Population and demography
Demography is the study of population: how many people there are, where they live, and how those numbers change.
Measuring population
Fertility is the number of births, and the crude birth rate counts births per 1,000 people each year. Mortality is deaths, measured by the crude death rate. Migration is movement in and out of an area. Population change equals births minus deaths plus net migration.
Theories of population
Thomas Malthus warned in 1798 that population would grow faster than food supply, leading to famine and disease. Demographic transition theory describes how societies move from high birth and death rates, through falling death rates and rapid growth, to low birth and death rates. Many wealthy countries now face ageing populations and low fertility.
Reading a population pyramid
A population pyramid shows the population by age and sex. A wide base and narrow top means many young people and rapid growth, typical of countries with high fertility. A more rectangular shape means slow growth and many older people, typical of wealthy countries. Pyramids help plan schools, jobs, and pensions.
Flashcard
The study of population size, composition, and change
Check your understanding
A country's population pyramid has a very wide base and a narrow top. This suggests: