C H A P T E R 7 Human Populations

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Transcript C H A P T E R 7 Human Populations

Chapter 7: Human Populations
7.1 Population Growth
• Human populations grew slowly until relatively
Population Growth
• Until the Middle Ages, human populations were held
in check by diseases, famines and wars, and thus
grew very slowly.
It took all of human history until 1800 to reach 1 billion.
150 years to reach 3 billion
12 years to go from 5 to 6 billion
Human population tripled during the twentieth century.
• “Natural Population Control” = Disease, Famine, War
Population Growth
1 billion: 1810
2 billion: 1925 Doubling Time 115 years
3 billion: 1959
4 billion: 1974 Doubling Time 52 years
5 billion: 1987
6 billion: 1999 Doubling Time 40 years
7 billion: 2012
Population Growth
• World War II (1939-45) killed about 60
million people in 6 years (27,000/day)
• Global population 2.3 billion 1940
• Global population 2.5 billion 1950
• Population growth 20,000,000 per year
• Population growth 55,000 per day
– 2x War Death Rate
• At no time did the war offset population
growth for more than a few days
7.2 Perspectives On Population
• Does environment or culture control
human populations?
• Technology can increase carrying
capacity for humans
• Population growth could bring
7.3 Many Factors Determine
Population Growth
• How many of us are there?
– Even today we only have estimates
– Past population figures are crude
• Fertility measures the number of children born to
each woman
– Replacement = 2.1
– Not all women have children and not all survive
• Mortality is the other half of the population equation
– Much of our population growth is reduced mortality
– Simple sanitation goes a long way
7.3 Many Factors Determine
Population Growth
• Life span and life expectancy describe our
potential longevity
– Much of the change is reduced infant mortality
• Living longer has demographic implications
– More elderly need care
– Working longer reduces upward mobility
• Emigration and immigration are important
demographic factors
– Latino influx into the U.S.
– The “Eurabia” panic
Limits To Growth
• Thomas Malthus (1798) argued human
populations tend to increase exponentially while
food production is plentiful.
– Humans multiply to use available food supply and
are vulnerable to collapse.
– Human population only stabilized by “positive
• “Positive” = “Actively Opposing,” not Necessarily
– Humans unlikely to voluntarily reduce birth rates.
Karl Marx
• Population growth is a symptom rather than a
root cause of poverty and other social
• Real causes of these problems are exploitation
and oppression.
– The way to slow population growth and alleviate
many social problems is through social change.
Malthus and Marx Today
• Neo-Malthusians - Believe we are approaching, or
have already surpassed, the earth’s carrying
– We should make over-population issues our first
• Neo-Marxists - Believe eliminating oppression and
poverty through social change is the only solution to
the population problem.
– Wealth and resource distribution must be
7.4 Ideal Family Size Is Culturally And
Economically Dependent
• Many factors increase our desire for children
– Labor
– Old Age Support
– Status
– Love
• Other factors discourage reproduction
– Cost (Monetary, Lifestyle)
– Negative Status
• Could we have a birth shortage?
7.5 A Demographic Transition Can
Lead To Stable Population Size
• Economic and social development influence
birth and death rates
• There are reasons to be optimistic about
• Many people remain pessimistic about
population growth
• Social justice is an important consideration
• Women’s rights affect fertility
7.6 Family Planning Gives Us Choices
• Fertility control has existed throughout history
– Infanticide was the leading method (exposing or
abandoning infants)
– Oedipus and Romulus and Remus were two Famous
Examples in Mythology
• Infanticide Condemned by Judaism and Christianity
– the exposure of infants is forbidden, which has become
a very ordinary piece of wickedness among other
nations by reason of their natural inhumanity
(Philo Judaeus of Alexandria, Special Laws III c. 30 AD)
– Thou shalt not murder a child by abortion, nor again
shalt thou kill it when it is born.
(Epistle of Barnabas c. 120 AD)
Romulus and Remus
7.7 What Kind Of Future Are We
• Religion and politics complicate family
– Religious Opposition
– Fear of Being “Out-Bred” by Rivals
– Suspicion of Motives
– Concerns About Intrusion
– Rising cost of Labor and Services
– Decreasing Tax Base
The Role of Technology
• Technological optimists argue that Malthus
was wrong in his predictions because he
failed to account for scientific progress.
– Current burst of growth was stimulated by the
scientific and industrial revolutions.
– Malthus never denied these could be factors
– He particularly stressed the role of education
Technological Optimism
Technological Optimism
The Meaning of Finite
You cannot put an infinite amount of
anything into a finite space
• Therefore we will eventually run out of
You cannot get an infinite amount of
anything out of a finite space
• Therefore we will eventually run out of
new resources
At 2% Per Year
• In 573 years there will be one person per
square meter over the whole earth
• In 1546 years the mass of humanity will equal
the mass of the earth
• No exponential growth can continue
What About Interest?
• At 2% per year, a penny invested in 1 AD
would be worth $1.6 x 1015 in 2000 AD
• Total GNP of World = $60 x 1012
• At 4%, couldn’t be paid in gold because it
would outweigh the earth
• Works if interest paces growth of economy
• Offsets: Inflation, Default, Collapse
In the Long Run, All Growth is Limited
Environmental Resistance
Malthusian: Overshoot plus crash
Logistic: Steady Limit
Human Population Will Stop Growing
– When?
– How?
– Overshoot plus Dieback = Dead Babies, Starvation,
War, Genocide, Epidemics
• Positive: Change More Change
– More people more babies  more people…
• Negative: Change Opposing Force
– More babies  more expense  Reduced Birth
• Logistic growth
– Early positive feedback phase
– Final negative feedback phase
Carrying Capacity of Earth
• Solar Energy about 10,000 times global
energy use
• Global energy use = sunlight on 20,000
square miles (West Virginia)
• Globally about 1/3 of arable land is used
for crops
• If U.S. (5% of population) uses 25% of
resources, will take 5 times earth’s
resource output to raise everyone to our
Why Many Oppose Population Control
Suspicion of Government
• Abuse of Police Powers
• Undermine Family Authority
• Racial Issues
Why Many Oppose Population Control
• Declining markets
• Diminished labor pool
• Reduced Military Manpower
• Reduced Tax Base
• Increased Wages and Costs
Why Many Oppose Population Control
• Pressure for Abortion
• Birth Control
• Effects on Sexual Conduct
Population Growth Rates
What Drives Population Growth?
• Despite Vatican stance on birth control, most
Catholic countries growing slowly
• Fastest growth in Africa and South Asia
• Many of the fastest growing countries are
• Economic value of large families (farm labor,
elder care and support)
• Status attached to high fertility
Human Demography
Demography - Encompasses vital statistics about
people such as births, deaths, distribution,
and population size.
• October 12, 1999, UN officially declared the
human population reached 6 billion.
– Estimation at best.
• 7 billion: October 2011 (UN), March 2012
(Census Bureau)
Population Density (persons / square
“Third World”
Originally a Cold War Term
First World: U.S. and Allies
Second World: USSR and Allies
Third World: Non-Aligned
“Third World”
• First World: Developed
• Second World: Semi-Developed
• Third World: Non-Developed
• Close similarity to Cold War meaning of Third
North vs. South?
Two Demographic Worlds
First is poor, young, and rapidly growing.
• Less-developed countries.
– Africa, Asia, Latin America
– Contain 80% of world population, and will
account for 90% of projected growth.
Second is wealthy, old, and mostly shrinking.
• North America, Western Europe, Japan.
– Average age is about 40.
– Populations expected to decline.
Global Corruption
Human Rights Index
Religious Freedom
Estimated Human Population Growth
Fertility and Birth Rates
• Crude Birth Rate - Number of births in a year per
thousand. (Not adjusted for population
• Total Fertility Rate - Number of children born to an
average woman in a population during her life.
• Zero Population Growth - Occurs when births plus
immigration in a population just equal deaths plus
Mortality and Death Rates
Crude Death Rate - Number of deaths per
thousand persons in a given year.
• Poor countries average about 20 while
wealthier countries average about 10.
– Some rapidly growing countries have very
low crude death rates compared to
slower growing countries, due to a higher
proportion of young people in the
Population Growth Rates
• Natural Increase
– (Crude Birth Rate - Crude Death Rate)
• Total Growth Rate
– Includes immigration and emigration
Life Span and Life Expectancy
Life Expectancy - Average age a newborn can expect
to attain in any given society.
• Declining mortality is the primary cause of most
population growth in last 300 years.
• Worldwide, average has risen from 40 to 65.5
over the past century.
– Greatest progress has been in developing
– Largely due to curbing infant mortality
Life Expectancy-1930
Life Expectancy-1960
Life Expectancy-1990
Demographic Implications of Living
A population growing rapidly due to natural
increase has more young people than a
stationary population.
• Both rapidly and slowly growing countries
can have a problem with dependency ratio.
– The number of non-working compared to
working individuals in a population.
Emigration and Immigration
• Emigration and Immigration play a large role
in human population dynamics.
– Developed regions expect 2 million immigrants a
year for next 50 years.
– Immigration is a controversial issue. “Guest
workers” often perform dangerous or
disagreeable work, while being paid low wages
with few rights.
– Locals complain immigrants take away jobs and
overload social services.
Population Growth, Opposing Factors
Pronatalist Pressures
• Factors that increase the desire for children.
– Source of pleasure, pride, comfort.
– Source of support for elderly parents.
– Current source of family income.
– Social Status
– Replace members in society as they die.
• Boys frequently valued more than girls.
Birth Reduction Pressures
• Higher education and personal freedom for
women often result in decisions to limit
– When women have more opportunities to earn
a salary, they are less likely to have children.
– Education and socioeconomic status are usually
inversely related to fertility in wealthier
Birth Reduction Pressures
• In developing countries, higher income often
means families can afford more children,
thus fertility often increases.
• In less-developed countries, adding another
child to a family usually does not cost much,
while in developed countries, raising an
additional child can carry significant costs.
Demographic Transition
Model of falling death rates and birth rates
due to improved living conditions
accompanying economic development.
• Pre-Modern Society - Poor conditions keep
death rates high, thus birth rates are
correspondingly high.
• Economic Development brings better
conditions and standard of living thus death
rates fall. Birth rates stay constant or even
Demographic Transition
Eventually, birth rates begin to fall.
• Populations grow rapidly in time
between death rates and birth rates
Developed Countries - Transition is
complete and both death and birth
rates are low and population is in
Demographic Transition
United States Birth
“Pig in a python”
Optimism or Pessimism
• Some demographers believe the
Demographic Transition is already taking
place in developing countries, and world
population should stabilize during the next
• Others argue that many poorer countries are
trapped in the middle phase of transition,
and that their populations are growing so
rapidly that human demands exceed
sustainable resource yields.
Social Change
Still other demographers believe that in
order for the Demographic Transition
model to work, resources must be
distributed more equitably.
• The world has enough natural
resources, but inequitable social and
economic systems cause
Family Planning
• Family Planning allows couples to determine
the number and spacing of their children.
• Birth Control - Any method used to reduce
– Traditional Methods
Long breast-feeding
Taboos against intercourse while breast-feeding
Folk medicines
Birth Control
Current Methods
• Avoidance of sex during fertile periods.
• Mechanical barriers preventing contact
between sperm and egg.
• Surgical prevention of sperm or egg release.
• Chemical prevention of sperm or egg
maturation, release, or implantation.
• Physical barriers to implantation.
• Abortion
Future Of Human Populations
Most demographers believe the world
population will stabilize sometime during the
next century.
• Projections of maximum population size:
– Low
– Medium
– High
One Last Demographic Effect of
Population Growth