Population and urbanisation
Geography · Key Stage 3 · The School
Reading a pyramid
A POPULATION PYRAMID shows age and sex. A wide base and narrow top means high birth rate and lower life expectancy — a young, growing population. A narrow base and bulging middle means an ageing population, which brings pension and care pressures. Shape tells you the country's situation before you read a single number.
Why people move
PUSH factors drive people away: conflict, drought, unemployment, persecution. PULL factors draw them: work, safety, schools, family. Almost every real migration is a mixture, and describing only one side is how migration gets talked about badly.
Urbanisation
More than half the world now lives in cities. RURAL-URBAN MIGRATION plus natural increase drives it. The results cut both ways: jobs, services and opportunity on one side; informal settlements, pressure on water and sanitation, and congestion on the other. A good answer names both, because the phenomenon is genuinely both.
PYRAMID A: very wide base, narrowing sharply, few over 60. High birth rate, low life expectancy. The pressing need is schools, maternal healthcare and jobs for a young population arriving all at once. PYRAMID B: narrow base, bulging in the middle and top. Low birth rate, long lives. The pressing need is pensions, healthcare and workers. Neither shape is good or bad — each names a different bill coming due.
One number captures why neither pyramid is comfortable. The DEPENDENCY RATIO compares people aged under 15 and over 64 with those aged 15 to 64. A country with 40 dependants per 100 workers has room; one with 80 does not. A wide base pushes it up with children, and a top-heavy pyramid pushes it up with retired people. The shapes are opposite and the pressure is the same: fewer working people supporting more who are not.