Demography: The Study Of Human Population May 2026

: High birth and death rates; population size remains stable but low.

: Birth rates begin to fall as society urbanizes and education (especially for women) increases.

: The movement of people across borders. While net migration is zero at a global level, it is a critical driver of "fast demography" at the national level, often offsetting natural population declines in developed countries. The Demographic Transition Model (DTM) Demography: The Study of Human Population

: Both rates are low; the population stabilizes.

The structure and evolution of any population are determined by three fundamental variables: : High birth and death rates; population size

: Death rates fall due to better sanitation and medicine, while birth rates remain high, leading to rapid population growth.

Most modern demographic analysis is framed by the , which describes the historical shift from high birth and death rates to low ones as societies develop. While net migration is zero at a global

: The actual reproductive performance of a population. Demographers measure this through the Total Fertility Rate (TFR) —the average number of children a woman would have in her lifetime. Currently, the world is nearing the "replacement level" of 2.1, below which a population eventually begins to shrink.