William the Conqueror undertook a remarkably modern project. In 1086, he began compiling and storing a detailed record of his realm: of where everyone lived, what they did and where they came from. 900 years later, the BBC began its own Domesday project, sending school children out to conduct a community survey and collect facts about Britain. This was a people’s database, two decades before Wikipedia. But just a few years later, that interactive digital database was totally unreadable, the information lost. We tend to take archives for granted — but preservation doesn't happen by accident; digitisation doesn’t mean that something will last forever. And the erasure of the historical record can have disastrous consequences for humanity... For a full list of sources, please see the show notes at timharford.com. See omnystudio.com/listener for privacy information.