The Human Population & Earth’s Carrying Capacity A Real-Life Game of Musical Chairs Objectives Describe how the size and growth rate of the human population

The Human Population & Earth’s Carrying Capacity A Real-Life Game of Musical Chairs

Objectives

• Describe how the size and growth rate of the human population has changed in the last 200 years.

• Define four properties that scientists use to predict population sizes.• Make predictions about population trends based on age structure.• Describe the four stages of the demographic transition.• Explain why different countries may be at different stages of the demographic

transition.• Describe three problems caused by rapid human population growth.• Compare population growth problems in more-developed countries and less

developed countries.• Analyze strategies countries may use to reduce their population growth.• Describe worldwide population projections into the next century.


National Science Education Standards

Content Standard F – Population Growth• Populations grow or decline through the combined effects of births and deaths, and

through emigration and immigration. Populations can increase through linear or exponential growth, with effects on resource use and environmental pollution.

• Various factors influence birth rates and fertility rates, such as average levels of affluence and education, importance of children in the labor force, education and employment of women, infant mortality rates, costs of raising children, availability and reliability of birth control methods, and religious beliefs and cultural norms that influence personal decisions about family size.

• Populations can reach limits to growth. Carrying capacity is the maximum number of individuals that can be supported in a given environment. The limitation is not the availability of space, but the number of people in relation to resources and the capacity of earth systems to support human beings. Changes in technology can cause significant changes, either positive or negative, in carrying capacity.


Key Terms

• Demography• Age Structure• Survivorship• Fertility Rate• Migration• Life Expectancy• Demographic Transition• Infrastructure• Arable Land• Urbanization• Least Developed Countries


Focus Questions

1. Describe how the size and growth rate of the human population has changed in the last 200 years.

2. Define four properties that scientists use to predict population sizes.3. Explain what we can predict about a population’s likely growth rates based

on its current age structure.4. Describe the four stages of the demographic transition.5. Explain why the oldest people in a population may be much older than the

average life expectancy.6. Describe three problems caused by rapid human population growth.7. Compare the population growth in more-developed countries to population

growth in less developed countries.8. Describe worldwide population projections for the next 50 years.


Demography is the study of the characteristics of populations, especially human populations.


The Human Population Over Time


The Human Population Over Time

In the past 200 years, the population has increased from about 1 billion to over 6 billion and the growth rate has increased. This change was made possible by improvements in:

1. Healthcare2. Nutrition3. Sanitation


Forecasting Population Size

Scientists use the following four properties to predict population sizes:

1. Age Structure2. Survivorship3. Fertility Rates4. Migration


Forecasting Population Size – Age Structure

Age structure is the classification of members of a population into groups according to age or the distribution of members of a population in terms of age groups.





What can we predict about a population’s likely growth rates based on its current age structure?

If a population has more young people than older people, the population size will probably increase as the young people grow up and have children.


Forecasting Population Size – Survivorship

Survivorship is the percentage of newborn individuals in a population that can be expected to survive to a given age.


Forecasting Population Size – Survivorship


Forecasting Population Size – Fertility Rates

Fertility rate is the number of births (usually per year) per 1000 women of childbearing age (usually 15 to 44).


Forecasting Population Size – Fertility Rates


Forecasting Population Size – Migration

Migration is any movement of individuals or populations from one location to another; specifically, a periodic group movement that is characteristic of a given population or species.


Forecasting Population Size – Migration


Declining Death Rates

Life expectancy is increasing!

Life expectancy is the average length of time that an individual is expected to live.











Life expectancy is sometimes deceptive.

The oldest people in a population may be much older than the average life expectancy.

Life expectancy is affected by infant mortality. If infant mortality is high, it brings down life expectancy. Many people live past life expectancy because the number is an average of all life spans.


The Demographic Transition

The demographic transition is the general pattern of demographic change from high birth and death rates to low birth and death rates, as observed in the history of more-developed countries.


The Demographic Transition – Stages of the Transition


The Demographic Transition – Stages of the Transition

Four stages:

1. Stage 1 (Preindustrial) – Birth and death rates are high so the population grows slowly or not at all.

2. Stage 2 (Transitional) – Birth rates remain high but death rates decline as hygiene, nutrition, and education improve. The population increases.

3. Stage 3 (Industrial) – Birth rates and death rates are about equal, so the population stabilizes.

4. Stage 4 (Postindustrial) – Birth rates decline while the death rates stay low, so the population decreases.


The Demographic Transition – How to decline birth rates…

Four significant factors that cause a decline in birth rate are:

1. Increased education for women2. Increased economic independence for women3. Increased cost per child4. Increased availability of pensions for elderly people












Changing Population Trends

Rapid human population growth leads to serious problems.

A rapidly growing population uses resources at an increased rate and can overwhelm the infrastructure of a community.

Infrastructure is the basic facilities of a country or region, such as roads, bridges, and sewers.


Changing Population Trends - Infrastructure


Problems of Rapid Growth

Three major problems associated with rapid human population growth are:

1. Fuel Shortages2. Unsafe Water3. Impacts on Land


Problems of Rapid Growth – Fuel Shortages


Problems of Rapid Growth – Fuel Shortages


Problems of Rapid Growth – Unsafe Water


Problems of Rapid Growth – Impacts on Land





Negative impacts on land caused by rapid human population growth include:

1. Shortage of Arable Land

Arable land is farmland that can be used to grow crops.

2. Urbanization

Urbanization is an increase in the ratio or density of people living in urban areas rather than rural areas.












A Demographically Diverse World

Demographers have divided the world into two regions:

1. More Developed Countries – higher average incomes, slower population growth, and diverse industrial economies.

2. Less Developed Countries – lower average incomes, rapid population growth, and diverse industrial economies.




A Demographically Diverse World – Least Developed Countries


A Demographically Diverse World – Least Developed Countries

Least developed countries are countries that have been identified by the United Nations as showing the fewest signs of development in terms of income, human resources, and economic diversification.









Less developed countries typically have higher birth rates and lower life expectancies than more developed countries.


Managing Development and Population Growth

The governments of some countries have tried to reduce birth rates by employing the following strategies:

1. Public advertisements2. Family planning programs3. Economic incentives4. Legal punishments










Growth Is Slowing


Growth Is Slowing


Growth Is Slowing


Growth Is Slowing

The worldwide population is expected to increase for the next 50 years and reach between 8 and 11 billion. The exact amount of increase is uncertain.


Will there be enough chairs for everyone?


Will there be enough chairs for everyone?

HOMEWORK

Keep checking the website for updates – readings, lecture videos, lecture notes, assessment data, assessment answer keys.

Study the readings for a formative quiz at the beginning of the next class.

All current and upcoming material will be posted on the “Home” page.

Documents

The Human Population & Earth’s Carrying Capacity A Real-Life Game of Musical Chairs Objectives Describe how the size and growth rate of the human population