Theories of Population Growth: The Demographic Transition

Theories of Population Growth: The Demographic Transition

Our good friend Hans Rosling • The two world idea Us = Small Families, Long Lives vs. Them = Large Families, Short Lives • We know (from Rosling) that countries aren’t stuck in current population trends • But how do these trends change? • How do you go from “them” to “us”

The Demographic Transition • A population model that describes a country’s change… • from high birth rates and death rates (“them” population pattern) • to low birth rates and death rates (“us” population pattern) • This model focuses only on births and deaths as factors in population growth

Stage 1: Pre-Transition • Birth rates and death rates are both high • Population growth is stable (not going up or down very much) • Natural Increase ≈ 0 • Total Fertility Rate is high • Lots of babies are being born because lots of babies die (high infant mortality rate) Social context: • Subsistence level society (focus is surviving each day) • Poor health care, disease is common, food supply is unreliable

Stage 1 Population Pyramid (use www.populationpyramid.net) Country in this stage: Year: Year Canada was in this stage:

Stage 2: Early Transition • A dramatic drop in death rates occurs • Introduction of healthcare, stable food supply, clean water and sanitation etc. • birth rates remain high • Children needed for “work” on farm, care for aging parents; agricultural society • Population explodes, high natural increase • More people surviving in each age group (population pyramid gets wider for each cohort)

Stage 3: Late Transition • Death rates remain low • Birth rates are high, but start to decrease • Population growth begins to slow as birth rate declines to match death rate • Increased life expectancy, fewer children Social Context: • Shift from agricultural to industrial society • Having lots of children is becoming less beneficial, more of a burden (cost to clothe, shelter, feed, educate etc.) • More women working, families becoming wealthier

Stage 4: Post-Transition • Birth rate has declined to match death rate • Natural increase ≈ 0 so population stabilizes • Immigration/emigration account for any population change • Total fertility at (or below) replacement value Social context • Highly developed, urban society with very small families • Both parents working, starting families later in life cycle (if at all) • Long life expectancy  high dependency load (lots of elderly, and living longer)

Stage 5? • Birth rate drops below death rate • Total fertility is below replacement • Population is declining (a natural decrease) • This is happening in many highly developed countries

Theories of Population Growth: The Demographic Transition