Human Population

Human Population Ch 35.3

How has human population grown? Slowly over time Scarce food and incurable disease Death rate high Families had many childern

500 years ago Raid growth Why?  Agriculture, industrial; revolution, better food supply, shipping methods improved, improved sanitation, healthcare, improved medicine  Led to expanded human growth

Science Behind Human Population 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 Now: 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