How has human populationgrown? Slowly over time Scarce food and incurable disease Death rate high Families had many childern 500 years ago Rapid growth Why? Agriculture, industrial; revolution, better food supply, shipping methods improved, improved sanitation, healthcare, improved medicine Led to expanded human growth
Science Behind HumanPopulation Thomas Malthus English Economist Human population cannont grow exponentially Limits: Famine, disease, war
Demography Scientific study of human population Study a variety of social and economic factors that effect human population Examines characteristics of human population and attempts to explain how and why human population changes over time
Things that help predict different population growth rates Birth rate Death rate Age structure
Hypothesis These countries have completed a “demographic transition”, a dramatic change in birth and death rates Historically: humans have high birth and death rates 500 years ago a change began: High birth rate and LOW death rate Because of better conditions of living
Demographic Transition Dramatic change in birth rates and death rates Low Death rate, High Birth rate From 1760 to 1910 Society modernizes Increase level of education Raise standars of living Families have fewer children Birth rate decreases Population growth slows Demographic 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 Structure Population depends partly on how many people of different ages make up a population Age-structure diagrams Population profiles used to predict future population growth Show population of a country broken down by gender and age group
Age structure in US Equal # of people in each age group Slow 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 Population India Compulsory sterilization China Family planning program Benefits and bonuses Forced abortions
Predicting Future Population Growth Many factors Age structure of countries Prevalence of life threatening diseases By 2050 9 billion Growth 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 Environment Global economy Other ecologists predict that science, technology, and changes in society will control those negative impacts on economy and environment
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