Population Geography

Terms to Know BR(birth rate) DR(death 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