In November 2005, an independent journalist named Dan Buettner published an article in National Geographic called “The Secrets of Long Life.” The article examined the communities of Sardinia, Italy; Okinawa, Japan; and Loma Linda, USA. According to Buettner, these communities had life expectancies far longer than expected. One Sardinian town, Silanus, was dubbed a “Blue Zone” by demographers, who would mark a map with a blue pen every time they identified a centenarian, a person who is at least 100 years old. Along with listing the areas, Buettner identified daily habits that plausibly contributed to the longevity of these areas, such as staying active, finding purpose, and, best of all, drinking red wine.
The prospect of growing very old has fascinated humanity for millennia. Some notable figures in the Bible, most famously Methuselah, are known for their great age. According to popular myth, Ponce de León spent years looking for the Fountain of Youth. Today, Silicon Valley founders are injecting themselves with various compounds and dramatically altering their lifestyles to extend their lifespans.
When the National Geographic article dropped, it was easy to turn its findings into a sales pitch. Buettner, with help from demographers Gianni Pes and Michel Poulain, monetized the blue zone concept. He wrote seven books about blue zones and founded a company, Blue Zones LLC. Cities around the world paid for his consulting services. They would adopt his suggestions, follow blue zone approaches to life, and receive a Blue Zone Community certificate upon completion. Word spread. Netflix made a four-episode series called “Live to 100: Secrets of the Blue Zones.” People everywhere wondered if a few disparate communities had cracked the code.
This popularity began to draw the attention of other scholars, who immediately questioned the conclusions.
First and foremost was the provenance of the data. One of the earliest presentations ever made about blue zones was by the researcher Gianni Pes at a demography conference in France in 1999. The reaction, according to one article, was bemusement. Most other scientists weren’t convinced that individual communities in Sardinia could have a significantly higher concentration of centenarians than the rest of the island.
Detractors have a simple explanation: fraud and poor record keeping. Throughout the 20th century, war and upheaval resulted in incomplete records. Many parts of the world didn’t keep reliable birth records until the second half of the century. Some still don’t. When that was paired with the beginnings of generous welfare states after World War II, the incentive was obvious: lie about your age. If the Italian government says everyone over the age of 65 will now receive a state pension, someone who is 45 has every reason in the world to claim to be 55. Someone in their mid-thirties can just as easily say they are in their early forties. Without accurate records, this would be impossible to confirm. Decades later, voilà! People qualify for public pensions earlier than they should. Several decades after that, communities that did this have an overabundance of centenarians.
Worse yet, some of these supposed centenarians may not even exist. Once the welfare checks start coming, families have a strong financial motive to keep an elderly relative on the books after they die. This doesn’t mean a dead body propped up at the dinner table, à la “Weekend at Bernie’s.” Rather, families can bury their deceased matriarch and simply never tell the government that Grandma Rosina has passed away.
Beyond fraud, there’s also plain luck. One supposed blue zone is Ikaria, a small Greek isle in the Aegean Sea. The problem? It’s home to fewer than 10,000 people. Maybe Ikarians have found the secret to a longer life. Maybe they are committing pension fraud. Or maybe there are just a lot of old people there by random chance. There are hundreds of islands in the Mediterranean with small populations. Statistically, some should have a preponderance of centenarians. Some should have a dearth. Not because of healthy living or good diets, but simply through the luck of the draw.
Several years ago, a professor named Saul Newman began examining the issue. He found that after accounting for disputes about birth records, the supposed blue zones didn’t have any more centenarians than one would expect. It conveniently turned out that having unreliable birth records and having a lot of old people go hand in hand. He won an Ig Nobel for his efforts. The Ig Nobel is a tongue-in-cheek academic prize for work that “makes people laugh, and then think.”
Newman noticed something remarkable and potentially devastating to the blue zone thesis. It is widely known that wealthier populations are healthier. Richie Rich is far likelier to make it to 100 than Tiny Tim. Yet many of the blue zones have the opposite trend. The areas of Sardinia with the most 100-year-olds are poorer than average. Okinawa, perhaps the most famous blue zone, is poorer than the rest of Japan. This coincides with worse record keeping; affluent areas are more likely to have capable governments. True, this is circumstantial evidence, but proponents of blue zones need to explain how poor areas with incomplete records magically have a bunch of people in the century club walking around.
Those advocating for blue zones sometimes exhibit textbook confirmation bias. Any evidence that supports their theory is accepted at face value, while any contradictions are ignored. Whenever the charge of sloppy record keeping is leveled, supporters of the blue zone theory will claim to have used multiple sources to verify that centenarians are as old as they say they are. The problem, however, is that multiple sources are not necessarily independent of each other. Once a person’s birthdate is incorrectly listed, other sources will repeat that error. Thus, a person who has five different censuses or forms with the same age may still, in reality, only be one data point. An objective researcher would have an easier time seeing this then someone with a financial stake in the outcome.
Today, the blue zone camp is split in two. Both camps agree that Sardinia, Italy; Okinawa, Japan; Nicoya, Costa Rica; and Ikaria, Greece, are blue zones. Dan Buettner, however, includes Loma Linda, California, even though he admits it made it into the original National Geographic article only because his editor wanted an American example… which is, uhhh… quite the admission. Michel Poulain, meanwhile, considers Martinique a blue zone, while Buettner has floated adding Singapore.
The good news is that blue zones are a fantastic example of how science is supposed to work. There is some credible evidence that blue zones exist. Researchers presented their findings and began publicizing them. Then, other scientists looked at the data and reached different conclusions. Now they are duking it out, making their case to the scientific community and the public. In the next few years, a new researcher could emerge with novel evidence either for or against blue zones. Either way, progress.