The study of populations

Developed Countries 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 -

Population growth rates increased during each decade Due to increases in food productions and improvements in hygiene with industrial/scientific revolutions.

Demographers looks at these properties to predict population changes: 1. Age Structure 2. Survivorship 3.Fertility Rates 4.Migration

Age Structure Diagram Age Structure Diagram = Type of double sided bar graph Typically the more young people than older people leads to an increase in population size.

= 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.

= 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)

= “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!

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 food 2.Access to clean water 3.Safe sewage disposal

Look at the chart on page 238 Figure 7 What kind of regions have the highest life expectancies? MORE DEVELOPED COUNTRIES

“ 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 ” I N 1900, WORLD WIDE LIFE EXPECTANCY WAS ABOUT 40 YEARS AND THE INFANT MORTALITY RATE WAS VERY HIGH. B Y 2000, THE RATE OF INFANT MORTALITY WAS LESS THAN 1/3 OF THE RATE IN 1900 L IFE E XPECTANCY A VERAGE : A VERAGE = 67 YO D EVELOPED COUNTRIES = 80 YO

Most affected by parents’ access to: 1.education 2.Fuel 3.Food 4.Clean water *notice it is NOT health care!

…CONTAGIOUS DISEASES! Tuberculosis AIDS *South Africa’s life expectancy has been reduced due to an AIDS epidemic

“A model that describes how economic and social changes affect population growth rates.” It has 4 stages:

Stage 1 “ Preindustrial” Birth and death rates are about equal Most of the world was here until 1700 when stage 2 hit.

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!

Birth rate decreases Populations begin to stabilize But the population has quadrupled in size due to the transition.

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.

Factors that lead to decline in death rates: 1. increasing education 2. 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

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!

Developed: 1.6 children per woman Developing Countries: 3.1 Children per woman