Using the national definitions compiled by the UN, the urban share of the world's population rose from about 30% in 1950 to over 55% today, with the tipping point around 2007. The UN projects close to 70% by 2050. Around 1800, fewer than one person in ten lived in a town or city: in two centuries, humanity changed its habitat.
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.