Unit 4: Population Geography

1. World Population Composition

Population Distribution

Population distribution refers to the spatial pattern of where people live. The global distribution of population is highly uneven.

• Ecumene vs. Non-Ecumene: The ecumene is the permanently inhabited portion of the earth's surface, while the non-ecumene refers to uninhabited or very sparsely populated regions (deserts, ice caps, high mountains).
• Factors Influencing Distribution:
  • Physical/Geographical: Availability of fresh water, landforms (plains are preferred over mountains), climate (extreme climates restrict settlement), and fertile soils.
  • Economic: Availability of natural resources, industrialization, and urbanization pull populations.
  • Socio-Cultural & Political: Stable governments, religious significance, and cultural ties influence human settlement patterns.

Population Density

Population density measures the concentration of people in a specific area. It is a vital metric for understanding the pressure on land and resources.

• Arithmetic Density: Total number of people divided by total land area. (General measure, often masks internal variations).
• Physiological Density: Total number of people divided by arable (farmable) land area. (A better indicator of the pressure a population exerts on its food-producing land).
• Agricultural Density: Total number of farmers divided by arable land area. (Indicates the level of agricultural technology and economic development).

Population Growth

Population growth is the change in the number of inhabitants of a territory during a specific period.

• Components of Growth:
  • Crude Birth Rate (CBR): Live births per 1,000 people per year.
  • Crude Death Rate (CDR): Deaths per 1,000 people per year.
  • Rate of Natural Increase (RNI): Difference between CBR and CDR.
• Doubling Time: The time required for a population to double in size at its current rate of growth.
• Spatial Variations: Developing nations generally exhibit higher growth rates due to higher fertility and declining mortality, whereas developed nations exhibit slow, zero, or negative growth.

Age & Sex Structure

The age and sex composition of a population is visually represented by Population Pyramids.

• Sex Ratio: The number of males per 100 (or 1,000) females in a population. Imbalances can result from wars, selective migration, or cultural preferences (e.g., sex-selective abortion).
• Age Structure:
  • Young populations (Expansive Pyramid): Broad base, indicating high birth rates and rapid growth (e.g., Sub-Saharan Africa).
  • Aging populations (Constrictive Pyramid): Narrow base, indicating low birth rates and an aging population (e.g., Japan, Germany).
  • Stationary populations: Rectangular shape, indicating stable birth and death rates.
• Dependency Ratio: The ratio of the dependent-age population (under 15 and over 65) to the working-age population (15-64).

2. Migration

Migration is the permanent or semi-permanent change of residence of an individual or group.

Types of Migration

• Internal Migration: Movement within a country's borders (e.g., rural-to-urban, inter-regional).
• International Migration: Movement across international borders (emigration = leaving; immigration = entering).
• Voluntary vs. Forced: Moving for better economic opportunities (voluntary) vs. fleeing war, persecution, or natural disasters (forced/refugees).

Causes of Migration

Causes are typically categorized into Push and Pull factors:

• Push Factors (Drive people away from origin): Unemployment, poverty, political instability, war, religious/ethnic persecution, natural disasters, lack of services.
• Pull Factors (Attract people to destination): Job opportunities, higher living standards, political freedom, safety, better education and healthcare, kinship ties.

Consequences of Migration

• Economic:
  • Origin: Loss of skilled labor (brain drain), receipt of remittances.
  • Destination: Expansion of labor force, potential strain on public services, economic innovation.
• Demographic:
  • Origin: Population aging (as young people migrate), altered sex ratios.
  • Destination: Population growth, increased birth rates (migrants are often in reproductive years).
• Social/Cultural: Cultural diffusion, increased diversity, potential for ethnic conflicts, changing family structures.
• Environmental: Overcrowding in destination cities, creation of slums, pressure on urban infrastructure.

3. Lee's Model of Migration

Developed by Everett Lee (1966), this model provides a comprehensive framework for understanding the migration process. It posits that migration decisions are influenced by four sets of factors:

1. Factors associated with the area of Origin: Individuals assess the positive (+), negative (-), and neutral (0) elements of their current location.
2. Factors associated with the area of Destination: Individuals perceive the (+), (-), and (0) elements of the potential new location. (Perception often depends on incomplete information).
3. Intervening Obstacles: Barriers that complicate the migration process between the origin and destination. These can be physical (mountains, oceans), political (borders, visa requirements), or economic (cost of travel).
4. Personal Factors: Individual traits (age, gender, education, stage in life cycle, personality) that dictate how the push/pull factors and obstacles are evaluated.

Key Takeaway: Migration only occurs if the perceived positive factors at the destination outweigh the positive factors at the origin, and if the net pull is strong enough to overcome the intervening obstacles.

4. Demographic Transition Theory

The Demographic Transition Model (DTM) describes how populations grow and change as a country undergoes industrialization and economic development. It is traditionally divided into stages:

• Stage 1: High Stationary: High birth rates and high death rates. Population growth is slow and fluctuating. (Pre-industrial societies; no entire country is currently in Stage 1).
• Stage 2: Early Expanding: High birth rates, but rapidly declining death rates (due to improvements in healthcare, sanitation, and food supply). Results in rapid population growth. (e.g., Sub-Saharan Africa).
• Stage 3: Late Expanding: Birth rates begin to fall (due to urbanization, education of women, access to contraception, declining infant mortality), while death rates continue to fall or level off. Population growth slows. (e.g., India, Mexico).
• Stage 4: Low Stationary: Low birth rates and low death rates. Population growth is very slow or zero. (e.g., USA, UK).
• Stage 5: Declining (Proposed): Birth rates drop below death rates, leading to a shrinking and rapidly aging population. (e.g., Japan, Germany, Italy).

5. Population-Resource Regions (Ackerman)

Edward A. Ackerman (1970) proposed a classification of the world into different regions based on the relationship between population size, natural resources, and the level of technological development.

Ackerman identified five distinct population-resource regions:

1. United States Type (Technology-Source Regions):
   • Characteristics: High ratio of resources to population, advanced technology.
   • Features: High standards of living, surplus production, ability to export technology and capital.
   • Examples: USA, Canada, Australia, New Zealand.
2. European Type (Technology-Deficient but Resource-Rich / High Tech-High Pop):
   • Characteristics: High population density relative to resources, but advanced technology offsets the resource deficit.
   • Features: Heavy reliance on importing raw materials and exporting manufactured goods/services. High standard of living maintained through technological efficiency.
   • Examples: Western Europe, Japan.
3. Egyptian Type (Population-Rich but Resource/Tech-Deficient):
   • Characteristics: High population density, limited natural resources, and low levels of technology.
   • Features: Severe poverty, high unemployment, heavy pressure on arable land, low standard of living.
   • Examples: Egypt, Bangladesh, parts of India and China.
4. Brazilian Type (Resource-Rich but Tech-Deficient):
   • Characteristics: Abundant natural resources, low population density, but low levels of technological development.
   • Features: Massive potential for future development if technology and capital are applied. Current living standards may be uneven.
   • Examples: Brazil, parts of Sub-Saharan Africa, Bolivia.
5. Arctic-Desert Type (Resource-Deficient Regions):
   • Characteristics: Extreme physical environments, very low population, limited accessible resources.
   • Features: Little to no agricultural potential, habitation relies heavily on external support or highly specialized local adaptations.
   • Examples: Antarctica, Sahara Desert, Tundra regions.