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Section #1: Studying Human Populations

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Presentation on theme: "Section #1: Studying Human Populations"— Presentation transcript:

1 Section #1: Studying Human Populations

2 China Beach

3 Demography: the study of human populations
looks at the historical size (the past population), economics, social structure, & make-up (race, religion, gender, etc.) usually done by country

4 Developed vs. Developing
demographers usually group countries based on similar population trends developed countries tend to grow more slowly than developing countries

5 Exponential Human Growth
Growth rate increased rapidly each decade since the 1800s Mainly from increases in food production & improvements with hygiene (industrial & scientific revolutions) Earth can’t sustain this growth much longer

6 Population Pyramids

7 Forecasting Population Size
Will our area need more schools or more retirement communities in the next 25 years? Will more people move in creating a greater demand for roads & utilities?

8 Age Structure predictions are made on the distribution of ages in a specific population at a certain time graphed in a population pyramid that looks like a two-sided bar graph

9 Population Pyramids

10 Survivorship the % of members of a group that are likely to survive to any given age demographers predict this by studying a group of people born at the same time & looks at when each person dies

11 Survivorship Curves Type I Curve = most members in that population survive to be very old Type II = similar death rate at all ages (some die younger, others older) Type III Curve = many children die

12 Survivorship Curves

13 Fertility Rates the # of babies born each year per 1000 women in a population demographers also look at total fertility rates = the average # of children a woman gives birth to in her lifetime

14 Historical Total Fertility Rates for the U.S.

15 Replacement Level the average # of children each parent must have in order to “replace” themselves in the population ≈2.1 (slightly more than 2) because not all children born will survive & reproduce

16 Migration even in the event that total fertility rates drop below the replacement level (like they did in the U.S. in 1972), a population can still continue to grow from the increased movement of individuals from another area

17 Immigration vs. Emigration
immigration = movement into an area emigration = movement out of an area

18 Declining Death Rates adequate food clean water safe sewage disposal
vaccines improved healthcare sanitation

19 Life Expectancy the average # of years a person is likely to live
most affected by infant mortality 1900 – worldwide life expectancy was 40 years & infant mortality was very high 2000 – worldwide life expectancy is now 67 years & infant mortality much lower

20 Life Expectancy

21 Infant Mortality depends on a parent’s access to education, food, fuel, & clean water expensive medical care is not necessary – babies that are well fed, kept clean & warm have a better chance of surviving

22 Demographic Transition
a model that shows changes in a developed country’s population question? How can a population quadruple in a single century & then stop growing? theory – industrial development causes economic & social progress that affects population growth rates

23 Stages of Transition pre-industrial conditions (birth & death rates high, population stable) population explosion (death rates decline while birth rates remain high) population growth slows (birth rates decrease to match the death rate) & population size stabilizes population size begins to decrease as the birth rate drops below the replacement level

24 Why are Birth Rates Declining?
increasing education of women increasing the economic independence of women when women learn how to help their babies survive, they do not need to bear as many + large families may be a financial burden rather than an asset

25 Four Stages of Transition

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