History of the Human Population

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History of the Human Population
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• In 1838, the ideas of Malthus greatly impressed a
  young naturalist named Charles Darwin. Malthuss
  idea that populations tend to outgrow their
  resources became a major point in Darwins theory
  of evolution by natural selection. According to
  Darwins theory, organisms produce more offspring
  than can survive. Within the population there are
  a variety of traits. Those individuals with the
  most favorable traits will survive and pass those
  traits to their offspring. Over many generations,
  favorable traits accumulate in the population,
  resulting in evolution.

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1. Why do many organisms produce more offspring than
   can survive?
2. According to Darwin, the individuals that survive
   have what?

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• Why do many organisms produce more offspring than
  can survive?
• To ensure survival of a few

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• 2. According to Darwin, the individuals that
  survive have what?
• Favorable traits

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Thomas Malthus1798

• Population growth is not always desirable
• Population increases geometrically
• 1,2,4,8,16,32
• Food supply increases arithmetically
• 1,2,3,4,5
• Human population increases at a faster rate than
  food supply!!!
• This could lead to famine and war

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When will the population remain stable?

• When birth rate equals death rate!!!!
• Increased birth rates increase population size
• Decreased death rate increases population size
• If both are the same, the population should
  remain stable!!!

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What was Malthus solution?

• Reduce population growth rate by
• Later marriages
• Small families

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Hunter-Gatherer

• Slow population growth
• Starvation, predation, disease- short lives
• High infant mortality rate
• Food storage increase in population size

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Agriculture

• Farming communites
• Increased and steady food supply increase in
  human population
• Increase in standard of living- reduced mortality
  rates and increased life expectancy

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Industrial

• Technological advances- increased food production
  and distribution
• Safer work environments
• Improvement in health care- germ theory

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Germ Theory

• Bacteria and other microorganisms are responsible
  for many diseases
• Led to an increase in
• Sterile surgery
• Better personal hygiene
• Water treatment
• Biomedical Revolution- increase in vaccines and
  antibiotics
• This all led to an increase in population

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Declines in Growth Rate

• Disease bubonic plague reduced Englands
  population by ½
• Cholera, typhus, yellow fever, smallpox
• More common in cities
• Famine- plant diseases
• Ex potato blight in Ireland
• War

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1. What were Malthuss views about population growth
   vs. food supply growth?
2. What two rates affect overall population growth?
   Explain.
3. What event marked the second period of major
   population growth? How did this event influence
   population growth?
4. What era began about 300 years ago and also
   brought about major population growth? Explain
   how.
5. What is the germ theory?
6. How has the germ theory helped to contribute to
   population growth?
7. What are some contributing factors to declines in
   growth rate?