THE HUMAN
POPULATION
CHAPTER 7
EARTH’S CARRYING CAPACITY
• Every 5 days the global human population
increases by roughly 1 million lives:
• 1.8 million infants born - 800,000 people die
• What factors influence Earth’s carrying capacity for
humans?
• Food, water, timber, fuel, disease
• Advances in technology
• Will humans exceed Earth’s carrying capacity?
• How do we know if we have?
• What should we do about it?
• What are the moral, religious, and personal freedom
implications?
WHERE ARE WE HEADED?
U.N. world
population
projection:
based on
women having
an average of
2.5 (high), 2.0
(medium), or 1.5
(low) children
FACTORS THAT DRIVE HUMAN
POPULATION GROWTH
• Demography – the study of human population
trends (demographer – scientists in this field)
• Crude birth rate = number per 1,000 per year
• Crude death rate = number per 1,000 per year
• I = immigration (movement in)
• E = emigration (movement out)
• Global pop growth rate = CBR – CDR
10
• Nation pop growth rate = [CBR + I] – [CDR + E]
10
SOME COMPARISONS
Average
crude death
(blue) and
birth (yellow)
rates for
various
groupings of
countries in
2006
DOUBLING TIME
• The number of years it takes for a population to
double
• Assumes that the growth rate is constant
• Formula called the rule of 70
• Doubling time (in years) =
70
growth rate
• Example:
Population growth rate of 2% will double in 35 years:
70/2 = 35
FERTILITY
• Total fertility rate
• Estimate of the average number of children for each
woman during her childbearing years
• Not measured per 1,000 – is a measure per woman
• In 2008 in the, U.S. TFR = 2.1
• Replacement-level fertility
• The TFR needed to offset the average number of deaths in
a population so that the current population size remains
stable
• This number is typically just over 2
• This also depends on rates of pre-reproductive mortality –
death before a person has children – this depends on a
country’s economic status
UNITED STATES
BIRTH RATES IN THE U.S. 1910 - 2006
FACTORS AFFECTING BIRTH RATES
•
•
•
•
•
•
•
•
The cost of raising and educating children
Availability of pensions
Urbanization
Education and employment opportunities
Infant deaths
Marriage age
Availability of contraception and abortion
Religious beliefs, traditions, and cultural norms
FACTORS AFFECTING DEATH RATES
• Death rates have declined due to:
•
•
•
•
Increased food supplies and better nutrition
Advances in medicine
Improved sanitation and personal hygiene
Safer water supplies
• U.S. infant mortality is higher than it could be
(ranked 46th world-wide) due to:
• Inadequate pre- and post-natal care for poor
• Drug addiction
• High teenage birth rate
DEVELOPED VS. DEVELOPING
COUNTRIES
• Developed countries – those with relatively high
levels of industrialization and income
• Example: U.S.
•
•
•
•
Typically have replacement-level fertility of 2.1
TFR = 2.1  population is stable
TFR < 2.1  population likely to decrease
TFR > 2.1  population likely to increase
• Developing countries – those with relatively low
levels of industrialization and incomes of < $3 per
person per day
• Example: India, China
DEVELOPING COUNTRIES
• China is the largest country – has taken drastic
population control measures
• By 2050 India is predicted to pass China. Pakistan is
projected to become 3rd, with Iran and Ethiopia
following
• Russia is losing 600,000 people/year after being the
4th largest country in 1950 – due to environmental
pollution, hyperinflation, crime, corruption, disease,
despair
EFFORTS TO SLOW POPULATION
GROWTH
Governments may try these tactics:
1. Raising taxes
2. Charging other fees
3. Eliminating income tax deductions for a couple’s third child
4. Loss of health-care benefits, food allotments, job options
• In China, couples who pledge to have no more than one child
receive:
1. Extra food
2. Larger pensions
3. Better housing
4. Free medical care
5. Salary bonuses
6. Free school tuition for their one child
7. Preferential treatment in employment when their child enters
the job market
CHINA
• Currently TFR = 1.6
• Has moved 300 million people out of poverty
• Problems:
• Strong male preference has lead to gender imbalance
• Average population age is increasing
• Not enough resources to support current population
INDIA
• Family planning program has basically failed due
to:
•
•
•
•
•
•
Poor planning
Bureaucratic inefficiency
Low status of women
Extreme poverty
Lack of administrative financial support
Disagreement over the best ways to slow population growth
THE BEST WAY TO SLOW POPULATION
GROWTH
• A combination approach works best:
1. Investing in family planning
2. Reducing poverty
3. Elevating the status of women – especially
educational opportunities
LIFE EXPECTANCY
• The average number of years an infant born in a
particular year in a particular country can be
expected to live – influenced by availability of
health care, access to good nutrition, exposure to
pollutants
• Usually expressed in 3 ways:
• Overall (2008 - U.S. 78)
• Men (2008 – U.S. 75)
• Women (2008 – U.S. 81)
• Men usually have higher death rates:
• Biological factors, greater workplace dangers, more
hazardous lifestyle choices, more likely to die in wars
INFANT AND CHILD MORTALITY
• Infant – deaths under age 1 per 1,000 live births
• Child – deaths under age 5 per 1,000 live births
• Sometimes the overall rates for a country vary
widely from those for a segment of the population:
• Infant mortality in U.S. = 6.6
• U.S. African Americans = 13.6
• U.S. Native Americans = 8.1
• Related to socioeconomic status and varying
access to adequate nutrition and health care
• An issue of environmental justice (Ch. 20)
AGING AND DISEASE
• Disease is an important regulator of human
population
• Infectious disease are the 2nd biggest killer
worldwide after heart disease
• Tuberculosis and malaria have been biggest portion
of this in the past
• Today, HIV is #1
• HIV disproportionately infects people age 15-49 and
so has a very disruptive impact on society
AGE STRUCTURE
• Visual representation of ages within a population
• Males on one side, females on the other
• Each bar = 5 year age group
• Three categories:
1. Pyramid – larger younger group; population will
continue to grow due to population momentum;
typical of developing countries; Venezuela, India
2. Column – little differences in age groups; slow or
no growth rate; U.S., Australia
3. Inverted pyramid – larger older group; population
is actually in decline; Italy, Germany, Russia
EXAMPLES
DEMOGRAPHIC TRANSITION
• Four-phase process of population and economic
development as a country moves from subsistence economy
to industrialization
• Phase 1 – pre-modernization; slow population growth rate
• High death rates offset high birth rates
• Phase 2 – beginning modernization; rapid population growth
rate
• Death rates decline due to better sanitation and health
care but birth rate remains high
• Phase 3 – stable population growth
• Birth rate slows
• Phase 4 – declining population
• More elderly than young people
POPULATION SIZE AND CONSUMPTION
• Ecological footprint – the amount of resources a
person uses by eating, drinking, generating waste,
and consuming products
• 1/5th of the human population lives in developed
countries but they consume more than ½ of the
world’s energy and resources
• The U.S. has the largest ecological footprint of any
country
• IPAT equation – an estimate of impact of humans
• Impact = population x affluence x technology
COMPARISON OF FOOTPRINTS
WHAT GOES INTO THIS?
SUSTAINABILITY
• Meeting the essential needs of people in the
present without compromising the ability of future
generations to meet their needs
• Strives to improve standards of living without
causing additional environmental harm
• How? Some ideas:
• Slower human population growth
• Understanding of the connections between economic
growth and environmental challenges
• This is a very important APES concept! Make sure
you ‘get’ it!