Ikaria—The Island of Mysterious Longevity

Aerial photograph of Ikaria island in Greece.
The north side of the island of Ikaria, where inhabitants live longer than the south side.

Why do the inhabitants of this tiny Greek island live so long? It may be something in the rocks.

Almost every ancestor of Alekos Pylaras has lived past 100. His aunt Despoinou died at 125. “If you had come to Ikaria two days earlier, you would have met my other aunt, Xeni. She was 107,” he tells me. 

“Perhaps you should speak to Theofilos,” he says. Theofilos is 98 or 100, dons smart suits, and flirts. “Wait, he is only 97,” suddenly remembers Pylaras, who is 75, and looks not a day older than 60. He eventually introduces me to Spyridoula, who is nearly 100, reads Dan Brown novels, discusses individualism, knits sweaters, and will probably surpass in longevity her grandma Violetta, who made it to 105. 

Forty miles off the European coast of Turkey, in Greece’s eastern Aegean Sea, there is an island named Ikaria where, if you are in your 30s, you’re still a child, and if you are in your 90s, even then you could have a long road ahead. Living to 100 is commonplace on Ikaria, and one in three inhabitants lives past the age of 90. Because of this, the island is considered a world “blue-zone”—a designation for places of exceptional longevity, and one of only four across the globe. 

The island is the subject of research that the National and Kapodistrian University of Athens and Harokopio University in Athens started 11 years ago. Titled simply “Ikaria Study,” the longitudinal survey seeks to shine a light on the reasons behind these people’s extraordinary lifespan. To this end, a team of trained cardiologists and physicians regularly visit the island, monitoring the pathological and cardiological health of over 1,400 permanent inhabitants aged between 30 and as-old-as-it-gets, and studying more than 300 clinical, psychosocial, dietary, environmental, and biochemical parameters. The initial results have thus far been in equal parts predictable and counterintuitive. Physical activity, diet, and non-destructive habits, such as avoiding smoking and embracing mid-day naps, seem to power the famed Ikariot longevity, as they would anywhere else. But researchers are also calling the global scientific community’s attention to a more “silent” contributor to human vitality’s secret sauce, which is none other than the… granite rock?!

Coffee, sex, and centenarians

Ikariots swing local in their eating habits. Their typical weekly menu reads like a how-to guide for the popular Mediterranean diet: Olive oil 5–7 times a week, fruits and vegetables 4–5 times per week, fish twice, meat once, and a cup of coffee and a glass of wine on either end of their day—essentially moderation as a form of cultural expression. Eighty-five percent of the island’s residents engage in moderate physical activity, taking long walks or working the fields. Half of them observe religious fastings, requiring long periods without eating meat and dairy at certain times of the year, and most take a midday siesta. Men between 65 and 99 report at least moderate self-confidence during sex, and depression is somewhat exotic. 

Average Ikariots also share strong communal bonds and a disregard for money, even tourist money (a shocking contrast to other Greek islands like Mykonos, 90 minutes away by ferry, which is marketed as a hotspot for billionaires and the upper crust). Ikariots throw themselves into their world-renowned “panigiria,” which are traditional feasts that celebrate the name days of Christian Orthodox saints or other religious holidays and take place all around the year. Most of them, particularly the older generation, have not attained higher education. 

Spyridoula, almost 100, aims to surpass in longevity her grandma Violetta, who made it to 105. Stav Dimitropoulos

But not all Ikariots enjoy the same degree of longevity. Data from the ongoing study shows that people living in the northern part of the island outlive those inhabiting the southern part, and therein lies the mystery. Presumably southern Ikariots have no significant dietary differences from their northern counterparts—nor would genetics make sense, since there’s little chance of finding genetically isolated populations on a small island. That’s why some experts have proposed one possible reason for this discordant longevity—geology. 

Hard rocks and low doses

The north and northwest of the island are predominated by granite rocks, which naturally contain trace amounts of uranium and are known to emit very low doses of gamma radiation, between 0.20 and 3.31 millisievert annually—somewhere in between the amount of radiation you would absorb from a single chest X-ray and a more-powerful CT scan. 

“To the south of the island, on the contrary, limestone predominates,” says Christodoulos Stefanadis, professor of cardiology at the National University of Athens and the Ikaria study’s head researcher. Statistically, people in the north of the island live significantly longer than those to the south. In 2001, the northern part of the island had 11 male and 22 female nonagenarians and centenarians out of a total of 1,452 male and 1,359 female inhabitants—whereas only five out of 1,691 men and 19 out of 1,710 women were over 90 in the southern part. 

Stefanadis says this appears to be tied to the excess in gamma rays in the north, which are between 0.20 and 3.31 millisievert annually (over and above a universally “normal” amount of gamma rays would be about 1 to 2 millisievert per year). “This radiation difference is an independent prognostic factor of longevity,” Stefanadis says, though he is quick to add there is not enough evidence to confirm this definitively, simply because the question has not been properly investigated.

Before you rush out and expose yourself to gamma rays, you should know that this theory is, not surprisingly, a controversial one because it challenges a widely held scientific paradigm of how high-energy radiation is linked to cancer at low doses. Gamma rays are a very high-energy form of radiation, more powerful than X-rays. They can penetrate skin, internal tissues, bones, and even teeth—sometimes with ravaging effect. Just like X-rays, high doses of gamma rays can “ionize” or damage DNA, generate gene mutations, and cause cancer. 

But what about gamma rays at low doses? 

Rocky Mountain low

There is a widely held paradigm in the field of radiobiology called the “linear no-threshold model,” which basically says that the excess risk of cancer is cumulative with dose—meaning there is really no safe amount of radiation. But the linear no-threshold model is itself controversial because there are no long-term studies of the risk of cancer from tiny doses of ionizing radiation. What the linear no-threshold model does is to take the observed outcomes of people who have been exposed to high-dose radiation and extrapolate cancer risk for low-dose exposures—all the way down to zero radiation, zero excess risk. 

A 2021 study published in the journal Biogerontology collected data on the life expectancy, cancer-adjusted mortality, and background radiation for the entire U.S. population and found, surprisingly, higher life expectancies in places with slightly higher but still low background levels of ionizing radiation (electromagnetic waves or subatomic particles with enough energy to liberate electrons from molecules and damage DNA). 

Their younger appearance is what seems to predict whether they will live longer.

The study concluded that exposure to low-level radiation (between 0.97 and 2.27 millisievert per year) has clear health benefits in humans. This dumbfounding reconsideration of the (very small-scale and background) radiation narrative was first suggested in 1998, when three Western Rocky Mountain states (Colorado, Idaho, and New Mexico), which have 3.2 times higher annual radiation levels compared to the Gulf states of Louisiana, Mississippi, and Alabama, were found to have 1.26 times lower cancer mortality than their coastal cousins. 

“Small doses of radiation may not be harmful and are not associated with degenerative diseases of the human body, such as cancer and aging,” says Stefanadis. It is not a given that something speculated to be safe confers health benefits though, let alone increase one’s years on Earth. Could these tiny doses actually have a health benefit? “We are observing this exciting phenomenon and will soon have more data.”

Not everyone agrees. Siegfried Hekimi, a biology professor at McGill University who was not involved in the Ikaria study, says he is impressed not only by the fact that Ikariots live longer, but that they also look much younger—something I tell him I witnessed with my own eyes. Their younger appearance is what seems to predict whether they will live longer, he says. 

As we get older, he explains, we are ravaged by the loss of homeostasis, the ability of our body to restore a functional, stable, internal environment. “This gradual loss is also what kills you when it becomes very severe at an old age,” says Hekimi. When people look young for their age, it means their rate of loss of good homeostasis is slower than average, he continues. “Which suggests it will take a longer time for the processes to be so degraded that they will kill you. Thus, the logical conclusion is that, on average, people who look good for their age will live longer than people who look worse at the same age.” Hekimi finds it biologically unlikely that background radiation has anything to do with it—and scientifically unlikely we will ever know for sure.

“People, compared to shorter-lived or smaller animals, can handle radiation quite well,” he says. “A profound biological reaction to a type of rock doesn’t make much sense.” He suggests all these radiation and longevity intersection studies show positive and negative correlations or associations, rather than concrete, demonstrable evidence of a biological mechanism. “You have a hypothesis you cannot really test,” he says. “Are you going to make people live in granite caverns?” 

A photograph of the port of Magganitis, southern Ikaria.
The port of Magganitis, southern Ikaria, is one of the very few spots in the south of the island where granite rocks are found. Stav Dimitropoulos

There may be various other reasons behind these survival discrepancies between northern and southern Ikariots. “Maybe there is a genetic difference, maybe they have a different ancestry,” Hekimi says. He says because the Ikaria study reveals correlation rather than causation, “It’s like you saw something happening in the north versus the south, and now you are looking for an explanation.” As far as the 1998 Rocky Mountain study is concerned, Hekimi says 1.26 times less cancer mortality is a very small effect, and even though it’s statistically significant, it could be accounted for by any number of the hundreds of differences between these six states. 

And David Sinclair, a geneticist and co-director of the Paul F. Glenn Center for Biology of Aging Research at Harvard Medical School, says that the cancer risk of the commonly encountered or protracted radiation exposure is still debated. “Epidemiological studies that explored the cancer risk associated with low-level radiation exposure did not find any statistically significant differences in all cancer mortality between control and high natural radiation area,” he says. 

Based on that, he warns, “People should be careful not to infer that radiation is good for you or could protect you from cancer.” 

Other experts caution that the effect may not even be that noteworthy. “If you told me people in Ikaria live twice as long as on the nearby island, I would be very impressed. But we are talking about just a few years longer when we’re already living that long,” Hekimi says. “These are small changes over to the baseline.”

An island’s sun-baked secrets

Still, there’s something about Ikaria that’s exciting and relevant because of the promise of discovering and verifying the actual cause of its higher longevity in the north—whether or not it can be accounted for by the controversial hypothesis tying it to radiation from the island’s rocks. 

In 1841, the average baby was predicted to make it to 42. A person born anywhere in the world in 1960 could expect to live to 52.5. Today, the average person born in a developed country such as the United States would easily make it to 77.8, and there are some 500,000 centenarians alive today. By 2050, the Earth will be peopled by nearly 3.7 million centenarians. And while a study that ran in Nature Communications last May says 150 years may be the human lifespan’s upper limit, most studies have suggested 120 or 130 as the upper limit. 

As we seek ways to enable more and more people approach these limits, lessons from longevity pockets like Ikaria and other places may be important first steps toward cross-correlating background radiation exposure to clinical health outcomes, says Jorge Sanjurjo Sánchez, an associate professor at the University Institute of Geology Isidro Parga Pondal and the University of A Coruña in Spain. 

In countries like Germany and Austria, radon “baths” inside abandoned mines are actually covered by health insurance.

“In areas of Japan where they eat fish and shellfish with high contents of uranium and high exposure to other radioactive elements, longevity is high,” says Sanjurjo Sánchez. He also points to the province of Ourense, in the autonomous community of Galicia in northwestern Spain, where there are very high levels of gamma radiation and radon. Radon is a naturally occurring radioactive gas found mostly in rocks and is a major cause of lung cancer, and yet Ourense “has one of the highest longevity rates in the world,” he says (there are 252 centenarians per 100,000 inhabitants in Ourense). 

Because of that, Sanjurjo Sánchez thinks the Ikaria study should not be limited by only focusing on gamma radiation and should consider other types of radiation as well, especially radon. Interestingly, in countries like Germany and Austria, radon “baths” inside abandoned mines reclaimed as therapeutic radon health spas are not seen as alternative treatments but are actually covered by health insurance). 

Another issue is that the island is also a sun-baked Mediterranean one with a mild climate. “It would be useful to see what happens in other areas where radon can be a problem, such as Finland, where there are regions with high rates of radon, but because of the cold climate people spend more time indoors,” he says. 

But if we do continue studying radiation and its medical effects, Sanjurjo Sánchez believes it should be on a case-by-case basis and always in conjunction with all the other factors that could affect longevity, namely the social, cultural, climatic, dietary, and genetic factors at play. 

Of the thousands of tourists visiting Ikaria each year, few have failed to ask why the island’s inhabitants live so long, muses Pylaras. Perhaps the answer is stress—or the lack thereof. Perhaps it’s diet, perhaps genetics, perhaps some completely unknown factor, or maybe it’s a combination of all of them. 

As he gives me a tour of the island, he pulls over several times and buys fruit from a local vendor at a nonchalant, somewhat-annoying-for-someone-with-deadlines pace. As much as they are famous for being genetic outliers, so are Ikariots notorious for “taking their time” to complete the simplest of tasks. They seem to know they are spoiled with time, and they milk it. At the same time, the islanders exhibit a generously authentic and laid back approach to new faces and to just about everything. Pylaras invites me to a family dinner with roasted, fresh fish—only moments after he meets me. 

Perhaps when life stops being a sprint, time becomes an ally rather than an enemy. Pylaras certainly gets it. His T-shirt says “Life is better lived slower.”

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