Oral rehydration solutions, developed in the late 1960s, replace the water and salts lost through diarrhoea, with sugar helping the gut absorb sodium. In 1978, The Lancet hailed them as one of the century's major medical advances. They have helped cut child deaths from diarrhoea by more than two-thirds since 1990.
That's the estimate from a WHO-led study published in The Lancet in 2024, covering the half-century since the Expanded Programme on Immunization was launched in 1974. It works out to about six lives saved every minute, mostly infants. The measles vaccine alone accounts for around 60% of those lives.
According to the World Gold Council, about 216,000 tonnes of gold have been mined in all of human history. Because gold is so dense (19.3 tonnes per cubic metre), it would fit in a cube about 22 metres on each side, roughly the height of a seven-storey building. Strikingly, about two-thirds of it has been mined since 1950.