Ch 5.
Human Population
How has human population grown?Slowly over time
Scarce food and incurable diseaseDeath rate highFamilies had many childern
500 years agoRaid growthWhy?
Agriculture, industrial; revolution, better food supply, shipping methods improved, improved sanitation, healthcare, improved medicine
Led to expanded human growth
Science Behind Human PopulationThomas Malthus
English EconomistHuman population cannont grow
exponentiallyLimits: Famine, disease, war
DemographyScientific study of human populationStudy a variety of social and economic
factors that effect human populationExamines characteristics of human
population and attempts to explain how and why human population changes over time
Things that help predict different population growth ratesBirth rate Death rateAge structure
HypothesisThese countries have completed a
“demographic transition”, a dramatic change in birth and death ratesHistorically: humans have high birth and
death ratesNow: High birth rate and LOW death rate
Because of better conditions of living
Demographic TransitionDramatic change in birth rates and death ratesLow Death rate, High Birth rate
From 1760 to 1910Society modernizes
Increase level of educationRaise standars of livingFamilies have fewer children
Birth rate decreasesPopulation growth slowsDemographic transition complete when:
Birth rate falls to meet death rate and population growth stops
Only complete in a few countries India and China high birth rate
Age StructurePopulation depends partly on how many
people of different ages make up a population
Age-structure diagramsPopulation profiles used to predict future
population growthShow population of a country broken down
by gender and age group
Age structure in USEqual # of people in each age groupSlow and steady growth rate for near future
Age Structure in Nigeria
• More young children than teenagers• More teenagers than adults• Population will double in 30 years
Controlling Human PopulationIndia
Compulsory sterilizationChina
Family planning programBenefits and bonuses
Forced abortions
Predicting Future Population GrowthMany factors
Age structure of countriesPrevalence of life threatening diseases
By 20509 billionGrowth will level off or decrease if countries
growing rapidly go through demographic transition
Lower growth rate means population growth is slowing by it is STILL growing
How does this effect environment?Ecologists predict that if this growth does not
slow even more there will be Serious damage to EnvironmentGlobal economy
Other ecologists predict that science, technology, and changes in society will control those negative impacts on economy and environment