My friend Dan Buettner, author of The Blue Zones and several other important books, emailed me a rebuttal to a blog post that sought to discredit much of the findings of the Blue Zones project and subsequent work. Here it is, unedited:
A pre-print was recently posted published to a pre-print server with the provocative headline:
“Supercentenarians and the oldest-old are concentrated into regions with no birth certificates and short lifespans.”
It has been latched onto by bloggers and even some reputable outlets as newly published peer-reviewed research. Since we’ve received so many questions about it, we felt the need to respond to a few of the biggest inaccuracies in the pre-print here.
The title and one of the claims of this preprint are:
“Supercentenarians and the oldest-old are concentrated into regions with no birth certificates.”
1. Age Verification in Blue Zones Research
Blue zones researchers did not rely on data crunching from afar. I went to all the blue zones regions with a team of researchers, demographers, and scientists to the areas themselves for age validation. We used birth certificates and cross-referenced with church baptism records or other available local records in all the international blue zones regions.
“The identification and certification of a blue zones area or group is based on demographic criteria that are country-specific and depending on available documentation and its reliability.”
The FIRST CRITERION for a blue zones region is:
“The reliability of individual longevity should be thoroughly proved and therefore the extreme ages of the oldest olds, dead or still alive should be proved based on ad hoc documentation. Without documentation like birth and death records and continuous population registration system, that reliability cannot be ensured.”
Blue Zones Criteria
An example of how vigorously data collection was in blue zones regions.
“The database developed for the present study includes all individuals born in Villagrande from 1876 to 1912. For each individual we traced the exact date at death or the proof that he/she was still alive at the date of investigation. The data was gathered from civil registers (which record all births, marriages, and deaths), parish registers and the population register (anagrafe). All information has been collected in the municipality population registration office and was cross-checked with information reported in the military register and orally reported information from any relatives of these persons. With regard to those who died outside the village, the information was recovered by using annotations on date and place of death reported in the margin of the birth certificate or transcription of the date of death in the anagrafe. For those who emigrated and for whom no death has been reported, the survival status has been verified with the municipality of current residence.”
The age validation in blue zones regions has been well-documented in both academic and popular literature:
Health and nutritional status among the oldest olds in Sardinia: evidence for geographic differences
Survival Differences Among the Oldest Old in Sardinia: Who, What, Where, and Why? Demographic Research
They really are that old: a validation study of centenarian prevalence in Okinawa.
The Nicoya region of Costa Rica: a high longevity island for elderly males
The world’s top demographers and researchers do understand the need for age validation.
Using Administrative Records and Interviewing Centenarians in the Blue Zones
2. Blue Zones are NOT Regions with Supercentenarians
Blue zones areas are not those with the most supercentenarians as the pre-print describes. The blue zones areas are places with the highest healthy life expectancy, where people reach their 90s with low rates of chronic disease, and where there is a high probability to reach 100.
The blue zones criteria are clearly laid out here:
3. Relative Poverty in Blue Zones Regions
The preprint makes this conclusion: “Relative poverty and short lifespan constitute unexpected predictors of centenarian and supercentenarian status, and support a primary role of fraud and error in generating remarkable human age records.”
Yes, certain blue zones regions like the Ogliastra cluster of villages in Sardinia are among the more remote and poorer regions of the country. They are all also places where modernization and the Western diet have been slower to take hold. Older people there walk rather than drive, eat more beans and plant foods than processed and fast foods, and they connect with their neighborhoods more than watch TV and stare at their phones.
We wanted to respond thoughtfully to the most misleading statements and assumptions in the pre-print. Any other questions or inquiries can be addressed to firstname.lastname@example.org.