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ESC110 Chapter 4. Human Populations Some Topics Discussed Population growth Limits to growth Human demography Demographic transition Family planning and fertility control The future of human populations
Population Growth World population now over 6 billion
World pop: 2003 = 6,271,470,983 2004 = 6,345,338,406 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 Population
Overshoots and Diebacks
Basic Causes of Environmental Problems
(McKinney & Schoch)
P x A x T Environmental Impact =
P = number of people A = affluence or average resource-use per person T = 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 Transition Accompanying Economic 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