Topic 2.5 Demographic and Epidemiological Transition Models

Demographic Transition Model

The demographic transition model illustrates the evolution of a population over time.

Key Metrics

• Crude Birth Rate (CBR): Number of births per 1,000 people.
• Crude Death Rate (CDR): Number of deaths per 1,000 people.
• Rate of Natural Increase (NIR): The difference between the crude birth rate and the crude death rate.

Stage 1: Low Growth

• Characteristics: High crude birth rates and high crude death rates.
• Reasons for High CBR:
  • Cultural preferences.
  • Lack of contraceptives.
  • High infant mortality rates.
  • Agrarian societies need more children for labor.
• Reasons for High CDR:
  • Lack of sanitation.
  • Lack of medicine.
  • Animal attacks.
  • Famine (e.g., locust attacks).
  • War.
• NIR: Very low due to CBR and CDR being nearly equal.

Stage 2: High Growth

• Characteristics: High crude birth rates and falling crude death rates.
• Reasons for High CBR:
  • Sustained cultural preferences.
• Reasons for Falling CDR:
  • Innovations of the Industrial Revolution leading to greater food security.
  • Advances in medicine (e.g., antibiotics).
  • Increased sanitation.
  • Increased life expectancy.
  • Improved nutrition and falling infant mortality rates.
• NIR: Highest rate of natural increase.

Stage 3: Moderate Growth

• Characteristics: Falling crude birth rates and falling crude death rates.
• Reasons for Falling CBR:
  • More women entering the workforce.
  • More women attaining higher education.
  • Improved economics lessening the need for more children.
  • Rising urbanization reducing space for large families.
• Reasons for Falling CDR:
  • Further advances in medicine.
  • Further increasing life expectancy.
  • Even decreasing infant mortality rate.
• NIR: Moderate natural increase rate.

Stage 4: Low Growth

• Characteristics: Very low crude birth rates and low crude death rates.
• Reasons for Low CBR:
  • Women delaying marriage or not marrying.
  • Women seeking to further career and educational aspirations.
  • Increased use of contraceptives and family planning.
• Reasons for Low CDR:
  • Higher incomes leading to greater health outcomes.
  • More disposable income spent on preventative medicine.
• NIR: Natural increase rate near or below zero, leading to zero population growth or a declining population.

Stage 5: Negative Growth

• Characteristics: Extremely low birth rates and rising crude death rates.
• Reasons for Low CBR:
  • Couples choosing not to have kids or delaying having children.
  • Birth rates falling well below death rates.
• Reasons for Rising CDR:
  • Increased urbanization leading to more people together, reintroducing infectious diseases.
• NIR: Negative population growth.

Example: China in Stage 4

• One-Child Policy: A strong social recommendation that led to a skewed sex ratio (114 males for every 100 females).
• Impact: Lowering of the crude birth rate.
• Chinese Women's Revolution: Women are choosing to delay getting married, furthering their educations and careers.
• Wealth and Health: As a manufacturing commercial center, China can devote more of its wealth to maintaining health, lowering its crude death rate.

Practice Example: Bolivia

• Bolivia: Best described as being at stage three of the demographic transition model.

Key Takeaway

The demographic transition model allows geographers to look at changes in a country's crude birth rates coupled with its crude death rates over time.

Epidemiological Transition Model

The epidemiological transition model explains causes of changing death rates and how populations evolve over time based on mortality.

Stage 1: Pestilence and Famine

• Characteristics: Infectious and parasitic diseases are prevalent.
• Diseases: Associated with contact with human and animal waste.
• Issues: Crop failure due to climatic events, locust infestations, and animal attacks.
• Key Terms:
  • Endemic: Diseases that stay in a local area.
  • Epidemic: Diseases that spread through the region and start to infect neighboring regions.
  • Pandemic: Diseases that spread across wide swaths of the geography or from one region to the next.
    • Pan means across.
• CDR: High crude death rates.
• Example: Bubonic plague.

Stage 2: Receding Pandemics

• Characteristics: Improved sanitation, better nutrition coupled with food security by way of improved agricultural practices, and advances in medicine.
• Issues: Pandemics are still a slight issue.
• Outcomes: Increased life expectancy.

Stage 3: Degenerative Diseases

• Characteristics: Fewer infectious disease deaths with increased antibiotic use and increased sanitation.
• Rise in Diseases: Diseases associated with aging, such as cancer, strokes, and heart disease.
• Outcomes: Longer life expectancies and lower death rates.
• Population Growth: Largest population growth.

Stage 4: Delayed Degenerative and Lifestyle Diseases

• Characteristics: Best medical advances in human history are used to extend life expectancy to its highest.
• Factors: Better diets (attributed to better economies and better incomes) and reduced use of tobacco.
• Outcomes: Life expectancy is at its highest.
• Problems: Consumption of junk food and sedentary lifestyles due to higher incomes and commercialization of agriculture.

Stage 5: Reemergence of Infectious Diseases

• Characteristics: Infectious and parasitic diseases make a dramatic return.
• Reasons:
  • Overuse of antibiotics leading to diseases mutating and becoming resistant.
  • Rising urbanization leading to greater contact among populations, leading to a greater potential of infectious spread.
• Outcomes: Slight lowering of the life expectancy.

Example: United States in Stage 4

• Factors: New treatments for debilitating diseases, huge national focus on diet, and cigarette smoking has become taboo.
• Concerns: Intake of sugars and fats.

Key Takeaway

The epidemiological transition model helps to explain change in mortality for a country.