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| 1. |
Human
population size is ultimately limited by food
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supply
and/or other factors such as disease.
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| 2. |
Food
supply is increased by increasing inputs of
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capital—e.g.,
machinery, fertilizer.
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| 3. |
More
capital requires more resources, but material
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and
energetic resources have available limits that
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place
practical constraints on human economies.
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| 4. |
Essential
resources are not replaceable—e.g., water,
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chemical
elements used by living cells.
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| 5. |
Pollution
interferes with the growth of food and
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population.
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