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History of Human Population Growth. Carrying Capacity. The maximum number of people that can be supported by an environment, given the technology which exists at that time Earth’s human carrying capacity has increased numerous times throughout history. Stages of Human Population Growth.
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Carrying Capacity • The maximum number of people that can be supported by an environment, given the technology which exists at that time • Earth’s human carrying capacity has increased numerous times throughout history
Stages of Human Population Growth • Stage 1: Pre-historic hunter-gatherers • Stage 2: Agricultural Revolution • Stage 3: Industrial Revolution • Stage 4: Green Revolution
Stage 1: Prehistoric Humans • Humans survive as hunter-gatherers • Nomadic, follow the source of food • Unreliable food supply = minimal population growth • When times are good, food is plentiful, population increases • Increased population puts strain on the food supply, population decreases • Low carrying capacity, human population is low ten’s of millions
Stage 2: Agricultural Revolution (10 000 years ago) • Domesticated crops and animals • Food supply is stable, and increasing • Population increasing, development of towns/cities • Leads to food surplus • Surplus of food allows for trade, beginnings of an economy • Food Surplus allows more complex society • Creation of new jobs, art, food and culture • Not everyone needs to be growing food • Carrying capacity increases, population increases (100 million)
Stage 3: Industrial Revolution 1700’s • Technological innovations limited by “energy need” • Human and animal labour used for manufacturing/agriculture • Introduce steam, wind, coal, fossil fuel energy • Machines improve productivity across the board • More food can be produced, more goods can be made • Fewer workers needed on farms, move to cities, work in factories • Carrying capacity increased again, world population around 700 million
Stage 4: Green Revolution 1940-1970 • Huge increase in food production around the world • Synthetic fertilizers, chemical pesticides, genetic manipulation of crop species • High Yielding Varieties (HYV’s) of wheat, rice and corn • More resistant to drought, temperature, insects • Carrying capacity increased • Population doubles from 2 billion (1940) to 4 billion (1970)