The study of the human population World Demography The study of the human population

Objectives Describe how size and growth rate of human pop has changed in the past 200 years Define 4 properties that are used to predict population sizes Describe 4 stages of demographic transition Explain why different countries may be at different stages of demographic transition Make predictions about population trends

Populations The study of human populations has its own term: Demography Demographers study many factors of a population to predict its future size One factor is whether the country is developed or developing.

Do you recall… Lower average incomes Higher average incomes Developing Countries Developed Countries Lower average incomes simple/farm-based economies Rapid population growth Higher average incomes Diverse/industrial economies Slower population growth

Forecasting Population Size There are 4 properties we can use to predict changes to a population

1. Age Structure Definition: the distribution of ages in a specific population at a certain time.

Q: What will happen to Scotland’s population in 20 years? Will they need more schools? More nursing homes? More room in cemetaries?

2. Survivorship Definition: the percentage of group members that are likely to survive to a given age. Type I: Wealthy, developed nations; populations are healthy and many live to old age Type II: similar death rate at all ages Type III: poor populations; high infant/children mortality rate

3. Fertility Rate Definition: The number of babies born each year per 1,000 women

What would cause a change in number of babies born?

Fertility with replacement level The Replacement Level is the number of children that must be born to replace their parents. Which populations are shrinking? Which populations are still growing? Trick Question! None will grow! Trick question – none of the countries are reaching the replacement rate of 2.1 per year!

4. Migration Definition: The movement of individuals between areas. Immigration: movement coming into an area Emigration: movement coming out of an area

Natural Increase + Migration

Factors that change populations

Many historic factors have changed populations Industrial Revolution led to access to Food Clean water Safer work-places Advancements in medicine

Life Expectancy These historic factors changed our nation’s life expectancy Life expectancy is the average number of years people are likely to live.

The Demographic Transition An eventual change in population

Population Transition What causes a population to stop growing and start decreasing?

Population Transition Definition: a model that describes how economic and social changes affect population growth rates. Scientists base this on observations and statistical data of other factors. Demographic transition happens in 4 stages.

Stage 1: Preindustrial Condition Birth rate – high Death rate – high Population size is stable

Stage 2: Population explosion Birth rates – high Death rates – drop due to social improvements Population grows very fast

Stage 3: Birth Rate Drops Birth Rate – decreases Death rate – still low Population size stabilizes to steady

Stage 4: Transition Birth rate – drops below replacement level Death rate – still low Population size starts to decrease since not enough children are born to replace the older generations

What type of graph is this?