I.
Chapter 6 Miller Review
Chapter 6: The Human Population and Its Impact
a. 6-1: How Do Environmental Scientist Think about Human Population Growth?
i. Demogaphers – population experts, recognize three important growth trends
1. In recent decades the rate of population growth has slowed but the world’s
population is still growing
2. Demographers recognize that geographically human population growth is
unevenly distributed and this patter is expected to continue
a. Three most populous countries are, in order, China, India, and the US
3. The movement of people from rural areas to cities
ii. Cultural Carrying Capacity – the maximum number of people who could live in
reasonable freedom and comfort indefinitely, without decreasing the ability of the
Earth to sustain future generations
b. 6-2: What Factors Influence the Size of the Human Population?
i. Crude Birth Rate – the number of live births per 1,000 people in a population in a
given year
ii. Crude Death Rate – the number of deaths per 1,000 people in a population in a given
year
1. Human populations grow or decline in a particular countries, cities, or other
areas through the interplay of three factors: births (fertility), deaths
(mortality), and migration
iii. Population Change – calculated for an area by subtracting the number of people
leaving a population (through death or emigration) from the number entering it
(through birth and immigration) during a specified period of time (usually 1 year)
1. Population Change = (Births + Immigration) – (Deaths + Emigration)
2. Fertility Rate – a measure of how many children are born in a population
over a set period of time.
3. Replacement-Level Fertility Rate – the average number of children that
couples in a population must bear to replace themselves
a. Any fertility rate above the replacement level will cause a population
to grow
4. Total Fertility Rate (TFR) – The key factor affecting human population
growth and size; the average number of children born to the women in a
population during their reproductive years
a. Baby Boom – between 1946 and 1964
b. Immigration has become a political issue in the United States
iv. The environmental impact of a population is obtained by multiplying the effects of
three factors:
1. Population Size
2. Affluence (and resulting high rates of resources use per person)
3. Technology
v. Factors that affect a country’s average birth rate and TFR:
1. The importance of children as a part of the labor force (less developed
countries)
2. The cost of raising and educating children (lower in more-developed
countries)
3. The availability of, or lack of, private and public pensions systems
4. Infant deaths
5. Urbanization (have better access to family planning services and tend to have
fewer children)
6. Educational and employment opportunities available for women (TFR tend
to be low when women have access to education and paid employment
outside the home)
7. Average age at marriage
8. Availability of legal abortions
9. Availability of reliable birth control methods
10. Religious beliefs, traditions, and cultural norms
vi. Rapid Growth of the world’s population over the past 100 years is not primarily the
result of a rise in the birth rate. Instead, it has been caused largely by declining
death rates
1. Living longer and fewer infant are dying because of increased food supplies,
improvements in food distribution, better nutrition, medical advances such
as immunizations and antibiotics, improved sanitation, and safer water
supplies
vii. Life Expectancy – the overall health of people in a country or region; which for any
given year is the average number of years a person born in that year can be
expected to live.
viii. Infant Mortality Rate – overall health in a population; the number of babies out of
every 1,000 born who die before their first birthday.
1. Viewed as one of the best measure’s of a society’s quality of life because it
reflects a country’s general level of nutrition and health care
a. High infant mortality usually indicates insufficient food
(undernutrition), poor nutrition (malnutrition), and a high incidence
of infectious disease
i. US ranked 44th among all nations in terms of infant mortality
rate for two main reasons:
1. The general inadequate health care for poor women
during pregnancy as well as their babies after birth
2. Drug addiction among many pregnant women
ix. Migration – the movement of people into (immigration) and out of (emigration)
specific geographic areas
1. Seeing jobs, economic improvement, safety from religious persecution, ethnic
conflicts, political oppression, war
2. Environmental Refugees – people who have to leave their homes because of
water or food shortages, soil erosion, or some other form of environmental
degradation or depletion
c. 6-3: How Does a Population’s Age Structure Affect Its Growth or Decline?
i. Age Structure – the number or percentages of males and females in young, middle,
and older age groups in that population
1. Plotting the percentages or numbers of males and females in the total
population in each of three age categories:
a. Prereproductive (ages 0-14)
b. Reproductive (ages 15-44)
c. Postreproductive (ages 45 and older)
2. A country with a large percentage of its people younger than age 15
(represented by a wide base) will experience rapid population growth
a. Demographic Momentum – the number of births in such a country will
rise for several decades even if women have an average of only one or
two children each, due to the large number of girls entering their
prime reproductive years
3. If a population’s decline is gradual, its harmful effects usually can be
managed
ii. A large number of deaths from AIDS can disrupt a country’s social and economic
structure by removing significant numbers of young adults from its population
1. Unlike hunger and malnutrition, which kills mostly infants and children, AIDS
kills primarily young adults and leaves many children orphaned
2. Worldwide AIDS is the leading cause of death for people of ages 15-49
a. A number of harmful effects:
i. Sharp drop in average life expectancy
ii. The loss of productive young-adult workers and trained
personal
iii. Essential services they could provide are therefore lacking
d. 6-4: How Can We Slow Human Population Growth?
i. The three most effective ways to slow or stop population growth are:
1. To reduce poverty, primarily through economic development and universal
primary education
2. To elevate the status of women
3. To encourage family planning and reproductive health care
ii. Demographic Transition – as countries become industrialized and economically
developed, their populations tend to grow more slowly
iii. A number of studies show that women tend to have fewer children if they are
educated, have the ability to control their own fertility, earn an income of their own,
and live in societies that do not suppress their rights
1. Because sons are more valued than daughters in many societies, girls are
other kept at home to work instead of being sent to school
2. A change (from the bottom-up) driven by individual women will play an
important role in stabilizing populations, reducing poverty and
environmental degradation, and allowing more access to basic human rights
iv. Family Planning – provides educational and clinical services that help couples
choose how many children to have and when to have them; most of them provide
information on birth spacing, birth control, and health care for pregnant women and
infants
1. Benefits:
a. A major factor in reducing the number of births throughout most of
the world
b. Also reduced the number of abortions performed each year
c. Decreased the numbers of mothers and fetuses dying during
pregnancy
d. Has finical benefits:
i. Thailand, Egypt, and Bangladesh saves $10-$16 in health,
education, and social-service cost by preventing unwanted
births
2. Problems:
a. According to the UN Population Fund – about 42% of all pregnancies
in less-developed countries are unplanned and about 26% end with
abortion
b. An estimated 215 million couples in less-developed countries want to
limit their number of children and determine their spacing, but they
lack access to family planning services
3. Improvements:
a. Some analysts call for expanding family planning programs to educate
men about the importance having fewer children and taking more
responsibility for raising them
b. Develop more effective birth control methods for men
v. The past 50 years has been the sharp reduction in the rate of population growth
resulting from a combination of the reduction of poverty through economic
development, empowerment of women, and the promotion of family planning
1. India:
a. India has tried to control its population growth with only modest
success
b. Has the world’s larges economy and a thriving and rapidly growing
middle class of more than 100
c. Class of consumers will enlarge India’s ecological footprint, as more
Indians use more resources with every passing year
d. The country faces a number of serious poverty, malnutrition, and the
environmental problems that could worsen as its population
continues to grow rapidly
e. Two factors help to account for larger families in India
i. Most poor couples believe they need several children to work
and care for them in old age
ii. The strong cultural preference in India for male children
means that some couples keep having children until they
produce one or more boys
f. Critical resource and environmental problems
i. Cropland is degraded as a result of soil erosion and
overgrazing
ii. Water is seriously polluted, sanitation services are often
inadequate
g. Undergoing rapid economic growth
2. China:
a. The world’s most populous country
b. 1960’s: China’s large population was growing so rapidly that there
was a serious threat of mass starvation. To avoid this, government
officials decided to take measures that eventually led to the
establishment of the world’s most extensive, intrusive, and strict
family planning and birth control program (One Child Law)
c. Over time, China’s rapidly growing middle class will consume more
resources per person, expanding China’s ecological footprint within
its own borders and in other parts of the world that provide it with
resources