to the future comes from overpopulation. It took the entire history of humankind for the population to reach 1 billion around 1810. Just 120 years later, this doubled to 2 billion people (1930); then 4 billion in 1975 (45 years). The number of people in the world has risen from 4.4 billion people in 1980 to 5.8 billion today. And it is estimated that the population could double again to nearly 11 billion in less than 40 years.
2. This means that more people are now being added each day than at any other time in human history. Looking ahead, world population is projected to exceed 6 billion before the year 2000. And according to a report by the United Nation Population fund, total population is likely to reach 10 billion by 2025 and grow to 14 billion by the end of the next century unless birth control use increases dramatically around the world within the next two decades.
3. Both death rates and birth rates have fallen, but death rates have fallen faster than birth rates. There are about 3 births for each death with 1.6 births for each death in more developed countries (MDCs) and 3.3 births for each death in less developed countries (LDCs). The world's population continues to grow by 1 billion people every dozen years.
4. On one hand, some politicians call for countries, especially MDCs to increase their population size to maintain their economic growth and military security. On the other hand, critics denote that one out of five people living here today is not properly supported and believe that the world is already limited in resources.
THE CONSEQUENCES OF RAPID POPULATION GROWTH
Rapid human population growth has a variety of consequences. Population grows fastest in the world's poorest countries. High fertility rates have historically been strongly correlated with poverty and high childhood mortality rates. Falling fertility rates are generally associated with improved standards of living, increased life expectancy, and lowered infant mortality. Overpopulation and poverty have long been associated with increased death, and disease. People tightly packed into unsanitary housing are inordinately vulnerable to natural disasters and health problems.
However, most of the world's 1.2 billion desperately poor people live in less developed countries (LDCs). Poverty exists even in MDCs. One in five Soviet citizens reportedly lives below the country's official poverty line. In the United States, 33 million people - -one in eight Americans are below the official poverty line. The rapid expansion of population size observed since the end of World War II in the world's poorest nations has been a cause of their poverty.
Lessons Plans
This year the ideas that I present for lessons plans will involve several hands-on activities that will promote problem solving and critical thinking skills.
Lesson Plan I
Overview: The purpose of this lesson is to illustrate the concept of population growth rate.
Material Needed: World Population Data Sheet to find the birth and death rates.
Do This: Ask what is the birth rate for the world? And what is the death rate?. Have students find growth rates for two different countries or regions.
Lesson Plan II
Population growth occurs when the birth rate exceeds the death rate. Tell students worldwide, the human birth rate is currently three times the death rate
Concept
This activity demonstrates the relationship between birth and death rate and of population growth within a finite space.
Procedure:
1. Fill a bucket with water and add food coloring so it will be more visible in a clear container. Place the empty, clear container with the towel under it in front of the class.
2. Ask for two volunteers from the class to assist. Designate number 1 for one student and number 2 for the other. Each student should tape the appropriate number tag to the student.
3. Hold up the clear container: This will represent the world, and the colored water in the bucket will represent people. Number 1, will add people to the world by pouring dippers of water into the container. Number 2, will be taking people from the world by scooping water out of the clear container and pouring it back into the bucket. At this time, the world's birth rate is three times the death rate. Based on that fact, who should receive the large dipper? Who should use the small dipper?
Discussion:
1. Why did the water level rise steadily
2. What would this mean if the clear container really was the world?
Source: People and the Planet, Zero Population growth, Inc. Wash., D. C. 1996.
Lesson Plan III
Overview: In a society where tradition often clashes with modern ideology, decision making may be taxing.
Goal: To act out the decision making process of a married couple in an urban area in Connecticut discussing whether or not they will add another child to their family.
Objective: student will (1) discuss attitudes affecting family size in Connecticut; (2) make a decision after listening to opinion.
Skills To Be Developed
1. Role Playing
2. Persuasive speaking
3. Problem Solving
Do This:
Read students a scenario that describes a specific situation involving a decision concerning family size in Connecticut. Choose six students to be the participants in the role playing activity. Select three males and three females and give each student a description of their character. All students who are not role players will pretend that they are the couple who must make the important decision about whether or not to have another child. Poll the students. Did you choose to have another child? Why or why not? What if any particular argument, was the most important in affecting your decision?
[Source: FAO Photo Library]
Primary Health Care
Improvements to urban health services would have significant impact. More comprehensive health coverage, including immunization campaigns, would improve nutrition among the urban poor by preventing gastrointestinal and infectious diseases, promoting adequate diet among pregnant and lactating women and encouraging proper infant and child feeding. However, urban health services often observe an “inverse care law”: those in greatest need of care have the poorest access to it. Few governments have formulated urban health policies giving priority to the poor and, even when such plans and programmes do exist, their implementation is hampered by resource shortages aggravated in recent years by economic recession. A further barrier is the chaotic administration typical of many overcrowded Third World cities.
Agencies agree, therefore, on the need to adapt WHO's Primary Health Care (PHC) approach - until now a mainly rural phenomenon - to the needs of the urban poor. Described as a “renaissance in community health”, PHC is a strategy encompassing total, primary-level health coverage as well as action to attack the fundamental causes of health problems through policies establishing equity in employment, income, education, housing and planning. One increasingly popular instrument for applying this approach in poor urban areas is neighbourhood health programmes, the equivalent district level PHC arrangements promoted by WHO in rural areas. While no established blueprint for such programmes exists, successful neighbourhood schemes have emerged in Cali, Addis Ababa, Djakarta and Manila, usually based on community health centres with a wide deployment of health workers and emphasis on public health education campaigns. Coverage so far has been limited, but the neighbourhood programmes could be expanded and consolidated. Essential to the PHC approach, WHO stresses, is the parallel development of a decentralized network of hospitals supporting the primary system. This reorganization was successful in Cali, where the strengthening of peripheral health units benefited particularly the poor populations of outlying barrios.
Population Distribution
Population distribution means the pattern of where people live. World population distribution is uneven. Places which are sparsely populated contain few people. Places which are densely populated contain many people. Sparsely populated places tend to be difficult places to live. These are usually places with hostile environments e.g. Antarctica. Places which are densely populated are habitable environments e.g. Europe.
Population Density
Population density is a measurement of the number of people in an area. It is an average number. Population density is calculated by dividing the number of people by area. Population density is usually shown as the number of people per square kilometer. The map below is a choropleth (shading) map and illustrates population density. The darker the color the greater the population density.
There are a range of human and natural factors that affect population density. The tables below illustrate this.
Physical Factors High Density Low Density
Relief
(shape and height of land) Low land which is flat e.g. Ganges Valley in India High land that is mountainous e.g. Himalayas
Resources Areas rich in resources (e.g. coal, oil, wood, fishing etc.) tend to densely populated e.g. Western Europe Areas with few resources tend to be sparsely populated e.g. The Sahel
Climate Areas with temperate climates tend to be densely populated as there is enough rain and heat to grow crops e.g. UK Areas with extreme climates of hot and cold tend to be sparsely populated e.g. the Sahara Desert
Population Change
The world's population is growing very rapidly. In 1820 the world's population reached 1 billion. In 1990 it reached 6 billion people.
This rapid growth in population has been called a population explosion.
The major reason for population changes, whether in an individual country or for the whole world, is the change in birth and death rates. The birth rate is the number of live babies born in a year for every 1000 people in the total population. Death rates are number of people dying per 1000 people. When birth rates are higher than death rates the population of an area will increase.
Over the past 150 years improvements in health care and sanitation around the world have led to a drop in the death rate. While birth rates have dropped in MEDCs, birth rates are still high in LEDCs. Therefore the number of people in the world has grown rapidly.
Life Expectancy
Life expectancy is the average age a person can expect to live to in a particular area. Life expectancy can be used as an indicator of the overall 'health' of a country. From this figure you can determine many features of a country e.g. standard of living. As a general rule the higher the life expectancy the healthier (or developed) a country is.
The Demographic Transition Model
The Demographic Transition Model attempts to show how a population change as a country develops.
The model is divided into four stages.
Stage 1
Birth rate and death rate are high - low natural increase - low total population
Stage 2
Birth rate is high - death rate is falling - high natural increase (population growth)
Stage 3 Falling birth rate - low death rate - high natural increase (population growth)
Stage 4
Birth rate and death rate is low - low natural increase - high total population
The Demographic Transition Model does not take into account migration.
Population Structure / Population Pyramids
The population structure for an area shows the number of males and females within different age groups in the population. This information is displayed as an age-sex or population pyramid. Population pyramids of LEDCs (Less Economically Developed Countries) typically have a wide base and a narrow top. This represents a high birth rate and high death rate. Population pyramids of MEDCs (More Economically Developed Countries) typically have a roughly equal distribution of population throughout the age groups. The top obviously gets narrower as a result of deaths. Population pyramids are used to show the structure of the population according to age and sex.
"Earth's present human population is over 6,200 million."
Using the numbers above, we see that human population increased by a factor of 1.84 (just less than doubled) in the60-year period from 1900 to 1960. It doubled (roughly) in the40-year period from 1960 to 2000. In absolute numbers, the picture is more revealing. In the 60-year period from 1900 to 1960, human population increased by 1,389 million. In the
40-year period from 1960 to 2000, it increased by 3,041 million. Consider that recent "doubling in 40 years" for the period 1960 to 2000 (increase of just over 3 billion). This is an average increase of 75 million per year - or
about 205,000 per day, 8,500 per hour, 140 per minute. Now consider the 10-year period from 1990 to 2000.The increase for that period is 796 million. This is an average increase of 79.6 million per year - or about 218, 000 per day, 9,100 per hour, 150 per minute.