Ch. 2 The Demographic Transition and Population Pyramids

The Demographic Transition To understand changes in population geographers classify regions using the Demographic Transition. The process of change in a society’s population from a condition of high crude birth and death rates and low rate of natural increase to a condition of low crude birth and death rates, low rate of natural increase and a higher total population.

Four Stages of the Demographic Transition Stage 1 – Low Growth CBR and CDR varied considerably from one year to the next but were at very high levels. NIR was essentially zero. During this stage people depended on hunting and gathering until 8000 B.C. when the agricultural revolution gave people more stable sources of food. But food supplies were still unpredictable and war/disease also took their toll in stage 1 societies – thus low growth occurred (about half a million people). THERE ARE NO COUNTRIES IN STAGE 1 TODAY!

Draw and label a Stage 1 on your notebook paper

Four Stages of the Demographic Transition Stage 2 – High Growth Around A.D. 1750 the world’s population suddenly began to grow 10 times faster than in the past. High growth occurs because the CDR drops and while the CBR remains roughly the same, thus leading to a high NIR. Countries entered stage 2 as a result of the Industrial Revolution (began in England and spread to Europe/North America). Industrial Revolution led to increases in wealth = increases in health. Greater improvements to agriculture, sanitation – water and sewage. Africa, Asia and Latin America did not enter stage 2 until the 1950’s. Countries in Africa, Asia, and Latin America moved into stage 2 during the second half of the 20th century due to the medical revolution. Diffusion of medical technology from Europe and North America impacted CDR.

Draw and label a Stage 2 on your notebook paper

Four Stages of the Demographic Transition Stage 3 – Moderate Growth A country moves into stage 3 when the CBR begins to drop sharply. Population continues to grow because CBR is still higher than CDR but the NIR is lower than stage 2 countries. European and North American countries moved into stage 3 during the first half of the 20th century and recently most countries in Asia and Latin America have moved into to stage 3. Most African countries remain in stage 2. Societies enter stage 3 when people CHOOSE to have fewer children = decline in IMR, economic changes from rural to urban. Why is choosing so important to get into this stage? Think about China? USA? Why are they different?

Draw and label a Stage 3 on your notebook paper

Four Stages of the Demographic Transition Stage 4 – Low Growth Countries reach stage 4 when CBR declines to the point where it equals CDR, and the natural increase rate approaches zero. Stage 4 countries enter zero population growth (ZPG). TFR of approximately 2.1 produces ZPG. Women in stage 4 countries enter the workforce, creating changes in lifestyle leading to smaller families. Also, government policies of former communist countries led to lower CBR and higher CDR’s. Negative NIR rates mean that CDR exceeds CBR and if it continues may lead to a future stage 5 of the Demographic Transition. Read pg. 57 on Stage 4 to better understand the drop in family size Why is USA not at ZPG?

Draw and label a Stage 4 on your notebook paper

Demographic Transition in England 1750-1880 Industrial Revolution 1880-1970s Choose to Have less children Invasion and the Plague England’s pop. Growth is due to immigration from former colonies

On a brand new page copy the following two slides of information on pop. Pyramids… Population Pyramids A country’s stage of the demographic transition gives it a distinctive population structure. Pyramids are bar graphs that display a country’s population in terms of age and gender. Pyramids explain age distribution and sex ratios.

Population Pyramids Dependency ratio – the number of people who are too young or too old to work, compared to the number of people in their productive years. Why would geographers study this? Sex ratio – number of males per hundred females.

Stage 2 – Babies out the Wahzoo! Sketch this pop pyramid onto the Stage 2 page of Notes already started. Be sure to include the saying at the bottom! Stage 2 – Babies out the Wahzoo!

Sketch this pop pyramid onto the Stage 3 page of Notes already started. Be sure to include the saying at the bottom! Stage 3 – In between!

Sketch this pop pyramid onto the Stage 4 page of Notes already started. Be sure to include the saying at the bottom! Stage 4 – Babies no more!