It's the 'Flynn effect', named after New Zealand researcher James Flynn: in many countries, raw IQ test scores rose by about 3 points per decade during the 20th century, forcing tests to be re-normed regularly. More schooling, better nutrition and more stimulating environments are the leading explanations. In several rich countries the trend seems to have stalled, or even reversed, since the 1990s.
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.