From 1 to 120 candles. When reality exceeds life expectancy

IN BRIEF

• There is no single consensus on a precise "ceiling" for human life: demographic and statistical studies show diverse and debated results.
• Data on centenarians suggest that mortality may slow down or stabilize at very advanced ages, but interpretation is sensitive to methods and the quality of records.
• Biological mechanisms (telomeres, oxidative damage, metabolic pathways) influence aging; nutritional and lifestyle interventions can improve health and average life expectancy, but do not guarantee maximum years.
• A balanced diet, physical activity, weight control, and reduced inflammation are associated with lower mortality in the general population.

Abstract: what does science say?

The debate on the biological limit of human life revolves around three key points: demographic analyses of extreme ages, biological evidence on aging mechanisms, and observational data on lifestyles and health. Some studies have proposed a "ceiling" for lifespan around 115–120 years; others suggest that mortality may stabilize beyond 105 years or that there is no fixed limit detectable with current data. Molecular biology shows processes (telomeres, cellular damage, nutrient-sensing pathways) that limit cellular function over time, but this knowledge does not automatically translate into a numerical "maximum" value. Nutritional and preventive interventions reduce the risk of chronic diseases and increase the likelihood of living more years in good health; however, the strength of associations varies by context, method, and studied population. Interpretive limitations include the scarcity of verified data at extreme ages and the difficulty of inferring causality from observational studies.

The demographic debate: limits, plateaus, uncertainties

In 2016, a demographic analysis proposed that data had shown a limit to human life around 115 years, based on the historical trend of maximum age at death [1]. This statement reignited the discussion: subsequent works showed how the choice of statistical model and the quality of records can modify estimates and conclusions [2][3]. Studies on populations with detailed demographic records have described a deceleration in the growth of mortality risk at older ages and even a mortality plateau after about 105 years in some cohorts [3]. Other analysts have argued that, with the same data, there is no definitive evidence of an absolute biological 'ceiling' and that the probability of surviving beyond certain thresholds remains low but not zero [2].

Two considerations profoundly influence interpretations: the quality and verification of extreme ages (false positives or recording errors can alter results) and the size of cohorts (very long-lived individuals are numerically few, increasing statistical uncertainty). For these reasons, the scientific community uses different approaches (analysis of historical maximums, mortality models, analysis of supercentenarians) that lead to non-uniform conclusions. In summary, current demographic data do not allow for a single answer: it is possible that a very high practical threshold exists, or that the limit is so remote (or conditioned by external factors) that it is not observable with currently available datasets [1][2][3].

Biology of aging: what we know and what we don't

From a biological perspective, aging is a complex process involving the accumulation of molecular damage, metabolic alterations, loss of tissue regeneration, and immune changes. Among the most studied mechanisms are telomere shortening, oxidative stress, and the regulation of nutrient-sensing pathways like mTOR and sirtuins. Observational and experimental studies have shown that telomere length in circulating cells is associated with higher mortality and age-related diseases in elderly populations [4]. Experiences of prolonged stress have been correlated with accelerated telomere shortening, suggesting that psychosocial factors can modify these biomarkers [5].

Experimental interventions in animal models and clinical observations indicate that caloric restriction and other forms of energy limitation modulate biological pathways with favorable effects on health and, in many cases, on lifespan [6][7]. However, translating these results into recommendations for humans requires caution: the benefits observed in models do not guarantee an increase in the "maximum" human years, but rather a possibility of increasing health and average survival if applied appropriately [6][7].

A correct lifestyle, the secret to longevity

The most robust epidemiological evidence does not point to a single "longevity gene" that, alone, guarantees 120 years of life: rather, patterns of behavioral and environmental factors associated with a higher probability of living longer and in good health emerge. Quality diets, such as the Mediterranean paradigm, are associated with reduced mortality in the adult population and appear to act through multiple metabolic and inflammatory pathways [8]. Caloric restriction and controlled dietary interventions produce favorable responses on cardiometabolic risk factors, but their large-scale and long-term application requires individual and medical-scientific evaluations [6][7][8].

What it means in practice

For those seeking practical guidance, the message consistent with the evidence is geared towards risk reduction and health improvement in old age, not the promise of exceeding a numerical threshold of maximum age. Interventions that show consistent associations with lower mortality include a diet rich in vegetables, legumes, whole grains, fish, and unsaturated fats, adhering to the principles of the Mediterranean diet, which has been associated with a 20–25% reduction in the risk of death in large cohorts [8].

Regular physical activity, maintaining a healthy body weight, and controlling cardiovascular and metabolic factors (blood pressure, glycemia, cholesterol) reduce the probability of chronic diseases that shorten average life. Behavioral strategies for stress reduction, adequate sleep, and active social networks contribute to resilience and overall well-being; some of these components are also associated with more favorable aging biomarkers [4][5][6].

It is important to emphasize that much evidence comes from observational studies: they document strong associations at the population level but not necessarily certain causality for all aspects. Lifestyle choices that improve average health increase the chances of reaching old age in good condition, and this is the realistic and achievable target for the majority of people [6][8].

KEY POINTS TO REMEMBER

• There is no scientific consensus on a definitive numerical limit to human life; demographic data are subject to different methods of analysis and interpretation.
• The longest documented verified record (Jeanne Calment) remains exceptional but does not prove a universal "ceiling."
• Molecular mechanisms (telomeres, nutrient-sensing pathways) explain parts of the aging process, but do not solely determine a maximum age.
• Quality diet, physical activity, and chronic disease control reduce mortality risk and improve health in advanced years.

Limitations of evidence

It is necessary to clearly distinguish between observational studies and causal evidence: many associations related to diet and lifestyle come from cohort studies or meta-analyses that cannot directly demonstrate that a single behavior causes an increase in the maximum achievable age. Furthermore, the demographic debate on the "limit" of human life is sensitive to recording errors, selection bias, and the choice of statistical models; some analyses show a mortality plateau beyond 105 years in certain populations, while others criticize these results or use alternative models obtaining different conclusions [1][2][3].

On the biological side, the translation from animal results or biomarkers (telomeres, metabolic pathways) to human clinical practice is complex: interventions effective in experimental models do not always produce the same effects in humans, due to differences in scale, genetics, and environmental context [6][7]. Finally, the rarity of extremely long-lived individuals makes estimates of maximum age more uncertain and susceptible to the variability of datasets and demographic validation criteria [2][3].

Editorial conclusion

Modern science does not currently provide a simple answer to the question "how many years can we live?". Demographic and biological results are consistent in indicating that the possibility of living more years in good health has increased thanks to prevention, nutrition, and care, but they do not converge on a single definitive numerical limit. For the general public, the practical and evidence-based goal remains health promotion: reducing risk factors, promoting quality diets, exercising regularly, and managing chronic diseases. This approach does not promise a precise longevity threshold, but significantly increases the chances of adding years of life with good quality.

SCIENTIFIC RESEARCH

1. Dong X, Milholland B, Vijg J. Evidence for a limit to human lifespan. Nature. 2016. https://doi.org/10.1038/nature19793
2. Rootzén H, Zholud D. Human life is unlimited – but short. Extremes. 2017. https://doi.org/10.1007/s10687-017-0305-5
3. Barbi E, Lagona F, Marsili M, Vaupel JW, Wachter KW. The plateau of human mortality: Demography of longevity pioneers. Science. 2018. https://doi.org/10.1126/science.aat3119
4. Cawthon RM, Smith KR, O’Brien E, Sivatchenko A, Kerber RA. Association between telomere length in blood and mortality in people aged 60 years or older. Lancet. 2003. https://doi.org/10.1016/S0140-6736(03)12384-7
5. Epel ES, Blackburn EH, Lin J, et al. Accelerated telomere shortening in response to life stress. Proc Natl Acad Sci U S A. 2004. https://doi.org/10.1073/pnas.0407162101
6. Fontana L, Klein S. Aging, adiposity, and calorie restriction. JAMA. 2007. https://doi.org/10.1001/jama.297.9.986
7. Green CL, Lamming DW, Fontana L. Molecular mechanisms of dietary restriction promoting health and longevity. Nat Rev Mol Cell Biol. 2022. https://doi.org/10.1038/s41580-021-00411-4
8. Ahmad S, Moorthy MV, Lee I-M, et al. Mediterranean Diet Adherence and Risk of All-Cause Mortality in Women. JAMA Netw Open. 2024. https://doi.org/10.1001/jamanetworkopen.2024.14322