Population regime· The columns of time
Industrial growth
1800 → 1950
From about one billion people in 1800 to 2.5 billion in 1950: the species multiplies by two and a half in a century and a half, whereas the first billion had taken three hundred thousand years.
What the evidence shows
The engine is not a rise in births but a fall in deaths, and above all in the deaths of children. What this band draws is less a demographic event than a public health one, in which sanitation, then vaccination, then antibiotics each cut away a body of mortality that had always seemed inevitable. The order matters: mortality falls first and fertility follows only later, and the gap between the two curves is the growth. The band draws the world total and not its composition: between 1800 and 1950 one curve covers regions where that gap had already narrowed and regions where it was only beginning to open.
Bounds and conventions
The 1800 bound is a historiographical convention rather than a measurement, and national censuses become general only in the course of the nineteenth century. Earlier figures rest on tax rolls, parish registers and reconstruction, and carry ranges wide enough that the shape of the curve is more reliable than any single point on it.
Sources
- Klein Goldewijk, K., Beusen, A., Doelman, J., Stehfest, E. (2017). Anthropogenic land use estimates for the Holocene : HYDE 3.2. Earth System Science Data 9, 927–953. Jeu de données versionné, consulté le 2026-08-28.
- United Nations, Department of Economic and Social Affairs, Population Division (2024). World Population Prospects 2024. Révision 2024, consultée le 2026-08-28.