Longevity

Longevity refers to the length and quality of human life. It is usually discussed in terms of lifespan (the duration of life from birth) and healthspan (the portion of life spent in good health). In human populations, average life expectancy has risen over the past century due to reductions in infectious disease, better nutrition, and medical advances, while maximum human lifespan remains around 120–125 years, with Jeanne Calment widely cited at 122.

Determinants: Lifespan is influenced by genetics (heritability estimates for lifespan around 20–30%) and a wide range of modifiable and environmental factors, including smoking, physical activity, diet, body weight, alcohol use, sleep, stress, social ties, healthcare access, and socioeconomic status. Gene–environment interactions shape disease risk and aging trajectories.

Biology: Aging involves cumulative cellular and molecular damage, telomere shortening, genomic instability, mitochondrial dysfunction, and cellular senescence. Competing theories explain aging via damage accumulation or altered signaling pathways. Interventions under study include caloric restriction, which extends lifespan in various species, and pharmacological approaches such as metformin, rapamycin, and senolytics, with ongoing research in humans. Regular physical activity, a balanced diet, adequate sleep, and avoidance of tobacco are associated with longer healthspan and often longer life.

Measurement and policy: Researchers use epidemiological data to estimate life expectancy and disability-free life expectancy. Societal implications include aging populations, pressure on healthcare and pension systems, and considerations of equity in access to longevity-enhancing interventions and healthy environments.