According to a prediction three scientists made in 1960, the world was due to end today.
This "doomsday" was supposed to come not with a bang or a whimper, but from too many people.
The scientists had calculated that on Friday, November 13, 2026, the world's population would grow so quickly as to be near infinite.
"Our great-great-grandchildren will not starve to death," they wrote in a paper published in the journal Science at the time.
Instead, in many countries, population decline is seen as a more serious concern than population growth.
So why was this doomsday warning wrong, and why is it still so difficult to predict population change?
The paper's authors created a mathematical formula based on fertility rates and death rates, and applied it to population estimates in the previous 2,000 years.
Their formula was on a "hyperbolic curve": It showed a world population growing at increasingly fast rates. Less and less time was needed for the population to double or triple in size.
Eventually, the formula predicted, the world's population would just shoot upwards, towards infinity, at a single moment in time.
Javier Birchenall, an economist at the University of California Santa Barbara, said there was an element of humour to the study.
