Since 2008, Switzerland's animal welfare ordinance has required that animals of social species be able to interact with their own kind. Guinea pigs are among them: according to the federal veterinary office, they must not be kept alone, and the company of a human or another animal does not count. You can still buy just one, as long as it joins a companion of its own species. The aim is to spare this highly sociable rodent from isolation.
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.