On Yap, in Micronesia, 'rai' are large limestone discs with a hole in the middle, quarried in Palau some 400 km away and brought back by canoe. The biggest are more than 3 metres across. They are hardly ever moved: it is enough for everyone to know who owns them. According to explorer William Furness, writing in 1910, one stone that sank during a storm was still counted as part of a family's wealth.
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.