Critiquing the Blue Zones
The idea that there are portions of the world in which lifestyle choice is leading to a sizable increase in life expectancy for large numbers of people, known as Blue Zones, is increasingly looking to be a mirage, the result of bad data and insufficiently skeptical analysis of that bad data. People are fascinated by longevity, credulous in the face of determined marketing, and Blue Zones have expanded as a cultural concept far beyond the limited evidence for their existence. People will be selling the Blue Zone concept long after the scientific community has written it off as one of many historical errors in epidemiology.
Researchers have spent years identifying what are claimed to be methodological errors throughout the longevity literature. For Blue Zones, the main argument is that a significant proportion of supposed centenarians may simply not exist. Around 1900, when the U.S. started to issue birth certificates, the number of centenarians aged 110 or older dropped sharply - presumably because people had been misrecording their age, whether on purpose or accidentally. Similarly, after the Greek government began checking on people receiving pensions, about 70% of all alleged centenarians in the country turned out to be dead. Researches also found that some age databases contain unusual numbers of people born on the first day of the month or on dates divisible by five, suggesting many of these birth dates are fabricated.
It is no coincidence that blue zones are found in poor, remote places that may have spotty record keeping. One can further argue that the supposed healthy lifestyle of the people who live in blue zones is not always backed up by real world data. For example, out of 47 Japanese prefectures, Okinawa ranks first on body mass index, second on beer consumption, and fourth on suicide rate among people over the age of 65.
"If equivalent rates of fake data were discovered in any other field - for example, if 82% of people in the UK Biobank or 17% of galaxies detected by the Hubble telescope were revealed to be imaginary - a major scandal would ensue. In demography, however, such revelations seem to barely merit citation. What demographers call validation is actually just checking the consistency of documents. If documents are consistently wrong then errors are not detectable."
Link: https://www.science.org/content/article/do-blue-zones-supposed-havens-longevity-rest-shaky-science