1 chapter 4 human populations. 2 chapter four - topics population growth limits to growth: some...

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Chapter 4 Human Populations

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Chapter Four - Topics

• Population growth

• Limits to growth: some opposing views

• Human demography

• Population growth: opposing factors

• Demographic transition

• Family planning and fertility control

• The future of human populations

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Part 1: Population Growth

World population now 6.47 billion (Oct 12, 2005)http://www.census.gov/main/www/popclock.htmlClick here for current US and World population estimates ->

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Current Birth and Death Rates

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

• Net gain: 2.3 humans added to the world population every second, 72 million added every year

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Human Population Levels Throughout History

ADD FIG. 4.2

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ADD TABLE 4.1

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Part 2: 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

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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.

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Part 3: Human Demography

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

• Two demographic worlds• Less-developed counties represent

80% of the world population, but more than 90% of projected growth

• Richer countries tend to have negative growth rates

http://www.thirdworldtraveler.com/Third_World/TW_definition_description.html

What a stupid term…click below for definition of "third", "second", and "first" worlds…

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

(297)

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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

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Regional Declines in Total Fertility Rates

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China's one-child-per-family policy decreased the country's fertility rate from 6 to 1.8 in twodecades. However, the policy is very controversial.

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As incomes rise, so does life expectancy.

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Living Longer: Demographic Implications

• A population growing by natural increase has more young people than does a stationary population.

• Dependency ratio - the number of nonworking individuals compared to working individuals - declining in countries such as the U.S. and Japan

• If current trends continue, by 2100 the median age in the U.S. will be 60.

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Part 4: Population Growth -Opposing Factors

Pronatalist pressures• Factors that increase people's desires to have

childrenBirth reduction pressures• Factors that tend to reduce fertility

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U.S. Birth Rates: 1910-2001

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Part 5: 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

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Demographic Transition AccompanyingEconomic and Social Development

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Fig. 4.13

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Infant Mortality and Women's Rights

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Part 7: The Future of Human Populations