Counting Humanity
Demography is sociology with real data: births, deaths, and moves remaking markets decades in advance.
Core rates (per 1,000 people/year) include the crude birth rate, crude death rate, and natural increase (their difference). Add net migration for total growth:
A population growing at doubles in roughly years, applying the Rule of 70 to human numbers.
Population pyramids photograph age structures: a wide triangle means Stage 2 youth explosions, while a barrel shape means aging Stage 4 societies.
The Demographic Transition
| Stage | Births | Deaths | Population |
|---|---|---|---|
| 1. Pre-industrial | High | High | Barely grows |
| 2. Early transition | High | Falling | Explodes |
| 3. Late transition | Falling | Low | Growth slows |
| 4. Post-transition | Low | Low | Stabilizes |
Urbanization accompanies this shift, concentrating labor and driving Durkheim's move from mechanical solidarity (likeness) to organic solidarity (interdependence).
Pitfall: Fertility drops do not instantly halt growth. Demographic momentum keeps young populations growing for decades because large cohorts have not yet had children.