We know this partly also because when countries introduced mandatory birth registration, there was a sudden drop in people who lived beyond 100 years old. Here'

We know this partly also because when countries introduced mandatory birth registration, there was a sudden drop in people who lived beyond 100 years old. Here's a paper from earlier this year on this: "Supercentenarian and remarkable age records exhibit patterns indicative of clerical errors and pension fraud" Saul Justin Newman https://www.biorxiv.org/content/10.1101/704080v3 https://www.biorxiv.org/content/10.1101/704080v3