Limits to Growth / Human Population Ch 5.2 / Ch 5.3

Limiting Factors Limiting Factors: factors that control population growth Density-Dependent: operates when population density reaches a certain level Examples: competition, herbivory, predation, disease, parasitism, and stress from overcrowding Density-Independent: effects population regardless of density Examples: hurricanes, droughts, floods (natural disasters)

Density-dependent Factors Competition individuals compete for essential resources Predation / Herbivory Predator v. Prey Parasitism large population = more chance for disease to spread Overcrowding Stress for space causes individuals to fight → causes stress → weaken the body for diseases

Human Population Growth Beginning: Population grew slowly Causes: harsh environment, scarce food, predators and diseases were common Then: Population is growing rapidly (exponential) Causes: sanitation, improved nutrition, medicine, improved healthcare Now: Population is still growing but at a slower pace

Comparing Population Growth Demography: examines characteristics of human population and attempt to explain how populations change over time Birth rates Death rates Age structure

Demographic Transition Stage I: birth rates and death rates are high Stage II: nutrition, sanitation, medicine lead to low death rates; birth rates remain high Stage III: levels of education and standards of living rise so birth rates fall