All the people: what happens if humanity's ranks start to shrink?

A study in the Lancet suggests the world's population will peak in 2064. If so, the consequences will be profound

The battle to feed humanity has been lost, Paul Ehrlich warned in his influential 1968 treatise, The Population Bomb. The world's population was growing faster than the Earth could sustain, he predicted, and catastrophe loomed. In the 1970s and 1980s hundreds of millions of people will starve to death in spite of any crash programs embarked upon now."

That doomsday message turned the entomologist into a celebrity and galvanised population control and environmental movements for years after. But another social wave gathering at the time would help prove his forecasts wildly wrong.