PowerPoint Presentation Chapter04

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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)
Click here for current US and World population
estimates -gt
http//www.census.gov/main/www/popclock.html
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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
famines, etc.
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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

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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) - births
  immigration 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
two decades. However, the policy is very
controversial.
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Death

• The death rate in most countries is one per
  person
• Crude death rate number of deaths/1000
• Less developed, over 20/1000
• Developed, about 10/1000
• Fewer deaths in rapid growth than in slow growth
• Most population growth over past 300 yrs due to
  falling mortality

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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
  (fewer workers compared to retirees)
• i.e., how many workers support children or
  retirees
• If current trends continue, by 2100 the median
  age in the U.S. will be 60.

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Age structure diagrams

• Shows the distribution by age of the females
  males in a population
• Age intervals generally broken into 5-year
  intervals

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Major age groups 0 15 yrs
pre-reproductive 15- 45 yrs reproductive 45
yrs post-reproductive
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Part 4 Population Growth -Opposing Factors

• Pronatalist pressures
• Factors that increase people's desires to have
  children (need for workers/care givers, tax
  breaks, societal pressure)
• Birth reduction pressures
• Factors that tend to reduce fertility (education,
  government controls)

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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 Accompanying Economic 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