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)

  

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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