• Exam– Next Friday (Feb 6)– 1 essay, 50 multiple-choice, T/F, matching– #2 pencil– Study questions available on the class web site

• Review 3:30 Wed (Feb 4) in ??

Some Topics Discussed

• Population growth

• Limits to growth

• Human demography

• Demographic transition

• Family planning and fertility control

• The future of human populations

ESC110 Chapter 4. Human Populations

Population Growth

World population now over 6 billion

• World pop:World pop: – 2003 = 6,271,470,983– 2004 = 6,345,338,406

• US pop:US pop:– 2003 = 290,131,722– 2004 = 292,484,293

http://www.census.gov/main/www/popclock.html

Current Birth and Death Rates

• Every second: 4 or 5 children are born, while 2 other people die

• Net gain: 2.5 humans added to the world population every second

• 78 million added every year

Effect of Birth Rate and Death Rate on Population Size

Human Population Levels Throughout History

Growth to a Stable PopulationGrowth to a Stable Population

Overshoots and Diebacks

Basic Causes of

Environmental Problems

(McKinney & Schoch)

P x A x TP x A x TEnvironmental Environmental Impact =Impact =

P = number of peopleA = affluence or average resource-use per personT = technology or the beneficial & harmful environmental effects of the

technologies used to provide & consume each unit of resource

Projected Population Growth

Table 4.3

Limits to Growth

Varying Perspectives • Overpopulation causes resource depletion and

environmental degradation• Human ingenuity and technology will allow us

to overcome any problems - more people may be beneficial

• Resources are sufficient to meet everyone's needs - shortages are the result of greed, waste, and oppression

Decisions on how many children to have are influenced by many factors, including culture, religion, politics, need for old-age security, and immediate family finances.

Human Demography

• Demography - vital statistics about people, such as births and deaths

Two demographic worlds– Less-developed countries represent 80%

of the world population, but more than 90% of projected growth

– Richer countries tend to have negative growth rates

By 2050, India will probably be the world’s most populous country.

World Population Density

Fertility and Birth Rates

• Fecundity - physical ability to reproduce• Fertility - the actual production of offspring• Crude birth rate - number of births per year

per thousand people• Total fertility rate - number of children born

to an average woman during her reproductive life

• Zero population growth (ZPG) - occurs when births + immigration just equal deaths + emigration

Regional Declines in Total Fertility Rates

As incomes rise, so does life expectancy.

Population Growth -Opposing Factors

Pronatalist pressures• Factors that increase people’s desires to have children

(eg, enjoy family, help earnings, high death rate, help when older, males valued, male pride, etc)

Birth reduction pressures• Factors that tend to reduce fertility (eg, educated

women & careers, higher family earnings, etc)

U.S. Birth Rates: 1910-2001

Demographic TransitionDemographic Transition AccompanyingEconomic and Social Development

Demographic Transition

• Optimistic view - world population will stabilize during this century

• Pessimistic view - poorer countries of the world are caught in a "demographic trap" - helping poor countries will only further threaten the earth's resources

• Social justice view - overpopulation due to a lack of justice, not resources

Infant Mortality and Women's Rights

Birth Control

Methods

Family Planning

The Future of Human Populations

U.N. Projections

Fig. 4.13

Summary:

• Population Doubling Times• Role of Technology • Two Demographic Worlds• Fertility and Birth Rates• Mortality and Death Rates• Population Growth Factors• Demographic Transition• Future of Population Growth