Chapter 6: The Human Population and Its Impact

How Many People Can the Earth Support?

Natural Capital Degradation
  • Reduction of biodiversity
  • Increase NPP use
  • Elimination of natural predators
  • Interfering with biochemical cycling
  • Relying on fossil fuels
Human Population Growth Continues but It Is Unevenly Distributed
  • Cultural carrying capacity: the number and type of a given species that people will tolerate over time

What Factors Influence the Size of the Human Population?

The Human Population Can Grow, Decline, or Remain Fairly Stable
  • Population change: (births + immigration) – (deaths + emigration)
  • Crude birth rate: The number of live birth's per 1,000 people in a population in a given year
  • Crude death rate: The number of deaths per 1,000 people in a population in a given year
Women Having Fewer Babies but Not Few Enough to Stabilize the World’s Population
  • Fertility rate: Number of children born to a woman during her lifetime
  • Replacement-level fertility rate: The average number of children a couple must have to replace themselves   * 2.1 in developed countries   * up to 2.4 in developing countries   * Not immediate so many are younger than 15 years old
  • Total Fertility Rate (TFR): The average number of children born to women in a population during their reproductive years.   * Plays a role in determining population size
Factors That Affect Birth and Fertility Rates
  • Children might be a part of the labor force
  • Cost of raising children
  • Education and employment of women are slowly increasing
  • Availability of abortions
  • Religious or cultural beliefs
  • Availability of birth control
Factors That Affect Death Rates
  • Life expectancy: The average number that an individual is likely to live   * Global life expectancy from 48 in 1955 to 69 in 2010
  • Infant mortality rate: Number of live births that die in the first year   * A strong indication of the quality of life in the area
  • Longer lives because…   * Increased food supply   * More nutritions   * Available medical resources   * Improvements in sanitization

How Does a Population’s Age Structure Affect Its Growth or Decline?

A Population’s Age Structure Helps Us Make Projections
  • Age Structure Categories:   * Prepreproductive age (0-14)   * Reproductive ages (15-44)   * Postreproductive ages (45 and older)

 The 4 different age structure graphs

Some Problems With Rapid Population Decline
  • Threaten economic growth
  • labor shortage
  • Fewer business formations
  • Retirement age increases
  • Pensions can be cut

How Can We Slow Human Population Growth?

As Countries Develop, Their Populations Tend to Grow More Slowly
  • Demographic transition: First death rate declines and then the birth rate declines.
  • Four Stages   * Preindustrial: The population grows slowly and has a high death and birth rate.   * Transitional: The population grows rapidly and the birth rate is high. Death rate drops.   * Industrial: Population growth slows as both birth and death rates drop because of improved food production, health, and education   * Postindustrial: Population growth levels off and then declines as birth rates equal and the fall below death rates
Women
  • Do most of the housework and care for children
  • Unpaid health care
  • Discriminated against legally and religiously
  • Women make up 64% of the 800 million illiterate adults   * Illiterate women TFR→ 5-7 Children   * Literate women TFR→ 2 or fewer children
  • Family Planning: Provides educational and clinical services that help couples choose how many children they want to have and when to have them

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