demographic transition model (dtm). key vocabulary crude birth rate (cbr) crude death rate (cdr)...

Defined• CBR: total number of live births in a year for every 1,000 people alive in the

society• CDR: the total number of deaths in a year for every 1,000 people alive in

the society• NIR: the percentage growth of a population in a year, computed as the

crude birth rate minus the crude death rate• TFR: the average number of children a woman will have throughout her

childbearing years• IMR: the total number of deaths in a year among infants under 1 year old

for every 1,000 live births in a society• Life Expectancy: the average number of years an individual can be expected

to live, given current social, economic & medical conditions. Life expectancy at birth is the average number of years a newborn infant can expect to live.

• Doubling Time: The number of years needed to double a population, assuming a constant rate of natural increase

Demographic transition model

The demographic transition model shows how a population will change over time as it changes from an agrarian society to an industrial, and post-industrial one.

Population



Population

Stage 1.Birth and death rates are both high, leading to a low but stable population.

High fluctuatingUK pre 1760/Industrial Revolution.Remote tribal groups presently.



Population

Stage 2.Birth remain high but now death rates start to fall dramatically, leading to a rising population.

Early expandingUK pre 1760-1880.Peru/Sri Lanka/Kenya presently.



Population

Stage 3.Birth start to fall now and death rates continue to fall, causing the population to continue to rise but less quickly now as the gap between births and deaths is closing.

Late expandingUK 1880-1940China/Cuba/Australia presently.



Population

Stage 4.Birth and death rates are now both low, causing the population to be more stable but high.

Low fluctuatingUK post 1940Canada/USA/Japan.

Stage 1 – High Fluctuating

High CBR• Reasons:

– High IMR– Lack of family planning– Need for workers– Children are economic

assets(support parents)– Religious beliefs

• Roman Catholics• Muslims• Hindus

High CDR• Reasons:

– Disease– Famine– War– Poor hygiene & sanitation– Lack of healthcare– Lack of education

Demographic transition modelPopulation

Stage 1.Natural increase (population growth) is low because although there are a lot of births the similarly high number of deaths effectively cancels them out, leaving a low but stable population.

Stage 2 – Early Expanding

High CBR• Same reasons as Stage 1

Declining CDR• Reasons:

– Improved healthcare– Improved sanitation– Improved food production– Decreasing IMR– Outside stimulus


Stage 2.Natural increase (population growth) is high because there is now a large gap between births and deaths, increasing the population rapidly.

Stage 3 – Late Expanding

Declining CBR• Reasons:

– Changing status of women• Cairo Conference

– Availability of family planning– Lower IMR– Increased standard of living– Better technology = lower

demand for workers– Welfare/Retirement

Declining CDR• Same reasons as Stage 2


Stage 3.Natural increase (population growth) remains high due to the gap between births and deaths but as this stage the increase slows as births and deaths match up again.

Stage 4…and 5?

Stage 4 – Low Fluctuating• CBR & CDR are low• Population is stable

Stage 5• CBR drops below CDR• Population starts to

decrease• Officially only 4 stages• Not part of the original

DTM, but some geographers have added it

• So if there is 5, why not 6?


Stage 4.Natural increase (population growth) is again low as births and deaths virtually cancel each other out, but now the population is high..

Population Concentrations

1. East Asia2. South Asia3. Europe4. Southeast

Asia5. Northeast

North America

6. West Africa

East Asia

• Eastern China, Japan, Korean peninsula & Taiwan

• ¼ World’s Population• 5/6 live in PRC• China: ½ of population

work as farmers (rural)• Japan & Korea– 40% live in 3 major cities

(Tokyo, Osaka, & Seoul)

South Asia

• India, Pakistan, Bangladesh & Sri Lanka

• ¼ World Population• ¾ live in India• Most are farmers in rural

areas

Europe

• 3rd Largest (including European portion of Russia)

• 1/9 of world population

• ¾ live in cities– > 10% farmers

Southeast Asia

• Indonesia, Papua New Guinea & Philippines

• Largest = Java = 100 million

• Most work as farmers in rural areas

Emerging Population Concentrations

Eastern North America• NE U.S. & SE Canada• 2% of the world’s

population• Most urbanized

concentration– >2% farmers

West Africa

• West Africa, including south facing coast & Nigeria

• 2% of the world’s population

• Nigeria = most populous African nation, ½ of this concentration

• Most work in agriculture

Population Density

1. Arithmetic Density2. Physiological Density3. Agricultural Density

Arithmetic Density

• “The total number of people divided by the total land area”

• Pros– Easy to compare

• Cons– Tells us “where,” but not “why”

Physiological Density

• “The number of people per unit of area of arable land, which is suitable for agriculture”

• Pros– More meaningful

• Cons– Higher = more pressure to produce more food

Agricultural Density

• “The ratio of the number of farmers to the total amount of land suitable for agriculture”

• MDCs– Lower agricultural density– Fewer farmers, more extensive areas– Due to better technology & finances

Overpopulation

• Carrying Capacity is the ability of a resource base to sustain a population

• Overpopulation– Too many people compared with the resources of

region/country

Thomas Malthus

• Thomas Malthus– English economist– Determined the

world’s rate of population increase was higher than the development of food supply

• Theory– Population grows

geometrically– Food grows

arithmetically

Neo-Malthusians

• Argue that recent growth is worse than Malthus projected1. Malthus’ theory is almost 200 years old2. Many LDCs are progressing due to help from MDCs

rather than progressing on their own1. Bigger gap between population & resources

3. World population is outpacing other resources other than just food

1. Environmental destruction2. Lack of land3. Non-renewable energy

Critics

• Possibilism• Technology• Growth = more

production• Growth = more new

inventions

Population Pyramids: How they work…

• Males on the left, females on the right• Youngest on the bottom (0-4), oldest on the

top (100+)• Generally done as a percentage of the

population, sometimes as total numbers

• Shape of the pyramid is generally shaped by the CBR in a country

Population Pyramids & DTM

• Population Pyramids and the DTM can generally by applied together

• Certain shapes have been associated with specific stages of the DTM

Pyramid for Stage 1

• Wide base = very high birth rate• Narrows very quickly = high death rate• Very few reach old age

Pyramid for Stage 2

• Wide base = High birth rate• Wider & taller = people living longer

Pyramid for Stage 3

• “Domed” shape = more people living to be older

• Proportionately fewer births

Pyramid for Stage 4

• Small base, small top• Bulge in the middle

All four Stages

Concave Profile

Convex Profile

8 Great Modern Migrations

Ravenstein’s Laws of Migration• British sociologist (1834 – 1913)• Laws of Migrations:

1. Most migrants go only a short distance1. Distance Decay

2. Most migrations proceed step-by-step (Lee’s Model)3. If they do move a long distance, they are more likely to travel to a

big city (Gravity Model)4. Every migration flow produces a counterflow

1. Rural migrants move to city; city dwellers move to suburbs

5. Most migration is from rural to urban6. Families are less likely to make international moves than young

adults7. Most international migrants are young males

1. Changed with time; women comprise 40-60% of International migrants (55% of U.S. migrants)

Types of Migration

Voluntary Migration• Choose to migrate• Remember

– Must be permanent– If they return (guest workers,

time-contract workers) they are not included in these numbers

Forced Migration• a.k.a. Involuntary migration• Examples:

– Triangle Trade• Atlantic Arm

– Native American relocation in Great Plains region of U.S.

Global Migration Trends

• From less-developed Stage 2 countries

• To more-developed Stage 4 countries

• 3 largest migration flows– Asia to Europe– Asia to North America– Latin America to North America

• Net In Migration: Europe, North America & Oceania

• Net Out Migration: Asia, Latin America & Africa

U.S. Immigration Trends

• 3 Phases1. American colonies

– European settlement, mainly British– African slaves

2. Nineteenth-Twentieth Century1. 1840-1850: Western Europe 2. 1880s: Northern Europe 3. Beginning of Twentieth Century: Southern & Eastern Europe

3. 2nd Half of Twentieth Century1. Latin America & Asia

• Periods of Decline– U.S. Civil War, 1893 Depression, WWI, Great Depression, WWII

Key Terms Defined

• Push Factor: Factor that induces people to leave old residences.

• Pull Factor: Factor that induces people to move to a new location.

• Intervening Obstacle: An environmental or cultural feature of the landscape that hinders migration.

• Intervening Opportunity: A favorable environmental, economic or cultural feature that redirects migration.

Lee’s Model of Migration

Push Factors1. 2. 3. 4. 5. 6. 7. 8.

Source Region

InterveningObstacle

Migration

Pull Factors1.2.3. 4.5.6. 7. 8.

Destination

Push/Pull Factors

1. Economic2. Environmental3. Cultural

• Economic & Environmental push/pull factors are generally associated with voluntary migration.

• Cultural push/pull factors are generally associated with forced migration

• Note: people tend to move on excessively positive images/expectations that may not always be accurate

Push/Pull Factors

Push Factors• Economic

– Poverty– Few job opportunities– Low wages

• Environmental– Hazardous regions– Adverse physical conditions– Too little water/too much water

• Cultural– Slavery– Political instablity– Religious/ethnic persecution

(refugees)

Pull Factors• Economic

– Higher standard of living– More job opportunities– Higher wages

• Environmental– Stable climates

• Cultural– Stable political conditions

Intervening Obstacle/Opportunity

• Examples of Obstacles– Environmental

• Mountains, rivers, bodies of water, etc.

– Cultural• Passport to leave/visa to come in

– Economic• Run out of money

• Examples of Opportunities– Economic

• New jobs along migration route

– Environmental• Jobs created to divert rivers for irrigation (economic as well)

– Cultural• Move into an ethnic enclave along route

Practical Application of Lee’s ModelSource Region Destination Region

Push Factors

- -- - -

Pull Factors

+ + +

+ +

Migration

Intervening Obstacle

Pull Factors+ +

+

+ +

Push Factors

- -- - - -

Return

Other Destination

Intervening Opportunity

Few ArriveMany

leave

Background

• Interaction is proportional to the multiplication of the two populations divided by the distance between them (distance decay); based on Newton’s Law of Gravity