Centenarians — people who reach 100 years of age in good health — are the natural model organisms for successful aging. Studying their genetics, physiology, and lifestyle patterns reveals which biological differences separate the very long-lived from the rest of the population, and which factors might be accessible to intervention.
## How Rare Is Exceptional Longevity?
Approximately 570,000 centenarians exist globally (2023 data), representing about 0.007% of the world population. Japan has the highest centenarian density; Okinawa, Sardinia, Ikaria, and other Blue Zone regions show substantially above-average rates. Supercentenarians (age 110+) number only in the hundreds worldwide. The verified longest-lived person remains Jeanne Calment of France (1875–1997), who lived 122 years and 164 days.
## The Genetic Contribution to Longevity
Twin studies estimate that genetics explains approximately 25–30% of lifespan variation — roughly one quarter, with environment and lifestyle dominating. For exceptional longevity, the genetic contribution may be higher: siblings of centenarians have a 4–10 times higher probability of extreme longevity than the general population.
**APOE**: The APOE ε4 allele is the strongest genetic risk factor for Alzheimer’s disease and is associated with earlier mortality. APOE ε2 is associated with lower cardiovascular risk and longer lifespan; it is significantly overrepresented among centenarians.
**FOXO3A**: The most replicated human longevity gene. The rs2802292 G allele and related variants have been independently associated with longevity in Japanese, German, and American cohorts. FOXO3A protein participates in suppression of insulin/IGF-1 signaling, DNA damage repair, and oxidative stress response.
**Cholesterol metabolism**: Certain CETP (cholesteryl ester transfer protein) variants that raise HDL cholesterol and reduce cardiovascular risk are more common among centenarians.
## Physiological Characteristics of Centenarians
Beyond genetics, centenarians share physiological patterns:
**Low inflammation**: inflammatory cytokines (IL-6, TNF-α) are typically lower than age-matched controls.
**Preserved insulin sensitivity**: glucose metabolism remains functional; metabolic syndrome rates are low.
**Delayed disease onset**: the hallmark of centenarian health is not just long life but late disease. Major conditions (heart disease, cancer, diabetes) typically appear in centenarians at ages 80–90 rather than 60–70, and with shorter disease courses.
**Psychological resilience**: centenarians on average show lower anxiety and depression scores and personality profiles characterized by low neuroticism and higher openness.
## Major Research Programs
The **New England Centenarian Study** (NECS, Boston University) is the largest genetic centenarian study, enrolling over 2,000 centenarians, identifying longevity-associated genetic loci, and developing a 130-SNP “longevity genetic score.” See [NECS](http://www.bumc.bu.edu/centenarian/).
**Sardinian CENTENARIO Study**: focused on Sardinian centenarians, identifying population-specific longevity variants enriched in a historically isolated founder population.
**Japanese Supercentenarian Study**: identified distinctive somatic mutation profiles in supercentenarians (age 110+) and lower-than-expected clonal hematopoiesis (CHIP), suggesting unusual robustness of hematopoietic stem cells.
For context, see [Hallmarks of Aging](https://sunqi.org/aging-biology-hallmarks-en/) and [Longevity Diet](https://sunqi.org/longevity-diet-caloric-restriction-en/). A recent thorough review is at [Nature Aging](https://www.nature.com/articles/s43587-022-00209-7).
