December 2011
Human Population Growth:
Historical Perspective
 The human population has experienced exponential
growth over the past 200 years. Why?
 Expanded into diverse habitats and climate zones.
 Development of modern agriculture
 Modern sanitation and public health advances
 Development of antibiotics and vaccinations
 Harnessed concentrated sources of energy
The Bottom Line
 No population can continue to grow indefinitely.
 Degradation of natural systems and resources jeopardizes our ability to
sustain populations and build economies.
 Differential effect of developed vs. developing countries
 In 2006, developed countries added 1.2 million people
 Developing countries added 79.5 million people.
Population Growth Projections
By 2050, human
population is
projected to be
between 7.2 and
10.6 billion people.
97% of the growth
in developing
countries.
Factors Affecting Human Population Size
When births plus immigration exceed deaths plus
emigration, population increases; when the reverse is true,
population declines.
This is true of other species as well as humans.
Comparison of birth rates and death rates
Demographers use:
Birth rate or crude birth rate:
number of live births per 1,000
people in a population in a given
year (U.S. – 14.18)
Death rate or crude death rate:
number of deaths per 1,000
people in a population in a given
year (U.S. – 8.27)
Declining Population: Observing Fertility Rates
 Fertility – number of children born to a woman during
her lifetime.
 replacement –level fertility - number of children a couple
must bear to replace themselves

Typically between 2.1 and 2.5 children per couple
 Total fertility (TFR) – average number of children a woman
typically has during her reproductive years




Global average about 2.7
Developed countries about 1.6
 United States – 2.06
Developing countries about 2.9
Range according to CIA (0.91 in Macau and 7.68 in Niger)
Population Projections
Case Study:
Fertility and Birth Rates in the U.S.
Case Study:
Fertility and Birth Rates in the U.S.
 1900 – 76 million Americans
 Baby boom – post WWII – 1946 to 1964
 Birth rate up to 3.7 at one point
 Corresponding “baby bust” – 1964 to 1977
 Due to delayed marriage, contraceptive use, and abortion
 2007 – saw 300 millionth American
 56% growth due to birth rate, 44% due to immigration
 Immigration shift from Europe to Latin American/Southeast
Asia
 High per capita resource use
Case Study:
Fertility and Birth Rates in the U.S.
Case Study:
Fertility and Birth Rates in the U.S.
Think about how life has changed…
Tractor-plow, 1905
In the United States NOW…
In the United States in 1905…
 Three leading causes of death: heart
 Three leading causes of death: pneumonia,
disease, cancer, stroke
tuberculosis, and diarrhea
 Common path to becoming a physician
 90% of doctors had no college education
requires 8 years of college and 3-8 years of
 1 out 5 adults cannot read or write
internship and residency
 Average U.S. worker earns $200-$400 per
 99% literate
year
 Average U.S. worker earns $42,028 per
 Only 9,000 cars in the U.S. with 144 miles of
year (2005 figures according to Worldsalaries.com)
paved roads
 450 million cars in the U.S. with 5.7 million
 3 minute phone call cost $11
miles of paved roads
 30 people live in Las Vegas, NV
 3 minute phone call costs $0.51 (according
 Most women washed their hair once a
to Mr. Bromwell’s cell phone plan)
month
 567,641people live in Las Vegas, NV
 I would imagine hair washing is daily
among other things…
Factors Affecting Birth Rates and Fertility Rates










Importance of children as part of the labor force
Cost of raising and educating children
Availability of private and public pension systems
Urbanization
Educational and employment opportunities available for
women
Infant mortality rate
Average age at marriage (or first child)
Availability of legal abortions
Availability of reliable birth control methods
Religious beliefs, traditions and cultural norms
Factors Affecting Death Rates
 Availability of food supplies
 Nutrition quality of available food supplies
 Availability of medical care, immunization, and antibiotics
 Sanitation
 Safe drinking water supplies
 Civil, governmental, or societal unrest or disadvantage
 Infant mortality rate
Life Expectancy and Infant Mortality Rate
 Two useful indicators of overall health of a population:
 Life expectancy – average number of years a newborn
infant can expect to live
 Infant mortality rate – number of babies out of every
1,000 born who die before their first birthday
 Single best measure of a society’s quality
 Reflects overall nutrition and health care
Infant Mortality in the U.S.
 In U.S. approximately 6.3 deaths /
1,000 births



Higher than expected due to
inadequate health care for poor
women during pregnancy,
drug addiction among pregnant
women,
and a high birth rate among
teenagers.
 Immigration + emigration
 Since 1820, U.S. admitted
twice as many immigrants as
all other nations combined!
 Legal vs. illegal immigration
 Racial/ethnic shift
 Pros
 ‘land of opportunity’
 Accept undesirable jobs,
pay taxes, create jobs
 Will replace aging boomer
generation
 Cons
 Increase countries
population, strain resources
 Magnet for world’s poor
Migration
Population Age Structure
 The distribution of males and
females in each age group in the
world’s population
 Age structure diagrams 
 Examine # of people in three age
categories
 prereproductive
 reproductive
 postreproductive
Population Age Structure Diagrams
The Baby-Boomers
 This generation makes up half of all adult workers and
dominates demand for goods and services.
Consequences of Population Decline
• Can threaten economic growth
• Less government revenues with fewer
workers
• Reduces availability of young people for
military service
• Less entrepreneurship and new
business formation
• Less likelihood for new technology
development
• Increasing public deficits to fund higher
pension and healthcare costs
Global Aging
The Demographic Transition
Percentage
of world
population
Population
20%
1.1 billion
1.3 billion
1.4 billion
1.6 billion
Population (2050)
(estimated)
Illiteracy (% of adults)
Total fertility rate
Infant mortality rate
47%
17%
36%
Population under age 15 (%)
Population growth rate (%)
20%
1.6%
0.6%
2.9 children per women (down from 5.3 in 1970)
1.6 children per women (down from 5.7 in 1972)
58
27
62 years
70 years
Life expectancy
Percentage living
below $2 per day
GDP PPP per capita
India
China
17%
80
47
$3,120
$5,890
Fig. 9-15, p. 186
References
Annual Estimates of the Resident Population for Incorporated Places in Nevada: April 1, 2000 to July 1, 2009" (CSV). United States
Census Bureau, Population Division. 2010-09. http://www.census.gov/popest/cities/tables/SUB-EST2009-04-32.csv. Retrieved
2010-11-16
“Infant Mortality Rate (per 1,000 live births)” Digital Image. Unnatural Causes. 2008. California Newsreel. 11 January, 2009.
http://www.unnaturalcauses.org/interactivities_04-6.php
Miller, G.T. Living in the Environment: 15th edition. Brooks/Cole, Belmont, CA, 2007.
“Population by region” Digital Image. The Sustainable Scale Project. 2003. The Santa-Barbara Family Foundation. 11 January, 2009.
http://www.sustainablescale.org/AreasofConcern/Population/PopulationandScale/QuickFacts.aspx
“Population growth” Digital Image. The Sustainable Scale Project. 2003. The Santa-Barbara Family Foundation. 11 January, 2009.
http://www.sustainablescale.org/AreasofConcern/Population/PopulationandScale/QuickFacts.aspx
"Rank Order - Total Fertility Rate." CIA - The World Fact Book. 18 Dec 2008. Central Intelligence Agency. 11 Jan 2009
<https://www.cia.gov/library/publications/the-world-factbook/rankorder/2127rank.html>.