history of the human population. in 1838, the ideas of malthus greatly impressed a young naturalist...
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History of the Human Population
In 1838, the ideas of Malthus greatly impressed a young naturalist named Charles Darwin. Malthus’s idea that
populations tend to outgrow their resources became a major point in Darwin’s theory of
evolution by natural selection. According to Darwin’s 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.
1. Why do many organisms produce more offspring than can survive?
2. According to Darwin, the individuals that survive have what?
1. Why do many organisms produce more offspring than can survive?
To ensure survival of a few
2. According to Darwin, the individuals that survive have what?
Favorable traits
Thomas Malthus1798
• Population growth is not always desirable
• Population increases geometrically1,2,4,8,16,32
• Food supply increases arithmetically1,2,3,4,5
Human population increases at a faster rate than food supply!!!
This could lead to famine and war
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!!!
What was Malthus’ solution?
Reduce population
growth rate by:
–Later marriages
–Small families
Hunter-Gatherer
• Slow population growth
• Starvation, predation, disease- short lives
• High infant mortality rate
• Food storage– increase in population size
Agriculture
• Farming communites
• Increased and steady food supply– increase in human population
• Increase in standard of living- reduced mortality rates and increased life expectancy
Industrial
• Technological advances- increased food production and distribution
• Safer work environments
• Improvement in health care- germ theory
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
Declines in Growth Rate1. Disease: bubonic plague reduced
England’s population by ½
• Cholera, typhus, yellow fever, smallpox
• More common in cities
2. Famine- plant diseases
• Ex: potato blight in Ireland
3. War
1. What were Malthus’s 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?