Transcript Population Chapter 2

Population
Chapter 2
Importance of Studying Population
6.75 billion people living on Earth—
more than ever
Population grew faster during second
half of 20th century than ever before
Almost all population growth is now
happening in LDCs
Demography
Def.- the scientific study of population
characteristics
Demographers statistically study
spatial distribution of people by age,
gender, occupation, fertility, health,
etc.
Where is the World’s Population
Distributed?
Population cartogram- shows size of the country
relative to its population rather than land area
Population Concentrations
2/3 of people living on Earth are
clustered around 4 regions
East Asia
South Asia
Southeast Asia
Europe
continued
Most of these people in these 4 regions live
near an ocean or river with easy ocean
access
2/3 of world live within 300 miles of an ocean– 4/5
within 500 miles
4 clusters are generally low in elevation,
with fertile soils and a temperate climate
Clusters located in N. hemisphere b/w 10
and 55 degrees latitude except for part of
Southeast Asia
East Asia
1/5 of the world
Includes eastern China, Japan, the Korean
Peninsula, and Taiwan
5/6 live in China
Most along the coast or along Huang and Yangtze
Rivers
26 cities with more than 2 million, 52 with more than 1
million—still 2/3 live in rural areas
Most Japanese live in Tokyo and Osaka
Most Koreans live in Seoul
South Asia
1/5 of World’s population
Includes India, Pakistan, Bangladesh,
and Sri Lanka
¾ live in India
Mostly rural populations- ¼ live in
urban areas
Europe
1/9 of World’s population
Includes European section of Russia
Over 4 dozen countries
Unlike Asia, ¾ of Europeans live in
cities
Largest concentrations near coalfields of
Germany, England, and Belgium
Don’t produce enough food for
themselves– import most of it
Southeast Asia
½ billion people live here
Mostly on islands b/w Indian and Pacific
Oceans
Java, Sumatra, Borneo, Papua New Guinea,
and the Philippines
Mostly farmers in rural areas
Together the 3 Asian concentrations have
more than half the World’s pop., living on
only 10% of the Earth’s land area
Other Population Clusters
Largest cluster in Western
hemisphere is NE US and SE Canada
Chicago to Boston to Newport News
About 2% of World population
Only 3% farmers
Another 2% in West Africa
Most in Nigeria
Like Asia, mostly agriculture
Sparsely Populated Regions
Relatively few people live in areas
where it is hard to grow food
Too dry, too wet, too cold, or too
mountainous
Ecumene- portion of Earth’s surface
occupied by permanent human
settlement
Has grown over time
Dry Lands
20% of Earth’s land surface is
too dry for farming
Still may have valuable natural
resources such as oil reserves
Two largest desert regions are
b/w 15 and 50 degrees N lat. and
20 and 50 degrees S lat.
Wet Lands
Too much moisture can be inhospitable
for humans
Mostly b/w 20 degrees N and 20 degrees
S latitude in South America, Central
Africa, and SE Asia
High rain and high heat lead to rapid
depletion of soil nutrients
If rains are seasonal, it may be possible
to grow enough food to support a large
population
Cold Lands
The poles are either covered in ice or
permanently frozen (permafrost)
Drier than most deserts– small annual
snowfall just never melts
Can’t grow food, therefore very few
humans live in thee areas
High Lands
Highest mountains are steep, snow
covered, and sparsely settled
Exceptions------ people prefer higher
ground if lower areas if temperature and
precipitation are to high
Ex. Mexico City
One of the World’s largest
cities, and its at an elevation
over 7000 ft.
Population Density
Aka arithmetic density- total # of
people divide by total land area
Used to compare countries because the info.
for computing is easy to obtain
About 80 per sq. mile in US (31 per sq.
kilometer)
Bangladesh= 2700 per sq. mile (many
people, small land)
India= 900 (more people than US, less land)
Canada= 8 (big land, few people)
Manhattan island-68,000
continued
Arithmetic density helps answer the
“where” people live question
To explain “why” people live where
they do we need other measures
Physiological Density
Def.- the # of people supported by a unit of
arable land
In US, 445 per sq. mile (172 p/sq. kilo.)
In Egypt, its 6,682 sq. mi
Therefore, 1 unit of arable land in Egypt must feed far
more people than in the US
The higher the physiological density, the
greater pressure that people place on the
land to produce enough food
continued
Comparing physiological and
arithmetic densities helps
geographers understand the capacity
of the land to yield enough food for
the needs of the people
If the physiological density is much
larger than the arithmetic density, much
of the country’s land mass is unsuitable
for agriculture
95% of Egyptian
population lives in the Nile
Valley and Delta
Agricultural Density
Def.- the ratio of the # of farmers to
the amount of arable land
helps account for economic differences
MDCs have lower agricultural densities
because technology and finance allow a
few people to farm extensive land area
Allows pop. to work in other industries
continued
High physiological density paired with
a low agricultural density means an
that a country has an efficient
agricultural system
Natural Increase
Three ways geographers measure pop.
Change
1. Crude birth rate (CBR) – total # of live
births in a year for every 1,000 people
alive in the society
2. Crude death rate (CDR) – total # of
deaths in a year for every 1,000 people
alive in the society
3. Natural increase rate (NIR) – the %
growth of a population in a year,
computed as the crude birth rate minus
the crude death rate
continued
NIR for world is currently about 1.2
All-time high was 2.2 in 1963
About 80 million being added each
year
Highest ever was 1989 when 87
million people were added
With current pop. level, a change of
.01% in the NIR causes a huge swing
in pop. growth
continued
The NIR affects the doubling time» The number of years needed to double the
population, assuming a constant NIR
At current rate, doubling time is 54 years
If remains constant, pop. will reach 24 billion
by 2100
At peak NIR of 2.2 in 1963, pop. was
doubling every 35 years
– At constant 2.2 rate, 2100 pop. Would be 50
billion
continued
Almost 100% of natural increase is
clustered in LDCs
More than 2% in most of Africa, Latin
America, and the Middle East
Actually negative in Europe
2/3 of World pop. growth during past 10
years has been in Asia
Fertility
Total fertility rate (TFR) – the
average number of children a woman
will have throughout her childbearing
years (15-49)
Attempts to predict the future behavior of
individual women in a world of rapid
cultural change
TFR for world is 2.7
Much higher in LDCs than MDCs
Over 6 in some African countries
Mortality
Infant mortality rate (IMR)- the
annual # of deaths of infants under 1
year of age, compared with total live
births
Per 1000 births
Very high in Africa, very low in Europe
A reflection of the country’s health care
system
US has a higher IMR than Canada and
Europe
– Many poor in US can’t afford health care
continued
Life expectancy- the average # of
years a newborn infant can expect to
live at current mortality levels
Higher in MDCs– average late 70s
Lower in LDCs- only 40s in most of
Africa
continued
NIR, CBR, TFR, IMR, and life
expectancy distributions follow similar
patterns
More developed regions have lower NIR,
CBR, TFR, and IMR –with higher
average life expectancy
CDR does not follow this pattern
The combined CDR is lower for LDCs than
MDCs
– This is due to their stages in the process of
demographic transition
Demographic Transition
Def.- the process of change in a
society’s pop. from a condition of high
CBR and CDR and low NIR to a
condition of low CBR and CDR, low
NIR, and a higher total pop.
4 stages have been identified
As a country moves from one stage to
the next, it will never go back
Demographic Transition
Stage 1: Low Growth
Most of human history fits this
category
CBR and CDR vary from year to year,
but always remain high
In effect they cancel out the possibility
of pop. growth
NIR basically zero
continued
Most were hunter/gatherers during
this period
Pop. would increase when there was an
abundance of food, but would decrease
when it was hard to come by
About 8000BC the pop. began to
grow by several thousand each year
From about 5 mill. In 8000BC to 800
million in 1750
continued
Agricultural revolution- when
humans first domesticated plants and
animals and no longer relied entirely
on hunting and gathering
There was now a more stable food
supply, but it could still be unpredictable
Therefore, stage1 continued because of
things like war and famine
No country still in this stage
Stage 2: High Growth
Soon after 1750 the World pop. grew
10 times faster than it had ever done
In 1750 about ½ million people were
added to the pop.– In 1800 5 million
were added
Some countries moved into stage 2
CDR plummets, while CBR remains high
Leads to high NIR
Continued
Industrial revolution- a series of
improvements in ind. technology that
transformed the process of
manufacturing goods
Led to never seen before amount of
wealth, which made some communities
healthier places to live
Machines helped farmers increase
harvests and freed people to work in
factories
continued
Sanitation and personal hygiene were
improved, sewers were installed
People were healthier and lived longer
European and NA countries entered
stage 2 around 1800
Most African, Asian, and Latin American
did not until 1950
In 1900 8 million people were added,
2000 80 million were added
continued
The LDCs moved into stage 2 for
different reasons than the MDCs
Medical revolution- medical
technology from Europe and US
diffused to LDCs eliminating many
causes of death and allowed people
to live longer
Stage 3: Moderate Growth
CBR drops sharply, CDR slowly
declines
CBR still greater than the CDR, but
NIR is not as high
European and NA countries made the
transition in the first half of the 20th
century
Most LA and Asian countries have
recently moved
Most African countries are still in stage 2
continued
The sudden drop of the CBR is
caused by a change in social customs
People choose to have fewer
children, they are more likely to live in
cities and not on a farm—making
children an economic liability instead
of an asset, and urban homes often
don’t have enough space for large
families
Stage 4: Low Growth
CBR declines to the point where it
equals CDR, and the NIR approaches
zero
Called zero population growth
can occur when the CBR is slightly higher
than the CDR because some females die
before reaching childbearing years
A TFR (total fertility rate) of 2.1 produces
zero pop. growth (not counting immigration)
continued
Stage four countries can be identified
by looking at a map of TFR
In the US the TFR has moved slightly
below zero population growth since
2000
continued
Social customs again help explain the
transition
Women work outside the home, birth
control is more accepted and more
available
Some European countries like Russia
have negative NIRs (more deaths
than births) – blame it on the
communists—high pollution and
unhappy people
continued
Demographic transition is almost like
a cycle
Stage 1 little or no natural increase
Stage 4 little or no natural increase
2 major differences
Stage 1 CBR is high 35-40, stage 4 it’s
low 10
Total pop. Is much higher in stage 4
Demographic Transition
Population Pyramids
The stage of demographic transition
gives a country a distinctive
population structure
Demographic transition effects the
structure in 2 ways
1.
2.
% of population in each age group
Distribution of males and females
Continued
Population pyramid- a bar graph
representing the distribution of
population by age and sex
Pop. % is broken down into 5 year
age groups
Men on the left, females on the right
Shape determined primarily by CBR
Stage 2 pyramid like—stage 4
rectangular
Age Distribution
Dependency ratio- the # of people
who are to young or too old to work,
compared to the number of people in
their productive years
The larger the % of dependents, the
greater the burden on the working pop.
continued
The pop. Is divided in to three
groups to compare dependency
ratios
0-14
2. 15-64
3. 65 and older
Group 1 and 3 are generally
considered dependents
1.
continued
Stage 2 countries have about 50%
dependents
Stage 4 only about 33%
Makes the dependency ratio 1:1 in
stage 2 countries and 1:2 in stage 4
Young dependents outnumber elderly
10 to 1 in stage 2—about even in
stage 4 countries
Continued
Stage 2 countries– 1/3 of pop. is
under 15
Makes it hard for poorer countries to
provide enough schools, hospitals, and
daycares
Stage 4 countries have a “graying”
population
US spends more than ¼ of budget on
Social Security and healthcare for older
Americans
Sex Ratio
Def.- the number of males per
hundred females in the population
Varies among countries
In general, slightly more males are born,
but they also have higher death rates
In Europe in US it is 95:100, it is
102:100 in the rest of the world
In US, males under 15 outnumber
girls 105:100 until about age 40
Malthus on Overpopulation
Wrote An Essay on the Principle of
Population in 1798
Claimed that the population was growing much
faster than the food supply
Pop. Growing geometrically, food supply only
arithmetically
Malthus wrote this several decades after
England entered stage 2
Believed pop. Growth would drain all countries
of resources unless “moral restraint” was used
to lower the birth rate or disease, famine and
war raised the death rate
Neo-Malthusians
Argue that 2 char. of recent pop.
growth make the theory even more
scary
1. Most pop. Growth is in poor
countries that don’t have many
resources to begin with
2. World pop. Growth is outstripping
other resources besides food (ex.
Energy)
Malthus’s Critics
Viewed as unrealistically pessimistic
because he assumed the world’s food
resources as stable, not expanding
Humans have the ability to adapt to the
environment and sometimes adapt the
environment (called _______________)
Other critics argue that the World is
better off with 6 billion people than 1
billion because of the economic
development that has occurred
Declining Birth Rates
On a global scale Malthus’s theory
has not come true
Food production has increased faster
than the NIR since 1950
NIR for the world declined in the
1990s from 1.8 to 1.3
Can only happen because of a rise in
the CDR or a decline in the CBR
Cont.
The decrease in the NIR is largely
the result of declining birth rates
Has happened for two reasons
1. Economic development
2. Distribution of contraceptives
Economic Development
Wealthier communities have more
money to spend on education and
healthcare programs that lower birth
rates
If women go to school and learn
employment skills they will have more
economic control over their lives
Distribution of Contraceptives
In LDCs, demand for contraception is
greater than the supply
Which means if more are distributed,
more will be used and birth rate will
decline
About ¼ of African women use
contraceptives
Economic, religious, and educational
reasons for this
World Health Threats
In some countries high CDRs have
resulted in the declining NIR
Epidemiologic transition- distinctive
causes of death in each stage of the
demographic transition
Epidemiologic Transition Stages 1
and 2
Stage one has been called the stage of
pestilence and famine
Infectious and parasitic disease were principal
causes of human death
Ex. Black Plague
Stage 2 has been called the stage of
receding pandemics
– A disease that occurs over a wide geographic area that
affects a very high proportion of the population
Can be reduced by improved sanitation, nutrition, and
medicine
continued
Death rates didn’t decline immediately
in stage 2 after industrialization
The working poor lived in
overcrowded slums – had high death
rates
Ex. Cholera
Epidemiologic Transition Stages 3
and 4
Stage 3 is known as the stage of
degenerative and human-created
diseases
Decrease in deaths from infectious
diseases and an increase in chronic
disorders associated with aging
Stage 4 known as the stage of
delayed degenerative diseases
Medical advances allow people to live
longer even with degenerative diseases
Epidemiologic Transition Possible
Stage 5
Some argue for a stage of
reemergence of infectious and
parasitic diseases
3 reasons for possible reemergence
1. Evolution of microbes
2. Poverty leads to sub-par medical
care
3. Improved travel
continued
Ex. Avian Flu
Only a modest change in its makeup would
make humans very susceptible
Would become a pandemic
AIDS
20 million have died and 40 million are
infected worldwide
Mostly effects LDCs now
25 million in sub-Saharan Africa