My bet is blue zones are just places where they don't have good longevity records so you get a bunch of fake centenarians. That turned out to be the case in Japan: https://www.bbc.com/news/world-asia-pacific-11258071 and I think also in Greece.
People were just keeping dead relatives "alive" for the social security or rent control.
People were just keeping dead relatives "alive" for the social security or rent control.