Population Composition: Age-Sex Structure, Pyramid Shapes and Occupational Structure

Age, Sex and Pyramid Shapes

Age-Sex Composition and Sex Ratio

• Knowing how a population splits by age and sex tells planners what services it actually needs. A population heavy with young children needs schools; one heavy with elderly people needs healthcare and pensions instead.
• Sex ratio is usually written as the number of females per 1,000 males. A ratio below 1,000 means males outnumber females, and can point to factors like sex-selective practices or male-biased migration.
• The working-age share, roughly ages 15 to 64, is the raw material for what economists call a demographic dividend: faster growth when that share is large relative to dependants.

Reading the Three Pyramid Shapes

• A population pyramid stacks age groups as horizontal bars, males on one side and females on the other. Its overall shape shows a population’s history and future at a glance.
• An expansive pyramid has a wide base tapering sharply to a narrow top. High birth rates are still adding many more young people than old people are dying off, typical of developing countries.
• A constrictive pyramid has a base narrower than its middle. Birth rates have fallen below what they once were, so there are fewer children now than adults born decades ago, typical of developed countries.
• A stationary pyramid is roughly even and slowly tapering. Birth and death rates have both settled low and stayed balanced, so each age group is close in size to the ones around it.
• Kenya shows a textbook expansive shape, broad base and rapid narrowing, since high infant mortality alongside high births leaves relatively few people reaching old age. India’s pyramid still has a wide base but narrows less sharply, since falling death rates let more infants survive into adulthood. Japan’s pyramid narrows at the base itself, reflecting low birth rates and long lifespans.

Rural-Urban Mix and Work

Rural-Urban Composition and Literacy

• What share of a population lives in villages versus cities is itself a development indicator, built on the same distribution and density ideas covered in our World Population article. Industrialising economies see this share shift toward cities over time, as farm labour moves to factory and service jobs.
• Literacy rate measures the share of the population, usually aged 7 or above, that can read and write with understanding. It correlates closely with a country’s overall human development level.
• Male and female literacy rates rarely match. A wide gap between them usually points to unequal access to schooling, not a difference in ability. A full-state breakdown appears in this site’s own Census 2011 population data article.

Occupational Structure as a Development Clue

• Occupational structure is the share of a workforce employed in each broad activity type: primary (farming, mining), secondary (manufacturing), and tertiary and quaternary (services, knowledge work), a classification covered in detail in our worker classification article.
• As economies develop, workers typically move from primary activities toward secondary, then toward tertiary and quaternary activities. Occupational structure is therefore a rough proxy for a country’s stage of economic development.
• A country with an expansive pyramid and a workforce still dominated by primary activities is often still early in its development path. The two indicators tend to move together for this reason.
• India illustrates this pattern well. About 64% of its workforce works in primary activities, against 13% in secondary and 20% in tertiary activities.