Not origional content. Exploration of population pyramids.

1. Population Pyramids = graphic
device that represents a
population’s age and sex
composition.
Pyramid describes diagram’s
shape for many countries in
1800’s when was created.

2. A broad base of younger age groups and
progressively narrowing to apex as older
Populations were thinned by death.
Now there are many different shapes.

4. Quickly growing population of Kenya – jas
,most people in lowest age cohorts
Percentage in older age groups declines
successively with markedly sloping sides.
Typically female life expectancy is
decreased in older cohorts of less
developed countries – 50 for Kenya –
proportion of females in older age groups
is less than in Sweden or U.S.

7. In wealthy countries with very slow rate of
population growth – population is nearly
equally divided - so pyramids have
Almost vertical sides.
War can be reflected by showing depleted age
cohorts and male – female disparities.
The % of a country’s population in each age
group strongly influences demand for goods and
services within that national economy.
Country with high % of young has high demand
for educational facilities and health delivery
services.

8. Dependency Ratio = measure of # of
dependents – old and young that each
100 people in productive years (15 – 64)
Must support.
Population Pyramids show this.
Population pyramids also foretell future
problems from present population policies
or practices. Ex. China’s population
policies skewed in favor of males.

11. Natural Increase = Rate of Natural
Increase of population – derived by
subtracting
The Crude Death Rate from the Crude
Birth Rate.
Natural means increases or decreases
due to migration are not included.
This rate is usually expressed as a % or
rate per 100 rather than 1,000.
Doubling Time = Time it takes for
population to double.

12. Ex. – 2% rate of increase – recorded
1999 by developing world except China
Population would double in 35 years –
since 1% rate would take 70 years to
double.
Population Doubling Time – estimated by
dividing the Growth Rate into the number
70 = ( 70 divided 2 = 35 years).
Globally – Rates of Increase have risen
over history. Thus – doubling time has
decreased.

13. Should world fertility rates decrease - - as
have recently – population doubling time
Will correspondingly increase as it has
since 1990.
Even small annual additions accumulate
to large total increments because of
geometric or exponential (1,2, 4, 8)
instead of arithmetic growth.
Inevitable consequences of doubling or J-Curve
Growth.

15. The Demographic Transition – some
form of braking mechanism must operate
to control totally unregulated population
Growth – voluntary or involuntary.
Demographic Transition – voluntary
relation between population growth and
economic development. – traces changing
levels of human fertility and mortality
associated with industrialization and
urbanization.

16. This model assumes over time – high
birth and death rates will slowly be
replaced by low rates.
The 1st Stage = of process – and demographic
transition model – characterized by high birth
and high but fluctuating death rates. When
births only slightly exceed deaths – the
population will grow only slowly.
From 1 AD to 1650 – for population to increase
from 250 million to 500 million = Doubling Time
of over millenium and a half. Offset by
sometimes catastrophic decline – like bubonic
plague. This 1st Stage no longer found in any
country.

17. This model was developed to explain
population history of Western Europe.
Western Europe entered 2nd Stage with
industrialization 1750 – it’s effects – declining
death rates with high birth rates have dispersed
worldwide without universal industrial
economies.
Rapidly increasing population during 2nd Stage
results from dramatic increases in life
expectancy. This reflects falling death rates due
to advances in medical and sanitation practices,
rising per capita incomes, urbanization that
provides environment where medicine and food
distribution improvements are concentrated.

18. Birth rates don’t fall as soon as death
rates – cultural patterns change more
slowly than technologies.
Many Latin American and South and
Southwest Asian countries show
charcteristics of 2nd Stage.
Annual rates of increase of these
countries are near or above 30 per l,000
and their population will double in 20 to 25
years. Means underdeveloped societies
have been beneficiaries of life
preservation techniques.

19. Third Stage = when birth rates decline as
people begin to control family size.
Urban, industrialized societies may view kids as
economic liabilities, instead of assets as
agrarian societies do.
When birth rate falls and death rate remains low
– population size begins to level off.
4th Stage – End of model – final stage –
characterized by very low birth and death rates.
This results in very slight % increases in
population and doubling times stretching to l,000
years or more.

20. Extension of 4th Stage into 5th Stage –
population decrease has so far been
confined to rich, industrialized countries
Throughout the world – Europe and
Japan.
By 2010 – most world’s population growth
will result from Demographic Momentum
– not 2nd Stage expansion.
Original model made to describe
Northwest European countries as went
from rural-agrarian to urban –industrial.

21. Beginning 1860 – lst death rates then
birth rates began gradual decline.
= Mortality Revolution – first came as
epidemiological transition echoed
demographic transition to which it’s
associated.Many formerly fatal epidemic
diseases became Endemic = continual
within a population. As people developed
partial immunities –mortalities with them
declined.

22. Health of European population increased
with improving animal husbandry, crop
rotation, etc…
Sewage systems, sanitary water supplies
– common in larger cities – hygiene
improved everywhere.
Deaths associated with chronic illnesses
associated with maturing and aging
population increased.
Passed to Age of Degenerative and
Human-Origin Diseases.

23. Increases recently in drug and antibiotic
resistant diseases, pesticide resistance
Of disease-carrying insects, and AIDS
cast doubt on finality of “ultimate” stage.
In Europe – decrease in death rates was
echoed by decreases in birth rates as
societies altered traditional concepts of
ideal family size.