Ch. 2 Key Issue 3

Why Is Population Increasing at Different Rates?

Demographic Transition Model• A model of population change where

high birth rates and death rates transition to low birth rates and death rates relative to (along with and due to) advances in medical technology, and economic and social development.

• A model is a simplified, general version of real events in order to facilitate understanding of a process

Demographic Transition Model

• Based on the shifts that Britain experienced– will other countries follow this same pattern?

• Population pyramids are graphical representations of the different stages (KI 3 pt 2)

Stage 1: Low Growth

• HIGH birth rates and death rates= low growth (low NIR)

• First Agricultural Revolution allowed population to swell

• No countries are in stage 1 anymore.

Stage 2: High Growth

• Move to stage 2 caused by severely declining death rates + birth rates remain high= lots of growth.– Industrial revolution (MDCs)– Medical revolution (LDCs)

• What role does diffusion play here?

Stage 3: Moderate Growth

• Fertility (TFR) drops, therefore CBR drops= a decrease in growth

• CDR drop as well but not as bad as CBR.• What cultural and economic factors play

a role in the declining birth rate?

Stage 4: Low Growth

• CDR and CBR become the same until NIR = 0 (ZPG)

• Population has swelled in stages 2 and 3.

• How does this stage compare to stage 4?

Stage 5? Decline?

• Could see some countries moving into a new stage 5: decline

• CDR would increase to be greater than CBR

• Russia, Germany, Italy, Japan

Why is it important to know?

• Countries with high population of younger people have different problems than countries with high old population– Aging population in MDCs vs. low life

expectancies in LDCs– Differing dependency ratios

• US- high elderly dependency (over 65) • Africa- high young dependency (under

15)

Quick Write• Explain the 2 differences in the way

countries transition now (Mexico/LDCs) from in the past (Sweden/MDCs).

• See next slide for answer

0

10

20

30

40

50

60

1775 1800 1825 1850 1875 1900 1925 1950 1975 2000

SwedenBirth Rate

Death Rate

MexicoBirth Rate

Death Rate

Births/Deaths per 1,000

1950

Review DTM

• Stage 1• Stage 2• Stage 3• Stage 4 • Stage 5

Population Pyramids

Bar graphs that show us:• Sex ratio- # of men per 100 women• Age distributions• Dependency ratio- under 15, over 65.• CBRs, CDRs, IMRs• Visual representations of the stages of

the Demographic Transition

Population Pyramids

Post War Baby Boom and Declining Birth Rate. Stage?

World Population Pyramid. What stage is the world in?

Countries in the Dem. Tran.–Three examples:

Cape Verde = High growth (Stage 2)

Chile = Moderate growth (Stage 3) Denmark = Low growth (Stage 4)

Cape Verde

Wide base, skinny top

Chile

Slimmer base, widening top

Denmark

Slimmed base, widest top

Extremely High Birth and Death Rates. Stage?

Moderate to low Population Growth. Stage?

Skinnier middle-top makes it stage 3. When lower bulge gets older (lives longer/doesn’t die) then it will be in transition to 4. Compare to Japan on next slide.

Post War Baby Boom and Declining Birth Rate. Stage?

Skinnier bottom with wider top makes this a stage 4. The skinnier the bottom gets, the more it is in transition to stage 5, i.e. the more “top heavy” it gets.

Analysis

What can we determine about these countries':• CBRs/IMRs/TFRs?• CDRs?• Life expectancy?• Development levels (MDC/LDC)?• Dependency ratio?• How are all these concepts related?

Very low stage 2, almost reverting to 1

Stage 2

Stage 2 moving toward stage 3

Stage 3 in Transition

Stage 3?- stable/low growth

Stage 5? Aging population, very low CBR

Population Growth and the Dem. Tran.• Population spike of second half of the 20th

century means few countries are in Stages with low population growth right now.

• Most countries are in stages 2 and 3 and only a few will reach stage 4 in near future = increased world population growth

• Problem: In LDCs, CDRs have declined with diffusion of medical technology but CBRs remain high due to cultural and economic reasons. We talked about the past vs. present transitions that countries make (see Quick the Write).