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Population Growth Movie notes

The Rule of 72

    72 ÷ growth rate = years to double
  • example: if a country's growth rate is 3%, the population will double in about 24 years
  • example: if a country's population doubles in 18 years, its growth rate is about 4%

Topic 1: A brief history of world population

  • Prior to 1750 CE, world population totals were less than 800 million (800,000,000)
  • Between 1750 and 1950, world population more than tripled to 2.5 billion (2,500,000,000)
  • Between 1950 and 1975, world population increased to 4 billion (4,000,000,000)
  • At present, world population is greater than 5.9 billion (5,900,000,000)
  • Before 1750, population increased by around 67,000 every year. World population increases by that number every 8 hours presently.
  • consider a graph of the history of world population

Topic 2: Doubling time

  • Doubling time = the amount of time it would take for a given population to double
  • In 1983, world population increased by around 2% per year
  • This translates into a doubling time of 35 years
  • Long doubling times (countries with low rates of growth) = Japan (100 years), the USA (88 years), China (50 years)
  • Short doubling times (countries with high rates of growth) = Nigeria, Brazil, Indonesia, India (35 years), Pakistan (22 years)

Topic 3: Mortality rate

  • Mortality rate = death rate
  • Mortality rates have been historically very high
  • Little effective medicine
  • Recent improvements in care have dramatically lowered mortality rates worldwide

Topic 4: Fertility rate

  • Fertility rate = birth rate
  • Several reasons for historically high rate
    • Desire for children to live to adulthood
    • Inexpensive source of labor
    • Children provide security for parents in old age
    • Desire to have sons
    • Social status is in some cases determined by family size
    • Encouraged by governments for security/pride issues
  • Main reason for low rates in North America/Western Europe: Economics

Topic 5: Movement and migration

  • Always changes population balances
  • Usually movement occurs because of positive attributes of a region; immigration in most cases improves the region further in economic and political terms

Topic 6: Age/sex ratio

  • The number of people of each given age group
  • If more than 35% of a country's population is under the age of 15, it is considered a young population
  • If more than 15% of a country's population is over the age of 65, it is considered an old population
  • Project on population pyramids

Topic 7: Resources and food

  • In 1983, a person starved to death every 8 seconds
  • Reasons for a lack of food:
    • There is only a finite amount of land that can be used for agriculture
    • Most useable agricultural land is already under plow
    • Agricultural and urban demands often center on the same lands (as cities grow, they take over farmland)

Topic 8: Pollution and pesticide

  • Can render land sterile and useless
  • Seeks into and contaminates water supplies
  • Results in strains of resistant insects and diseases
consider a graph of the history of world population