Lifespan

Definition

Lifespan is the total length of time an organism lives, from birth to death, and can refer to an individual or a species-typical range used in gerontology and demography. [1]

Average vs Maximum

Average lifespan (life expectancy) reflects typical survival in a population shaped by environment and healthcare, while maximum lifespan reflects the longest observed survival under optimal conditions and is often used to infer intrinsic ageing limits in humans (approximately 120-125 years). [2]

Use in Research

Lifespan is a common endpoint in ageing studies (for example, dietary restriction experiments), but it does not capture quality of life or functional capacity, which is why healthspan measures are used in parallel. [3]

References

1. Baylor OpenBooks. Lifespan, life expectancy, and healthy aging. https://openbooks.library.baylor.edu/lifespanhumandevelopment/chapter/22-1-lifespan-life-expectancy-healthy-aging/
2. ScienceDirect Topics. Lifespan. https://www.sciencedirect.com/topics/medicine-and-dentistry/lifespan
3. Austad, S. N., & Fischer, K. E. (2011). Aging and longevity. Journal of Nutrition in Gerontology and Geriatrics. https://pmc.ncbi.nlm.nih.gov/articles/PMC3257745/