Interesting article in the Economist about the "supercentenarian hotspots" (aka the famous "Blue Zones"). But a new study raises an important reason for skepticism.
Paywalled, but a few points:
Places claiming to be centenarian hotspots may just have bad data
A correlating bit of evidence is that between 1841 and 1919, all the US states introduced a requirement for birth certificates, "making age estimates more accurate and fraud more difficult."
https://www.economist.com/graphic-detail/2023/09/28/places-claiming-to-be-centenarian-hotspots-may-just-have-bad-data
Paywalled, but a few points:
Places claiming to be centenarian hotspots may just have bad data
clusters of high reported longevity tended to occur in areas where record-keeping might conceivably be more lax, or where residents might have more incentive to claim pensions fraudulently
...
There were also curious paradoxes in the distribution of centenarians that could be easily explained by reporting errors. In Italy provinces where more people reach the age of 105 tend to have more people die before 55. On the island of Sardinia, renowned for its abundance of very old people, residents have among the lowest chances of reaching midlife of any Italians.
A correlating bit of evidence is that between 1841 and 1919, all the US states introduced a requirement for birth certificates, "making age estimates more accurate and fraud more difficult."
aligning data on the numbers of old people in each state with the date that birth registration was introduced, Dr Newman found that it resulted in a 69% drop in the prevalence of supercentenarians.
https://www.economist.com/graphic-detail/2023/09/28/places-claiming-to-be-centenarian-hotspots-may-just-have-bad-data