Landmark studies in the science of aging

The experiments that turned aging from an inevitability into a field of science.

VALREXA Biosciences · 8 min read · November 2026

1. 1935

   Calorie restriction extends lifespan in rats. Clive McCay at Cornell showed that rats fed fewer calories lived longer, launching the field of dietary restriction.

2. 1961

   The Hayflick limit. Leonard Hayflick and Paul Moorhead showed normal human cells divide a limited number of times before stopping, overturning the idea that cultured cells were immortal.

3. 1993

   A single gene doubles lifespan. Cynthia Kenyon’s lab showed that mutations in the daf-2 gene, part of the insulin/IGF-1 pathway, doubled the lifespan of the worm C. elegans. Aging could be genetically regulated.

4. 2009

   Rapamycin extends mouse lifespan. The NIA Interventions Testing Program reported that rapamycin extended lifespan in mice even when started late in life, at three independent sites. See our rapamycin report.

5. 2009

   Nobel Prize for telomeres. Elizabeth Blackburn, Carol Greider and Jack Szostak were honored for discovering how telomeres and the enzyme telomerase protect chromosomes.

6. 2009–2017

   Calorie restriction in monkeys. Two long-running rhesus monkey studies, at Wisconsin and the NIA, initially seemed to disagree. A 2017 joint analysis concluded calorie restriction improves health and survival in primates, with timing and diet composition mattering.

7. 2013

   The hallmarks of aging framework is published (updated 2023). See the 12 hallmarks.

8. 2013

   The epigenetic clock. Steve Horvath shows DNA methylation can estimate age across tissues. See biomarkers of aging.

The Interventions Testing Program

Funded by the National Institute on Aging, the ITP tests compounds for effects on mouse lifespan at three sites at once (the Jackson Laboratory, the University of Michigan and UT Health San Antonio), so results must replicate to count. Compounds that extended lifespan include rapamycin (both sexes) and several that worked mainly in males, such as acarbose, 17-α-estradiol, aspirin and NDGA. Others, including resveratrol, did not.

Sources and further reading

1. Hayflick & Moorhead 1961. Exp Cell Res (PubMed)
2. Kenyon et al. 1993. A C. elegans mutant that lives twice as long as wild type. Nature
3. Harrison et al. 2009. Rapamycin fed late in life extends lifespan in mice. Nature
4. Mattison et al. 2017. Caloric restriction improves health and survival of rhesus monkeys. Nature Communications
5. Nobel Prize in Physiology or Medicine 2009
6. NIA Interventions Testing Program

Educational content, not medical advice. Talk to a qualified healthcare professional before making changes to your health routine.