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Population. Key Issue 3. Deep Thought. What can be determined about the following places based on their population pyramids?. Geographic Models – always remember models are just models – not reality. GEOGRAPHIC MODELS. First, Models are JUST models
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Population Key Issue 3
Deep Thought • What can be determined about the following places based on their population pyramids?
Geographic Models – always remember models are just models – not reality
GEOGRAPHIC MODELS • First, Models are JUST models • Discuss the purpose of the model. What does the model do? • Basic assumptions of the model • Description and analysis of the model (zones) • Usefulness and/or applications of the model
Demographic Transition Model • 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. • Barring catastrophe, the transition is irreversible!
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). • No country is still in Stage 1
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.
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.
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.
Do the DEMOGRAPHIC TRANSITION… Explain each stage as a class • Based on Western Europe’s experiences • Stage 3 - personal choices – most critical stage • Stage 4 – social customs - women
Tell us more, Hans! • Let’s let Hans help explain - 15 min. • http://www.ted.com/talks/hans_rosling_the_good_news_of_the_decade.html?utm_source=newsletter_weekly_2010-10-12&utm_campaign=newsletter_weekly&utm_medium=email