In the late 1990s, Italian medical statistician Gianni Pes of the University of Sassari and Belgian demographer Michael Poulain visited communal archives in many areas of Sardinia, examining birth and death certificates. The goal of their research was to calculate the extra longevity index (ELI), defined as the number of people born in Sardinia between 1880 and 1900 who became centenarians. Each community where the rate of longevity was particularly high was circled on a map in blue ink. As the research progressed, they discovered that there was an area of the map where blue ink predominated. In 2004, the results of their research were published in the journal Experimental Gerontology, under the title Identification of a geographic area characterized by extreme longevity in the Sardinia island: the AKEA study. Since then, the areas of the world with particularly high proportions of centenarians have been known as Blue Zones.
In 2005, journalist Dan Buettner made a significant contribution to the field of longevity research with the publication of his article, The Secrets of a Long Life, in National Geographic magazine. Buettner identified five areas of the world where life expectancy is significantly higher than elsewhere:
- the central mountainous area of Sardinia, which boasts the highest rate of male centenarians in the world
- a Greek island in the Aegean Sea called Ikaria, with extremely low rates of senile dementia
- the Japanese island of Okinawa, home to the longest-lived women in the world
- the Nicoya peninsula of Costa Rica, with the second highest concentration of male centenarians
- the religious community of Seventh-Day Adventists located in Loma Linda, California, where life expectancy is significantly higher than in the U.S. as a whole
The scientific community has a strong interest in these issues, as the study of life expectancy can provide a better understanding of the most common causes of age-related diseases. The primary objective is not so much to extend the lifespan as to prolong the years of good health (the health span), delaying as long as possible an individual’s physical and cognitive decline. From the results obtained so far, it seems established that no single factor can completely explain why people in these five regions live longer and healthier lives than in other parts of the world. The phenomenon of longevity is complex, and can only be explained by taking into account a multitude of interconnected and interdependent factors. It is true that many centenarians in the Blue Zones share some factors in common, such as:
- a simple lifestyle characterized by moderation
- being physically active throughout the day
- a positive outlook on life
- an emphasis on strong social ties, with the family as the highest priority
- a purpose in life and a strong sense of duty
But each of these aspects cannot be understood without a deeper understanding of the places, values, and customs of the Blue Zones.
One cannot comprehend the Sardinian Blue Zone without understanding the dynamics of the Sardinian family, the role of women in society, and the fact that placing one’s parents in a nursing home is considered a disgrace and a cause for shame. One cannot assimilate the Sardinian Blue Zone if one doesn’t deeply understand its culinary tradition; it is reductive to discuss macronutrient proportions without understanding the culture of sharing at the table. One cannot appreciate the Sardinian Blue Zone if one doesn’t understand the symbolic value that bread has held for millennia, and the strong social cohesion generated by the ritual of breadmaking.
In this context, the Blue Zone is synonymous with a thousand-year-old local culture.
The Sardinian Blue Zone is comprised of the historical regions of Ogliastra (Villagrande Strisaili, Arzana, Talana, Baunei, Urzulei, Ulassai and Perdasdefogu) and Barbagia (Seulo, Tiana, Ovodda, Ollolai, Gavoi, Fonni, Mamoiada, Orgosolo and Oliena). It is primarily comprised of two mountainous regions with a predominantly pastoral character: the granite range of the Gennargentu and the compact limestone range of Supramonte. The Sardinian Blue Zone is unique in the proportion of male to female centenarians. In the rest of the world, women strongly predominate among the centenarian population. However, in Sardinia, one finds the opposite: this is the only example of a region where the proportion of male centenarians equals, and in some cases exceeds, that of females.