According to her family, the oldest Frenchwoman alive, Eudoxie Baboul, aged 113, owes her longevity to cassava semolina. From genes to the environment, via psychology and lifestyle, a breakdown of what increases a person's chances of living for a century.

In 50 years, France could have 200,000 centenarians, or 60 times more than today according to the National Institute of Statistics and Economic Studies.

For the last dozen years, scientists have been focusing on their singularities, dissecting their diets, genes and lifestyles in order to discover the secrets to their longevity.

The hereditary transmission of a longevity gene has long been studied. Bradley Willcox, an Investigator at the Pacific Health Research and Education Institute (PHREI) in Hawaii, in a study published in the PLOS ONE journal of May 7, 2014, discovered a gene called FOXO3A of which one variety can double or triple the probability of its carrier living past 100.

Another American study, published in the PLOS ONE journal of January 18, 2012, focused on the DNA study of several centenarians. Thanks to statistical analyses, it identified 281 gene sequences associated with long life. These sequences modify the function of around 130 genes, of which some are associated with diseases linked to age, such as Alzheimer's, dementia and cardiovascular pathologies.

Diet and lifestyle

The oldest generations share a common trait in that they have exemplary diets light in fat, salt and animal proteins but rich in fruits and vegetables that are high in fiber and antioxidants, which protects them from cardiovascular diseases and most cancers. The Mediterranean diet, a perfect example of this, is practiced by many centenarians in "blue zones" (a geographic area of the world where people live measurably longer lives).

A serious reduction in caloric intake is also proven to aid in matters of longevity. The three-quarters rule, or stopping to eat before being full, seems to be widespread.

Maintaining physical, social and intellectual activities, which have a positive effect on vascularization, is also recommended.

Psychology also plays a part

A team of American researchers from the Boston University School of Medicine specialized in geriatrics observed that in centenarians' families, individuals were generally more extraverted and less neurotic than their peers. Their study, published on April 3, 2009, in the Journal of the American Geriatrics Society, claimed that personality could have a positive influence on aging and allow for better stress management. Centenarians also tend to be surrounded by family and benefit from other close ties.

Certain gerontologists also agree with the idea that optimism helps one live longer and that the psyche plays a large role in getting to be over 100.

Okinawa, the universal model

A pioneer in this matter, the Okinawa Centenarian Study has, since 1976, studied Japanese centenarians on the Okinawa archipelago in order to try to pinpoint the factors at play in their longevity. On this Pacific island, known for being the healthiest in the world, centenarians number nearly half a million and a specialized division, the Okinawa Research Center for Longevity Science, was even created within the International University.

The center's director, Dr. Makato Suzuki, has defined five basic principles applicable to centenarians: auto-assistance (being able to self-check your health), physical health, mental health, social health and spiritual health.