Age Structure – Demographic Transition

Malthusian Theory Thomas Malthus wrote An essay on the principles of population in 1798 Pessimistic Claimed food supply was the main limit to population size Believed that population growth is exponential , but food production is linear Some “neo-malthusians” believe we are starting to see these limits now

Boserup’s Theory Ester Boserup 1965 Population growth will stimulate technology to increase food supply “Necessity is the mother on invention” Population growth naturally leads to development Difficult to “test” due to migration

Why do people have large families? High infant/childhood mortality Have more than you need to be sure some will make it to adulthood Security in old age Children take care of their parents Children are an economic asset Especially in agricultural societies Status of women In many countries women are deprived of rights such as property, career, education Instead they make children Unavailability of Contraceptives In LEDCs many women would like to have them, but cannot get them

Age structure diagram (Also called age-sex histogram or population pyramids) Usually broken into three categories Prereproductive 0-14  Reproductive 15-44  Post reproductive 45-dead  The shape of the age structure diagram is useful in determining future growth

Rapid Growth Slow Growth Male Female Male Female Rapid Growth Guatemala Nigeria Saudi Arabia Slow Growth United States Australia Canada Ages 0-14 Ages 15-44 Ages 45-85+

Zero Growth Negative Growth Male Female Male Female Zero Growth Spain Austria Greece Negative Growth Germany Japan Sweden Ages 0-14 Ages 15-44 Ages 45-85+ Video Link

POPULATION AGE STRUCTURE UNITED STATES What do the yellow bars, moving up the diagram represent? Look at the last structure on the right. What is odd about it? What are the consequences of an aging population?

The Demographic Transition As countries become industrialized their death rates decrease and their population grows Later their birth rates decrease, and the population stabilizes

Model of Demographic Transition Some developing countries may have difficulty making the demographic transition. Demographic trap: Stuck in transition, pop. growth overwhelms economic growth Insufficient capital to move into next stage.

In the transitional stage, which decreases first? Birth or death rates?

Demographic transition Stage 1: High Stationary (pre industrial) Stable population – high birth/death rate Poor living conditions (disease, famine etc.) Low per capita income Poor sanitation High infant mortality Low use of birth control

Demographic transition Stage 2: Early Expanding (Early Transitional) Increased food supply Better sanitation/healthcare Death rate drops, life expectancy increases Infant mortality drops sharply Birth rate still high Population grows rapidly (2.5-3% a year)

Demographic transition Stage 3: Late Expanding (Late Transitional) Industrialization (development) continues Birth rates start to fall thanks to contraception, emancipation of women, education Infant mortality drops sharply Population growth starts to slow and families become smaller

Demographic transition Stage 4: Low Stationary (Industrial) Industrialization is widespread Per capita income is up Birthrate decreases sharply Birth rate approaches death rate Slow to no population growth  Most developed countries are in this phase

Demographic transition Stage 5: Declining (Postindustrial) Populations may not be replaced Fertility rate is low Problems of an aging workforce 85% of the world has yet to reach this stage OMG Best thing ever!

Demographic transition and age structure