Population Geography

Terms to Know

BR(birth rate) # of births/1000 in population

DR(death rate) # of deaths/1000 in population

RNI(rate of natural increase) (BR-DR)÷10

IMR(infant mortality rate) # of infant deaths/1000 live births

TFR(total fertility rate) avg. # of children born to a woman of childbearing age

given her country’s BR and DR Exponential Growth Website

Demographic Transition Model

It  is based on an interpretation begun in 1929 by the American demographer Warren Thompson, of the observed changes, or transitions, in birth and death rates in industrialized societies over the past two hundred years or so.

Demographic Transition Model

It is an idealized, composite picture of population change in these countries. The model is a generalization that applies to these countries as a group and may not accurately describe all individual cases. Whether or not it applies to less developed societies today remains to be seen.

Stage One

Both high birth rates and death rates fluctuate in the first stage of the population model giving a small population little access to birth control many children die in infancy (high infant mortality) so

parents tend to have more children to compensate in the hopes that more will live

children are needed to work on the land to grow food for the family

children are regarded as a sign of virility in some cultures religious beliefs (e.g. Roman Catholics and Hindus)

encourage large families high death rates, especially among children because of

disease, famine, poor diet, poor hygiene, little medical science.

Stage Two

Birth rates remain high, but death rates fall rapidly causing high population growth. improvements in medical care - hospitals,

medicines, etc. improvements in sanitation and water supply quality and quantity of food produced rises transport and communications improve the

movements of food and medical supplies decrease in infant mortality.

Stage Three

Birth rates now fall rapidly while death rates continue to fall. The total population begins to peak and the population increase slows to a constant. increased access to contraception lower infant mortality rate means there is less need to

have a bigger family industrialization and mechanization means fewer

laborers are required the desire for material possessions takes over the

desire for large families as wealth increases equality for women means that they are able to follow a

career path rather than feeling obligated to have a family

Stage Four

Both birth rates and death rates remain low, fluctuating with 'baby booms' and epidemics of illnesses and disease. This results in a steady population. most preventable deaths are avoided

Stage Five???

Total population is declining because birth rates have dropped below death rates.

Not originally part of the model, but many post-industrial countries find themselves in this position.

Population Pyramids

Useful tool for understanding the structure and composition of populations because they graphically portray many aspects of a country, such as sex ratios and age structures

Can give insights into trends in populations over time by their portrayal of the relative number of people in a cohort (example “baby boom”)

DEMOGRAPHIC TRANSITION STAGES

STAGE 1 – Expanding

STAGE 2 – Expanding

DEMOGRAPHIC TRANSITION STAGES

STAGE 3 – Stationary

STAGE 4 - Contracting

Baby Boom in USA

Constrictive Pyramid

Has fewer people in the younger age categories

Has been typical of the US population as baby boom populations shift more to conservative birth rates

Constrictive Pyramid – USA 2004

Expansive Pyramid

Greater numbers of people in the younger age categories

Typical of many developing countries where birth rates are high, but conditions are harsh and life expectancy is short

Expansive Pyramid – Sudan 2004

Stationary Pyramid

Shows roughly equal numbers of people in all age categories, with a tapering towards the older age categories

Countries such as Iceland, show stationary age categories because of relatively low, constant birth rates and high quality of life

Stationary Pyramid – Iceland 2004

Review

If the Earth’s population = 100 people The Demographic Transition Singapore