Blue Zones: What Science Does and Does Not Know About Longevity

There is a map you have surely seen: the planet with five circles drawn on it — an Italian island, a Japanese island, a Greek island, a peninsula in Costa Rica, a city in California —. Where the circles fall, legend has it, people forget to die. Centenarians tend their gardens and walk down to the town square. The map has best-selling books, a successful documentary series, and an implicit promise: do what they do and the years will come on their own.

This Notebook exists, among other things, to take a slow look at the promises that come with a map. And this one deserves our full attention, because inside there is a better story than the legend: a proper scientific dispute, complete with demographers reviewing baptismal records in mountain sacristies, a playful award in the mix, and a final question that is not about how many years, but what to do with them.

From a blue marker to a global phenomenon

The story began in earnest. In the late 1990s, Belgian demographer Michel Poulain and Sardinian physician Giovanni Mario Pes set out to verify, town by town and document by document, the ages of the elderly in Sardinia. In 2004, they published with their colleagues, in the journal Experimental Gerontology, the AKEA study: the island's extreme longevity was concentrated in the mountainous central-eastern area, and in a way that did not seem coincidental. With an added rarity: men there lived to one hundred almost as often as women — a ratio of 1.35 compared to 2.43 for the rest of the island — which is highly unusual: in the centenarian club, women always win and by far. To delineate the area on the map, Poulain used a blue marker. Hence, literally, the name.

The cultural phenomenon grew on that foundation afterwards: journalistic expeditions, the canonical list of five zones, the nine habits, the books, the documentaries, the branded diets. The brand ran faster than the data, as usually happens. But the origin was not a marketing gimmick: it was a head count.

The demographer who looked at the paperwork

In 2024, researcher Saul Justin Newman received the Ig Nobel Prize in Demography — those awards honoring research that first makes you laugh and then makes you think. He won it for detective work: instead of traveling to the legendary islands to measure olive oil, he stayed in the archives, cross-referencing the world's age records with the quality of the registers where they are kept.

What he found is unsettling. In the United States, 82% of supercentenarians — people aged 110 or older — are recorded as born before their state officially registered births; when the birth certificate was introduced, the state's supercentenarians fell by around 80%. In Japan, a 2010 official audit revealed that some 230,000 centenarians on the registers were actually missing, dead, or pure clerical error. And a pattern repeated country after country: extreme age records are abundant precisely where there is more poverty and poorer record-keeping. Even the coordinates of the legend were affected: according to his calculations with European data, Sardinia and Icaria occupy average, not stellar, positions in the actual longevity of their over-85s within the European Union. His provisional conclusion, delivered with the wry smile of his trade: a good portion of the world's age records speak less of human biology than of the state of the archives and some extra pension being collected.

The response from those who counted one by one

If it ended there, it would be just another debunking. But science functions as a long conversation, and the response came through the proper channels. In December 2025, the journal The Gerontologist published a reply from gerontologist Steven Austad and Pes himself — the doctor who began counting Sardinian centenarians thirty years ago. Their argument has an elegance that is a pleasure to behold on its own: Newman is right in general; most of the world's extreme age claims are false. And precisely because of that, the recognized blue zones were validated in a way no other place on the planet has been validated.

The details are a feast for anyone who appreciates a job well done. In Sardinia, each age was verified by cross-referencing the civil registry, which has existed there since 1866, with parish archives dating back to the 17th century and a complete reconstruction of the family tree; in this way, they caught, for example, a fake supercentenarian who turned out to be the younger sister — baptized with the exact same name — of the record holder. In Okinawa, they cross-checked the declared age of each centenarian with their Chinese zodiac sign, which no one ever forgets: out of 52 checked, 49 matched the exact year. And that Japanese scandal of ghost centenarians, they add, did not find a single one in Okinawa. That same year, another academic review provided the missing picture: in fifteen towns in the Sardinian zone, 91 people out of the 18,000 born between 1880 and 1900 lived to blow out one hundred candles — triple the rate of the rest of the island —, and almost as many men as women.

Who wins? Probably both, each in their own territory. The world's registries are full of paper centenarians, as Newman says. And there are a few places where extraordinary longevity is documented with a rigor that withstands scrutiny, as Austad and Pes reply. The debate remains open in the journals, which is exactly where it belongs. Meanwhile, you are left with the lesson in methodology, which is worth more than the map: when faced with any astounding figure, the first question is not what they eat, but who counted and how.

What remains when the smoke clears

To begin with, what remains is a fact that dismantles the most fatalistic myth of all. Recent reviews estimate that genes explain less than 10% of the variation in human lifespan. Less than a tenth. The rest is environment, circumstances, habits, and chance. No one has their expiration date written in their surname.

And something else remains: the habits that long-lived communities share — eating mindfully with plenty of plants, moving every day without a gym, maintaining supportive relationships, having a purpose to get up for — do not need any island to be validated, because research on well-being arrived at them through independent paths. We have already spoken slowly in this Notebook about social connections and their weight on health, just as we have about the dimensions of human flourishing. None of those studies promise years to anyone; they describe populations, they do not sign contracts. But they all point in the same direction, and that convergence is among the most solid things that the science of well-being can offer today.

The blue zone you already live in

Here comes the twist that the legend never tells. You do not need to move to a Greek island. According to the INE — the most boring and reliable registry in existence —, life expectancy at birth in Spain reached its historic peak in 2024: 84.01 years. At age 65, a woman has, on average, more than 23 years ahead of her; a man, close to 20. Spain has been settled among the longest-lived countries on the planet for years, without a circle on the map, without a registered trademark, and without anyone selling your neighborhood's diet in an airport.

Two decades ahead, on average, with the accounting in order. The interesting question was never whether the people in the photo reach one hundred. The interesting question is what you are going to do with twenty verified years.

To live long, to live for what

Perhaps the best legacy of this entire debate is not a figure, but a gesture: that of looking at how a piece of data is constructed before believing it. That methodical curiosity — the art of observing, as called by the science stage of Thenomba's Senior travel, which devotes one module to health and longevity and another to the great laws of the cosmos — takes up no space in a suitcase and improves every journey. The program does not promise years, because no honest person can promise them: it proposes something closer at hand, which is to fill the ones we have with substance. To understand how truth is debated, to marvel at what is known and what is not, and to converse about it with people who also want to understand.

The blue circles on the map will continue to be debated in journals for years. Your time, meanwhile, is not up for debate: it is here, counted by the civil registry with a precision that the legendary islands would envy. Science, when it is honest, cannot tell you how long it will last. It can tell you, and it does so with remarkable persistence, that what you do with it — with whom, for what, looking at what — is where the game that truly matters is played.

Cover image generated with artificial intelligence.