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Transcript of The study of populations Developed Countries Developed Countries -Ex. United states -Have higher...
Ch 9 The Human Population
Demography• The study of populations
Demographics – into 2 categories
Developed Countries- Ex. United states- Have higher
average incomes- Slower population
growth- Diverse industrial
economies
Undeveloped Countries- Ex. South Africa- Have lower average
incomes- Simple and
agriculture-based economies
- Rapid population growth
-
Exponential Growth
• Population growth rates increased during each decade
• Due to increases in food productions and improvements in hygiene with industrial/scientific revolutions.
Age Structure Diagrams
Forecasting Population Size• Demographers
looks at these properties to predict population changes:
1. Age Structure2. Survivorship3. Fertility Rates4. Migration
1.Age Structure = the age distribution of ages in a specific population at a certain time. • Age Structure
Diagram = Type of double sided bar graph
• Typically the more young people than older people leads to an increase in population size.
2. Survivorship• = the percentage
of members of a group that are likely to survive to any given age.
• Demographers study groups of people born at the same time and notes when each person dies.
• Type I – Wealthy countries like Japan and Germany bc people live to old age.
• Type II – populations have similar death rate at all ages.
• Type III – Poor countries in which many children die early.
3. Fertility Rates• = the number of
babies born each year per 1,000 women in a population.
• Total fertility rate = average number of children a woman
gives birth to in her lifetime.- Replacement Level =
• Replacement Level = the average number of children each parent must have in order to “replace” themselves.
• The average is about 2.1 (since not all children will survive)
4. Migration• = “the movement of
individuals between areas” • Two types:• 1. Immigration –
movement into an area• 2. Emigration –
movement out of an area
• Quick check:The population of the U.S. and other developed countries might be DECREASING if not for which?
Immigration!
Declining Death Rates• The dramatic
increase in Earth’s human population in the last 200 years has happened because death rates have declined more rapidly than birth rates.
• Reasons:1. Access to
adequate food2. Access to
clean water3. Safe sewage
disposal
Question:
• Look at the chart on page 238 Figure 7
What kind of regions have the highest life expectancies?MORE DEVELOPED
COUNTRIES
Life Expectancy• “the average number
of years members of a population are expected to live”
• Most affected by:INFANT MORTALILTY RATE
= “THE DEATH RATES OF INFANTS LESS THAN 1 YEAR OLD”
IN 1900, WORLD WIDE LIFE EXPECTANCY WAS ABOUT 40 YEARS AND THE INFANT MORTALITY RATE WAS VERY HIGH. BY 2000, THE RATE OF INFANT MORTALITY WAS LESS THAN 1/3 OF THE RATE IN 1900
LIFE EXPECTANCY AVERAGE:
AVERAGE = 67 YODEVELOPED COUNTRIES = 80YO
Infant mortality rate• Most affected by
parents’ access to:1. education2. Fuel3. Food4. Clean water
*notice it is NOT health care!
New Threats to life expectancy:
…CONTAGIOUS DISEASES!
TuberculosisAIDS
*South Africa’s life expectancy has been reduceddue to an AIDS epidemic
What do we need for our populations?
The Demographic Transition
• “A model that describes how economic and social changes affect population growth rates.”
• It has 4 stages:
4 stages of Demographic Transition
Stage 1
• “Preindustrial”• Birth and death
rates are about equal• Most of the world
was here until 1700 when stage 2 hit.
Stage 2
A Population explosion occurs! (may double in ≥ 30 years)
• Death rates decline: due to hygiene, nutrition, and education improve.
Birth rates remain high, so the population grows quickly!
Stage 3
• Birth rate decreases
• Populations begin to stabilize
• But the population has quadrupled in size due to the transition.
Stage 4: “postindustrial”
• The birth rate drops below replacement level, so the size of the population begins to decrease.
• This has taken 1-3 generations to occur in a developed country.
Women and Fertility
• Factors that lead to decline in death rates:
1. increasing education2. economic independance
Education:• Educated women
KNOW they don’t need lots of kids in case a few will die.
• Family planning
$ brings freedom- Contribute to family- Spend less energy
bearing/caring for kids
Why large families?
Traditionally:• Some communities
children work• Kids take care of
elderly
Modernization:1. If women work, kids need daycare which is expensive, so less is better.2. Working creates PENSIONS so elderly support themselves.
This is lowering the birth rate!
Current Total fertility rates…
Developed:1.6 children per woman
Developing Countries:3.1 Children per woman