But what if you could harness a network that pumps huge amounts of air through its filters, and that has records stretching back decades? In 2015, molecular biologist Per Stenberg at Umeå University in Sweden heard about just such a possibility — a 70-year history of biodiversity, told in wisps of DNA caught on tens of thousands of filters and stored at the Swedish Defence Research Agency in Stockholm.

Makes me wonder what other useful stuff is packaged up somewhere as information by-catch with the things we knew we were looking for.