How the World’s Population Grew
In 1960 Heinz von Foerster and two colleagues fitted a curve to two thousand years of population estimates in the journal Science and found it reached infinity on Friday 13 November 2026. This film explains how populations grow: Malthus's geometric and arithmetic ratios, exponential growth and doubling time, why the billions arrived faster and faster, the demographic transition that bent the curve, population pyramids, the United Nations' projection of a peak in the 2080s, and how Thailand went from six children per woman to about one. Run the doomsday clock, step through the transition, add the billions and reshape the pyramid.
The doomsday curve
A formula that sent humanity to infinity.
A formula with a wall
Divide by a number that shrinks to zero.
Why it seemed to fit
The more people, the faster the growth.
Malthus’s two ratios
People multiply; fields only add.
Doubling time
A rule you can do in your head.
Faster and faster
Until the gaps stopped shrinking.
Where the curves part
The formula kept climbing. People did not.
Deaths fall first
Then a gap opens.
Then births fall
The gap closes again.
The shape of a population
From a pyramid to a column.
A peak this century
And then, slowly, a decline.
A transition at speed
Six children, then two, then one.
Friday the 13th
The curve that fit the past.
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