In medieval chess, inherited from the Persian game, the piece beside the king was the 'fers' or vizier, an adviser that could move only one square diagonally. Towards the end of the 15th century, in Spain and Italy, it became the queen and gained its modern powers: moving as many squares as it likes in a straight line or diagonally. The change made games far faster and marked the birth of modern chess.
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.