The breakdown of a population into different age groups is a fundamental concept in population geography. This demographic characteristic is typically displayed graphically as a population pyramid, which visually represents the number or percentage of males and females in each age cohort. For instance, a population pyramid with a wide base and narrow top indicates a high birth rate and a relatively short life expectancy, common in less developed nations. Conversely, a pyramid with a narrow base and a wider top signifies a low birth rate and a longer life expectancy, typical of more developed nations. Data used to construct these representations are collected through census data and vital registration systems.
Understanding this population structure is critical for policymakers and researchers for several reasons. It informs decisions regarding resource allocation, such as healthcare, education, and social security. A country with a large youth population requires significant investment in schools and job creation. A country with an aging population necessitates more resources directed towards healthcare and elder care services. Historically, shifts in these demographic structures have influenced social and economic policies, impacting labor force participation, economic growth, and dependency ratios.