Farming and population density
From Harvesting the Biosphere:
Half a million years ago, there were between 15,000 - 125,000 people, total. Today there are about 8bn. What changed? How we farm.
| min | max | |
|---|---|---|
| Foraging | 0.01 | 1 |
| Pastoralism | 1 | 2 |
| Shifting Cultivation | 20 | 30 |
| Traditional Farming | 100 | 400 |
| Modern Farming | 400 | 1400 |
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During the late Paleolithic, the climate was too cold and C02 levels too low for agriculture to develop.
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As the climate warmed in the Neolithic, first pastoralism, and then agriculture took off.
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The shift from foraging to pastoralism meant a 100x increase in the number of people that could be supported for the same amount of land.
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Pastoralism also unlocked previously inaccessible energy stored in grassland. By grazing animals, then eating them, people could survive in places too arid for cropping.
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Shifting cultivation produced between 6-30x the energy expended doing the farming.
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Traditional agriculture hit its limit after 1850. It could not produce enough food for expanding populations, rapid industrialization and urbanization.
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Before the discovery of the Haber process, soil replentishment was the major bottleneck. Nitrogen and phosphorus depletion in the soil limited crop yield and how often you could grow.
- Slash and burn agriculture and crop rotation provided limited workarounds.
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Modern agriculture (1900s-1950) has ratcheted up the people-per-land ratio even more. The Green Revolution, synthetic NPK fertilizer, industrial automation and new crop varieties are the driving forces. There are now 7.4bn of us.
Related: fundamental needs.