Age Composition of the Population and its Global Pattern

Concept of Age Composition

Geography Optional Notes {PDF}

Complete Notes Package (Paper I & II) | 3000+ Pages | Instant Download

Discounted Price | Buy Now @ ₹1,180 →

• Age composition (age structure) refers to the distribution of population according to different age groups.
• It is one of the basic demographic characteristics and is crucial for understanding population dynamics.
• The study of age composition helps in analysing:
  • Growth of population
  • Work participation and employment pattern
  • Age at marriage
  • Educational structure of population
• The age structure of a population is primarily determined by three interrelated factors:
  • Fertility
  • Mortality
  • Migration
• As pointed out by Clarke (1972):
  • These three determinants are interdependent, and
  • Change in one leads to corresponding changes in others, thereby influencing overall age structure

⚙️ Determinants of Age Composition

1. Fertility

• Fertility rate determines the proportion of population in different age groups, especially the young population (0–14 years).
• Areas with high fertility:
  • Have a large share of young population
  • Result in high dependency ratio
• Consequences of high fertility:
  • High natural growth of population
  • Increased unemployment
  • Lower age at marriage
  • Inadequate educational attainment
• Impact dimension:
  • These effects are more pronounced on the physical and socio-economic condition of women, especially in less developed countries

🌍 Global Pattern (Based on Fertility & Life Expectancy)

• Countries in Africa, Asia and Latin America:
  • High birth rates
  • Large proportion of population in young age group
  • Often ~40% population below 15 years
• Due to low life expectancy:
  • Proportion of elderly population remains relatively small
• In contrast, developed countries (Europe, North America, etc.):
  • Have low fertility rates
  • Exhibit higher proportion of elderly population
• This reflects:
  • Downward trend in fertility
  • Upward trend in ageing population

2. Mortality

• Age structure is also influenced by mortality rates, especially age-specific mortality
• In developed countries:
  • Low mortality across all age groups
  • Leads to increase in higher age groups (ageing population)
• In less developed countries:
  • Sharp decline in mortality in younger age groups
  • Results in increase in young population

3. Migration

• Migration has a selective impact on age composition, though less predictable than fertility and mortality
• It affects both:
  • Source region
  • Destination region
• Key pattern:
  • Migration usually involves specific age groups (e.g., 25–35 years)
• Effects:
  • Out-migration → decline in working-age population in source region
  • In-migration → increase in working-age population in destination region
• Thus, migration leads to redistribution of age groups across regions

Age-related Data: Age Grouping, Age Indices, Age Pyramid

• Age data of population can be analysed and presented in multiple ways for proper understanding and interpretation.
• The major methods include:
  • Age Grouping
  • Age Indices
  • Age Pyramids

📊 Age Grouping

• Although age is collected as single-year data, it is generally presented in 5-year age groups, such as:
  • 0–4, 5–9, 10–14, 15–19, 20–24, 25–29, 30–34, 35–39, 40–44, 45–49, 50–54, 55–59, 60–64, 65–69, 70–74, 75–79, 80+
• Age is recorded in completed years:
  • Infant below 1 year → recorded as 0
  • Child completing 1 year → recorded as 1
• Interpretation:
  • 0–4 → population below 5 years
  • 80+ → population aged 80 and above
• Significance:
  • Facilitates regional and temporal comparison
  • Simplifies demographic analysis

Broad Age Groups

• For simplification, population is grouped into:
  • 0–14 years (Young / Children)
  • 15–59 years (Adult / Active)
  • 60+ years (Aged / Old)

Demographic Significance of Age Groups

(a) 0–14 Age Group

• Indicates fertility level and stage of demographic transition
• Interpretation:
  • Above 35% → High fertility; Stage II/III (less developed countries)
  • Below 20% → Low fertility; Final stage (developed countries)

(b) 15–59 Age Group

• Considered:
  • Biologically most reproductive
  • Economically most productive
  • Demographically most mobile (Trewartha, 1969)
• Role:
  • Supports other age groups in:
    • Food
    • Clothing
    • Education of children
    • Care of elderly
• Hence, known as economically independent population
• Variation:
  • Does not vary significantly globally
  • Slightly higher in developed countries due to lower fertility
• In developed countries:
  • Often extended to 15–64 years due to higher life expectancy

(c) 60+ Age Group

• Represents aged population / senior citizens
• Characteristics:
  • Economically non-productive
  • Biologically non-reproductive
  • Demographically least mobile
• Hence, economically dependent group
• Pattern:
  • Higher proportion in developed countries due to:
    • Low fertility
    • High life expectancy
• Gender aspect:
  • Higher proportion of females due to higher mortality among aged males

📐 Age Indices

• Age composition can be analysed using quantitative indices
• Importance:
  • Helps in understanding demographic implications
  • Enables regional comparison

(a) Dependency Ratio

• Defined as:
  • Ratio of young (0–14) + aged (60+/65+) population
  • To adult (15–59/64) population
• Expressed in percentage
• Pattern:
  • High in less developed countries due to high fertility

(b) Ageing Index

• Defined as:
  • Ratio of aged population (60+/65+)
  • To young population (0–14)
• Expressed in percentage
• Pattern:
  • High in developed countries due to:
    • Low fertility
    • High life expectancy

🔺 Age Pyramid (Age–Sex Pyramid)

• The graphical representation of age data of population on 5-year age groups in the form of horizontally arranged bars according to proportion of population is known as Age Pyramid.
• It is commonly called Age–Sex Pyramid, because proportion or absolute number of population under different 5-yearly age groups is shown separately for males and females in the same framework.
• The age-groups are arranged on the vertical axis in sequence:
  0–4, 5–9, 10–14, 15–19, 20–24, 25–29, 30–34, 35–39, 40–44, 45–49, 50–54, 55–59, 60–64, 65–69, 70–74, 75–79 and 80+.
• Each age group is represented by a horizontal bar:
  • Left side → Female population
  • Right side → Male population
• Under normal circumstances, the size of population gradually decreases from younger to older age groups, giving it a pyramidal shape.

🔍 Types of Population Pyramids

• Depending on variations in fertility, mortality and life expectancy, three types of pyramids are observed:

1. Expansive Population Pyramid

• Depicts population with a large proportion in younger age groups.
• Characteristics:
  • High fertility rates
  • Low life expectancy
• Example:
  • Less developed countries like India, Bangladesh, Angola, etc.
• Indicates:
  • Youthful population

2. Constrictive Population Pyramid

• Named so because the pyramid is narrow at the base due to lower proportion of young population.
• Characteristics:
  • Declining birth rates
  • Each successive age group becomes smaller
• Example:
  • United States
• Indicates:
  • Ageing population

3. Stationary Population Pyramid

• Shows almost equal proportion across age groups.
• Characteristics:
  • Stable population
  • No significant increase or decrease
• Example:
  • Austria
• Indicates:
  • Stable demographic structure

📏 Median Age

• Defined as:
  • The middle value of age distribution of population
• Characteristics:
  • Varies across countries depending on:
    • Fertility rate
    • Life expectancy
• Pattern:
  • Higher median age → Developed countries (Germany, USA, Japan)
  • Lower median age → Less developed countries (India, Kenya, Bangladesh)
• Significance:
  • Important indicator of age composition and population maturity

Global Pattern

• If analysis of age composition of population is done for broad age groups like 0–14, 15–64 and 65+, globally the proportions are:
  • 0–14 → 26%
  • 15–64 → 64%
  • 65+ → 10%
    • (as per 2021 estimate)
• Among continents:
  • Highest share of children (0–14) → Africa (40%)
  • Lowest share → Europe (16%)
• In Europe, ageing has advanced to such an extent that:
  • Population aged 65+ (19%) exceeds 0–14 age group
• Trend (1975–2021):
  • Global decline in 0–14 age group → from 36.9% to 26.0%
  • Decline is:
    • Slow in Africa → 44.7% → 40.0%
    • Fast in Asia → 39.9% → 24.0%

Key Observations (Country-Level Pattern)

• Age composition varies significantly across continents and countries.
• Asia shows highest variation, while Europe shows lowest variation.
• Example (Asia):
  • Yemen (0–14 → 39.2%) vs Japan (12.5%)
• Japan:
  • Very high 65+ population → results in:
    • High dependency ratio (71.5%)
    • Very high ageing index (233.6%)
• Niger (Africa):
  • Very high young population (0–14) →
    • High dependency ratio (114.1%)
    • Very low ageing index (5.3%)

Conclusion

• Developed countries (low fertility + high life expectancy):
  → High dependency ratio + High ageing index
• Less developed countries (high fertility):
  → High dependency ratio but Low ageing index

Spatial Pattern in India

• Due to considerably high fertility in India, the proportion of population (Census 2011) in:
  • 0–14 age group → 30.8% (high)
  • 65+ age group → 5.5% (low)
• However, there exists marked spatial variation in age composition among states and UTs due to:
  • Variation in fertility behaviour
  • Mortality behaviour
  • Life expectancy
  • Age-selective migration
  • Rural–urban migration

Rural–Urban Variation

• Age composition also varies between rural and urban areas:
  • 0–14 population:
    • Rural → 32.8%
    • Urban → 26.2%
• This results in:
  • Higher dependency ratio in rural areas → 62.3%
  • Compared to urban areas → 45.6%

Age Composition of Population in States/UTs of India, 2011

Key Observations

• Children population (0–14) varies widely:
  • Highest → Bihar (40.1%)
  • Lowest → Goa (21.8%)
• Dependency ratio:
  • Highest → Bihar (81.1%)
  • Lowest → Goa (40.4%)
  • India average → 57.0%

Regional Pattern

• Northern states → Very high:
  • 0–14 population
  • Dependency ratio
• Eastern & North-Eastern states → High to moderate values
• Western states → Low to moderate values
• Southern states → Lowest values

General Trend

• Areas with high proportion of children population:
  • Due to high fertility rate
• These areas also show:
  • Low 65+ population
  • Low adult (15–64) population
• Result:
  • High dependency ratio
  • Low ageing index