Most of Humanitys history on Earth has occurred during stage 1.
Humans survived by hunting and gathering. A high and variable CBR.
(fluctuating mid 30s to mid 40s) Despite advent of the Agricultural
revolution c. 8000 BCE, human populations stayed in stage 1 because
crops yields were unstable. A high and variable CDR. (fluctuating
mid 30s to mid 40s) Death and birth rates were high and fluctuating
because of the the uncertain food supplies and lack of medical
technology. Therefore, a low and variable NIR. (fluctuating near
zero) And a stable and relatively low population. STAGE 1: LOW
GROWTH
Slide 3
The world stayed in stage one for about 10,000 years after the
agricultural revolution. Population gains were modest. In 1750,
several nations in Europe and North America entered the second
stage of the Demographic Transition. CBR remains high and stable.
(often in the 40s) CDR declines steeply. (often into the teens) The
countries entered stage two because of the INDUSTRIAL REVOLUTION.
The new manufacturing industry produced massive wealth. In stage 2
countries, the wealth shifted the work patterns and created better
health, sanitation and hygiene, thus lower death rates. Therefore,
the NIR increases steeply. Often as high as 3% African, Asian and
Latin American countries did not begin to enter stage 2 until about
1950. They did not enter stage 2 because of the industrial
revolution but because of the MEDICAL REVOLUTION, which reduced
their death rates. And the population begins to skyrocket. Some
world countries are still in stage 2. Most of Sub-Saharan African
countries are still in stage 2. STAGE 2: HIGH GROWTH
Slide 4
CDR fell in North American and European countries because of
industrialization: A. Farms got machines, excess farmers moved to
cities to work in factories B. Wealth began to spread better living
conditions, better nutrition from farms, better sanitation systems,
better hygiene and medicine LESS DEATH CDR fell in African, Latin
American and Asian countries FOR A DIFFERENT REASON. The MEDICAL
REVOLUTION from wealthy countries (not industries) diffused: A.
better hygiene and medicine LESS DEATH The GAP between high CBR and
low CDR means MORE PEOPLE CDR fell in North American and European
countries because of industrialization: A. Farms got machines,
excess farmers moved to cities to work in factories B. Wealth began
to spread better living conditions, better nutrition from farms,
better sanitation systems, better hygiene and medicine LESS DEATH
CDR fell in African, Latin American and Asian countries FOR A
DIFFERENT REASON. The MEDICAL REVOLUTION from wealthy countries
(not industries) diffused: A. better hygiene and medicine LESS
DEATH The GAP between high CBR and low CDR means MORE PEOPLE THE
EMPHASIS
Slide 5
Stage 3 begins with sharp drop in CBR (often into teens) CDR
continues to fall, but less steeply (often 0-10 range) Because of
sharp drop in CBR, NIR begins to fall sharply. Often around 2%
Therefore, Population still gains, but more slowly European and
North American countries entered stage 3 in early 1900s. Many Asian
and Latin American countries entered recently. Most African
countries remain in stage 2. STAGE 3: DECREASING GROWTH
Slide 6
In Stage 2, CDR dropped because of change in TECHNOLOGY:
Industrial technology in MDCs Medical technology in LDCs In Stage
3, CBR drops for a different reason, a change in SOCIETY: People
choose to have fewer children Since more babies live from stage 2s
CDR drop, couples have fewer children Since fewer people work on
farms and more in factories, fewer children is better Since urban
homes are smaller, fewer children can fit. Many people are trading
rural life for a smaller-scale urban life. This isnt what I meant
when I asked for a room with a view. I should have used birth
control. THE EMPHASIS
Slide 7
In stage 4, the CBR and the CDR approach each other and then
meet.Therefore, NIR approaches 0%And population stops growing.
STAGE 4: LOW GROWTH This is called ZERO POPULATION GROWTH (ZPG):
Both CBR and CDR are low and stable (often around the 10s)
Countries meet REPLACEMENT FERTILITY RATE where births replace but
do not exceed the number of deaths (TFR: 2.1)
Slide 8
Okay, hotshots Quiz time. Which countries are in stage 4 of the
Demographic Transition? Dont Be Fooled: Not all countries with a
TFR of 2.1 or below are stage 4 countries. Some have high CDRs
Others have strict anti-natal policies Dont Be Fooled: Not all
countries with a TFR of 2.1 or below are stage 4 countries. Some
have high CDRs Others have strict anti-natal policies
Slide 9
Countries enter stage 3 because of a change in SOCIETY.
Countries also enter stage 4 because of a change in society: More
women are educated and educated longer (delayed childbirth) More
women pursue careers (delayed childbirth) Daycare is expensive
(fewer children) Better access to birth control (fewer and delayed
children) Increased wealth and leisure = recreation (delayed
children) Think of all those poor schmucks with kids! heh, heh,
heh, Morons. THE EMPHASIS
Slide 10
Possible Stage 5 Death Rates exceed Birth Rates Population
begins irreversible decline THE BIG PICTURE The Demographic
Transition is a model that predicts changes in a countrys CBR, CDR,
NIR and Population as that country goes through changes like the
industrial or medical revolution. All countries are in one of the
four stages. THERE IS ALSO
Slide 11
Stages of the Demographic Transition affect a countrys
population in a few of ways: 1.The overall number of people
(POPULATION grows) 2.The structure of the population The Age
Distribution The Sex Distribution THE EFFECTS
Slide 12
POPULATION PYRAMIDS
Slide 13
A way to depict a countrys population profile graphically
Y-Axis indicates age X-Axis is divided into mirror image Males to
left of splitFemales to right of split X-Axis indicates % of
population Graphed data are AGE COHORTS population divided into 5
year groups POPULATION PYRAMIDS
Slide 14
People aged 65 and older And those aged 14 and younger
DEPENDENCY RATIO is the percentage of a population too old or too
young to work. SEX RATIO is the number of males for every 100
females in a population. In general, slightly more males than
females are born. But females live longer POPULATION PYRAMIDS are
considered DEPENDENTS.
Slide 15
Stage 2 CountriesCape Verde Islands Stage 2 countries have a
wider bottom 1/3 and a narrow top 1/3. POPULATION PYRAMIDS The
birth rate has remained high, so the base is broad. Stage 2
countries have very high dependency ratios often near 50% Stage 2
countries often have 1/3 of population under age 14.
Slide 16
Stage 3 CountriesChile POPULATION PYRAMIDS Stage 3 countries
begin to look more like a classic Christmas tree. As the birth rate
begins to decline, the middle third of the pyramid begins to
fatten. As people begin to live longer, the top third fattens,
too.
Slide 17
Only 1/6 of the population in Stage 4 countries is 14 and under
(it was 1/3 in stage 2) Stage 4 CountriesDenmark POPULATION
PYRAMIDS Stage 4 Countries look more rectangular with the taper
beginning in the upper 1/3 of the pyramid. People are living longer
(top fattens) and having fewer children (bottom slims) Only 1/3 of
the population in Stage 4 countries are dependents (it was in stage
2)