Chapter 2: Population

Key Questions/Big Ideas

• Where is the world’s population distributed? • Where has the world’s population increased?• Why is population increasing at different rates

in different countries? • What tools do demographers use to study

population?

Ecumene: the portion of the earth occupied by permanent human settlement.

Geographia, Claudius Ptolemy (83 – 161 AD) Source: wikipedia

Cartograms

Population Cartogram

Where is human population concentrated?

• http://www.worldmapper.org/animations/wm01to02.html

• Two thirds of world population lives in 4 regions: – East Asia– South Asia– Southeast Asia– Europe

Interactive population map

• http://www.worldmapper.org/svg/map2/index.html

Density

• Arithmetic• Physiological• Agricultural

Arithmetic Density• The total number of people divided by the

total land area

Kowloon City, Hong Kong 1989 (Picture Source: Wikipedial

Physiological Density

• The ratio of the number of people supported per unit area of arable land (land suitable for farming)

Agricultural Density

• The ratio of the number of farmers to the total amount of arable land

What do these densities tell us?

• A high density does not necessarily mean that a country has a high population count.

• If a country has a high physiological density then that means that the country has difficulty growing enough food.

What do these densities tell us?

• A higher agricultural density suggests that the available agricultural land is being used by more and may reach its output limit sooner than a nation that has a lower agricultural density.

• A country with a lower AgD may have more advanced farming techniques in place so that not as many people farm a large area of arable land using efficient machinery

Population Increase

• Natural Increase• Fertility• Mortality

Natural Increase

• Crude Birth Rate (CBR) 20 births per 100 people alive=20

• Crude Death Rate (CDR)5 deaths for every 1000 people alive=5

NIR=CBR-CDR(converted to percentages)Ex. 2%-.5% = 1.5% Natural Increase Rate

Doubling time

• How many years does it take to double the world’s population?

• What factors does this figure depend on? – total population to start with– NIR

Whaot

World Population Growth Over Time

1CE

1900CE

Fertility

• Total Fertility Rate (TFR) is the average number of children a woman will have in her childbearing years (15-49)

• How does TFR differ from CBR? – Attempts to predict the future behavior (and, by

extension, population), whereas CBR gives a picture of society at that moment

World Fertility Map (2005-2010)

Total Births

Mortality

• How long do people live? • What increases life expectancy for adults?• Why do babies and children die?• What is IMR? • Why is it higher in some places than others? • Why is it so high in the United States, relative

to other MDCs?

Total Life Expectancy

Increased Life Expectancy

Increasing Life Expectancy

• "... adding person-years-of-life back into the life table is far easier to accomplish when it involves saving infants and children from dying of infectious diseases than ... saving people over the age of 70." S. Jay Olshansky, 2005

Infant Mortality Rate

Total Births Attended

Percentage of Births Attended

• http://www.globalhealthfacts.org/data/topic/map.aspx?ind=77

Connection: Fertility and Mortality

"...how many of us realize that, in much of the world, the act of giving life to a child is still the biggest killer of women of child-bearing age?" Liya Kibede, 2005

Population Pyramids

• What are they?• What can we use them for?

Population Pyramids: Definition

• A display of a country’s population in groups of age and gender.

• Normally shows the percentage of the total population in 5-year age groups, the youngest group being 0-4 years of age at the base of the pyramid and the oldest group near the top.

• Shape of a pyramid is determined primarily by the CBR (Crude Birth Rate) over time in the community.

Some further definitions…

• Sex Ratio: number of males per hundred females in the population is the sex ratio.

• Dependency ratio: number of people who are too young or old to work, compared to those who are in their productive years.

How do we use Population Pyramids?

• The age structure of a population is extremely important in understanding similarities and differences among countries.

• Can help us see what stage of the demographic transition a given country is in

http://en.wikipedia.org/wiki/Population_pyramid

Population Pyramids of LDCs and MDCs

Youth Bulge

The Demographic Transition

• Stage 1: Low Growth• Stage 2: High Growth• Stage 3: Moderate Growth• Stage 4: Low Growth

Stage One: Low GrowthPre-modern

• Balance between birth and death rates (both high)

• Short life expectancy• Population growth slow (.05% TIR)• Doubling time 1-5,000 years (vs. 30-40 of late

20th century!)• Pattern broken in Western Europe in late 18th

century

World Population since the Middle Ages

Stage Two: Rapid GrowthUrbanizing/Industrializing

• Quickly rising population • Decline in death rate– Consistent food source (Agricultural Revolution of

18th century)– Improved health conditions (water supply,

sewage, personal hygiene)• Birth rate remains high

Demographic Change in Sweden

Stage Three: Moderate GrowthMature Industrial

• Birth rate declining• Low death rate; longer life expectancy• Immigration from less developed countries

may account for much of the population growth in MDCs that are in Stage III

• China, South Korea, and Cuba are quickly approaching Stage III

• U.S. is in Stage III

Chile: Stage 3

Stage Four: Low Growth Post-Industrial

• Low death rate• Low birth rate• Higher dependency ratio• Longer life expectancy• Germany, Denmark are examples

The Census

Picture Source: blogs.villagevoice.com

Picture Source: simple.wikipedia.org

Malthus’ Principle of Population

• 1766-1834• Political economist in

England• Concerned by decline of

living conditions caused by three things: – overproduction of the

young (fertility)– Inability of resources to keep

up with rising population– Irresponsibility of lower

classes

Source: UC Berkeley Museum of Paleontology;

Malthus’ theory of overpopulation

• Poverty and famine are natural outcomes of population growth and insufficient food supply

• If left unchecked (i.e. family size regulated), overpopulation will exhaust resources and famine will take over the world

Epidemiology

• Epidemic• Pandemic

Epidemiologic transition

• Stage 1• Stage 2• Stage 3• Stage 4• Stage 5?