Chapter 8: Human Population
Section 1: Trends in Human Population
Growth
History of Human Population Growth
o Technological advances, especially in agriculture
and industry, changed the ways people lived and
triggered remarkable increases in population size.
o About 10,000 years ago, many human societies
changed from roaming hunter-gatherers to settled
farmers.
Met nutritional needs more easily and people lived
longer and more children survived to adulthood
o During the Industrial Revolution many societies
started to shift from a rural life focused on
agriculture and goods made by craftspeople to
urban societies powered by fossil fuels
People began to understand that many deadly
diseases are caused by organisms (germs) that
spread from person to person.
• Living conditions in cities became cleaner
• Doctors began washing their hands before
moving from one patient to the next
• Mass production of soap and cotton clothes
helped slow the spread of disease
The advances in industry made it possible to
mass produce medical instruments and
medicines
Large machines that make it possible to plant
and harvest food in mass quantities were
invented, along with pesticides and synthetic
fertilizers.
Recent Trends in Human Population Growth
o In recent years the human population growth
rate has decreased, but the population still
continues to grow.
o Infant mortality is the number of babies out of
1000 that die during their first year of life
o Life expectancy is the average number of years
an individual is expected to live.
o When babies have a greater chance of survival
and adults live longer, a population is likely to
grow
o Growth rate refers to how a population
changes in size during a specific period of time
Recently the growth rate has started to decline to
about 1.2%
Vary by region
o Advances have allowed humans to temporarily
increase the species’ carrying capacity – the
number of organisms that an environment can
support
Describing the Human Population
o Demographers study the size, density, and
distribution of human populations.
o The study of human population statistics is
called demography.
o The human population size is roughly 6.8
billion, but the exact number changes every
second.
Current World Population
o Population density describes how many
people live per square mile or square
kilometer.
o Population density is highest in regions with
temperate and tropical climates such as
China, Europe, Mexico, and India, and it is
lowest in regions with extreme climates
such as deserts and tundra.
o The human population is clumped, rather
than random or uniform.
This uneven distribution means that some
areas bear more of an environmental impact
than others.
Section 2: Prediction Population
Growth
Fertility Rate
o Fertility rate helps demographers predict
the rates at which populations will grow in
the future
o Births add individuals to the global
population and deaths remove them
o Immigration and emigration affect the
population size of particular regions
o Total fertility rate is the average number of
children a female member of a population
has during her lifetime.
Helps demographers predict if a population’s
size will increase, decrease, or stay the same
o Replacement fertility is the total fertility
rate for a nation that would keep its
population size stable.
Differs from nation to nation
About 2.1
Journal
In the United States, Canada, and many European
nations, the total fertility rate has fallen below the
replacement rate. What economic and social
consequences do you think might result from below
replacement fertility rates?
Age Structure and Sex Ratios
o Age structure and sex ratios define a
population’s potential for growth
o Age structure describes the relative
numbers of organisms of each age within a
population
Often represented by a graph called an age
structure diagram which shows how many
males and females there are in each age group
A population with many young people
compared to older people is likely to
experience rapid population growth in the
future
A population with fewer younger people will
likely decrease in the future
o Sex ratio is the number of males compared
to females in a population (shown in age
structure diagrams)
Naturally occurring sex ratio has slightly more
males
Human activities can skew the sex ratio one
way or another
• Ex: males that emigrate to find work, culture
that values sons more than daughters
The Demographic Transition
o The demographic transition may explain the
reason that some industrialized nations have
experienced a large drop in birthrates and
death rates.
o The demographic transition is a model that
explains the change from high birthrates and
death rates to a condition of low birthrates and
death rates.
The result of economic growth that has led to
social changes
Four-stage Process:
• The Pre-Industrial Stage
o High death rates and birth rates
o Widespread disease and poor medical care
o Unreliable food and water supplies
o No family planning methods available
o People want larger families
o High infant mortality
o Population does not experience much growth
• The Transitional Stage
o Started by industrialization
o Death rates decline as food production
increases and medical care improves
o Birth rates remain high
o Rate of population growth increases
• The Industrial Stage
o Increased job opportunities for women
o Birth control available
o Birth rates decrease
o Rate of population growth decreases
• The Post-Industrial Stage
o Both birth rates and death rates fall to low and
stable levels
o Population sizes stabilize or decline slightly but
are much higher than they were at the preindustrial stage
Pre-Industrial
Transitional
Industrial
Post-industrial
Social Factors
o Social factors, such as wealth and education,
affect a nation’s population growth and its
resource use
o The term developing nation refers to nations
with moderate or low income
China, Mexico, South America, Indonesia, and
eastern Europe
Tend to have higher fertility rates, infant mortality
rates, and death rates
Life expectancy is typically lower
Can have a higher frequency of diseases such as
AIDS and tuberculosis
High population growth
o Developed nations are high-income nations
United States, Canada, western European
nations, Australia, New Zealand, Japan, and
some Arab states
Lower population growth
o Many developing nations experiencing rapid
population growth have programs to
encourage citizens to have smaller families
Thailand relies on an education-based approach to
family planning
In 1994, The United Nations hosted a conference in
Cairo on population and development
• Urged governments to offer better education
and healthcare and address social needs that
influence population size
o Better educational opportunities for women
are closely tied to declining fertility rates
Section 3: People and Their
Environments
Impacts of Populations
o Humans have an enormous impact on their
environment
o The type of environmental impact varies
greatly among societies
Affluent societies
• People tend to consume more food, purchase
more items, produce more wastes, and live in
larger homes that use more energy
• Individuals tend to have larger ecological
footprints
Poor societies
• In some nations where population growth is
outpacing the nation’s economic growth,
governments are so overwhelmed they
cannot provide infrastructure that protects
people and the environment
• Poverty may force people to engage in
environmentally harmful activities just to
survive
• The ever-increasing need for more farmland,
land to raise livestock, and wood contributes
to deforestation
• Emerging diseases have arisen because
human and animal habitats have merged
o The wealth gap refers to the difference in
assets and income between individuals in a
society or between nations
The richest one fifth of the world’s people uses
86% of the world’s resources
o As developing nations develop, they may
encounter new sets of problems
Decreasing natural resources
Increased pollution
o Quality of life refers to how well an
individual lives
Includes having basic life necessities as well as
intangible elements such as access to
healthcare and education, recreational time,
and feelings of security.
Impacts of Technology
o Technology can have both negative and
positive impacts on the environment
o The environment has often paid the price
for human achievements because many of
these technologies have involved
exploitation of resources such as soils,
minerals, fossil fuels, old-growth forests,
and the oceans.
o In recent years less harmful technologies
have begun reducing environmental impact.