Will you live to 120?

Sources and Further Reading

Where to go next — the key papers behind each chapter.

This book is written as a continuous story rather than a string of footnotes, which is the right form for its purpose but leaves a debt: the claims in these pages rest on real, specific, often beautiful pieces of published science, and a reader who wants to check them, or simply to go deeper, deserves to know where to look. What follows is that map — not an exhaustive bibliography, but a curated guide to the landmark papers and primary sources each chapter is built on, the doors into the literature. Most are findable by author and year; many of the older ones are freely available, and the foundational ones are worth reading in the original at least once, because the way a discovery is first reported tells you things a textbook summary never will.

A word of method, in the spirit of the book: when you read one of these papers, ask it the same questions you’ve learned to ask the headlines. Was this in a mouse or a human? Is the result a moved marker or a changed outcome? Compared to what? What would it take to believe it? The primary literature is not sacred — it is where the arguments actually happen, including the ones that later turned out to be wrong. Reading it critically is the whole point.

Introduction and framework

López-Otín, C., Blasco, M.A., Partridge, L., Serrano, M., & Kroemer, G. (2013). The hallmarks of aging. Cell. — The paper that organized the field into the framework this book follows.

López-Otín, C., Blasco, M.A., Partridge, L., Serrano, M., & Kroemer, G. (2023). Hallmarks of aging: An expanding universe. Cell. — The updated, expanded framework.

Olshansky, S.J., Willcox, B.J., Demetrius, L., & Beltrán-Sánchez, H. (2024). Implausibility of radical life extension in humans in the twenty-first century. Nature Aging. — The central evidence behind this book’s answer to the hundred-and-twenty question: that average life expectancy in the longest-lived countries is leveling off, not climbing toward the hundreds.

Oeppen, J., & Vaupel, J.W. (2002). Broken limits to life expectancy. Science. — The optimists’ classic: record life expectancy has risen steadily for over a century, with every predicted ceiling eventually broken.

Dong, X., Milholland, B., & Vijg, J. (2016). Evidence for a limit to human lifespan. Nature. — The other side of the maximum-lifespan debate: an argued ceiling near 115–125. Read alongside the published rebuttals to see a genuine scientific disagreement in motion.

Chapter 1 — Telomeres

Hayflick, L., & Moorhead, P.S. (1961). The serial cultivation of human diploid cell strains. Experimental Cell Research. — The paper that overturned Carrel and established that normal cells count their divisions.

Olovnikov, A.M. (1973). A theory of marginotomy. Journal of Theoretical Biology. — and Watson, J.D. (1972). Origin of concatemeric T7 DNA. Nature New Biology. — The end-replication problem, identified independently.

Blackburn, E.H., & Gall, J.G. (1978). A tandemly repeated sequence at the termini of the extrachromosomal rRNA genes in Tetrahymena. Journal of Molecular Biology. — The pond ciliate gives up the telomere repeat.

Szostak, J.W., & Blackburn, E.H. (1982). Cloning yeast telomeres on linear plasmid vectors. Cell. — The experiment that proved telomeres are a universal, transferable element.

Greider, C.W., & Blackburn, E.H. (1985). Identification of a specific telomere terminal transferase activity in Tetrahymena extracts. Cell. — The discovery of telomerase (the “Christmas gel”). Blackburn, Greider, and Szostak shared the 2009 Nobel Prize for this line of work.

Jaskelioff, M., et al. (2011). Telomerase reactivation reverses tissue degeneration in aged telomerase-deficient mice. Nature. — The dramatic mouse “rejuvenation” — and a case study in why the engineered-deficiency caveat matters.

Codd, V., et al. (2021). Polygenic basis and biomedical consequences of telomere length variation. Nature Genetics. — Large-scale human genetics of telomere length, including the trade-off in which longer telomeres lower some risks and raise cancer risk.

Armanios, M., & Blackburn, E.H. (2012). The telomere syndromes. Nature Reviews Genetics. — How telomere-maintenance mutations cause premature aging in high-turnover tissues — the proof that telomeres matter in humans.

Chapter 2 — Epigenetic clocks

Horvath, S. (2013). DNA methylation age of human tissues and cell types. Genome Biology. — The multi-tissue clock: 353 sites, an elastic-net regression, near-universal across tissues.

Hannum, G., et al. (2013). Genome-wide methylation profiles reveal quantitative views of human aging rates. Molecular Cell. — The contemporaneous blood-based clock.

Marioni, R.E., et al. (2015). DNA methylation age of blood predicts all-cause mortality in later life. Genome Biology. — Age acceleration as a mortality signal.

Levine, M.E., et al. (2018). An epigenetic biomarker of aging for lifespan and healthspan. Aging. — PhenoAge: the second-generation move to training on health rather than the calendar.

Lu, A.T., et al. (2019). DNA methylation GrimAge strongly predicts lifespan and healthspan. Aging. — GrimAge: training directly on mortality.

Belsky, D.W., et al. (2022). DunedinPACE, a DNA methylation biomarker of the pace of aging. eLife. — The third-generation shift from a state to a rate.

Yang, J.-H., et al. (2023). Loss of epigenetic information as a cause of mammalian aging. Cell. — The ICE-mouse experiments behind the “information theory of aging.”

Fahy, G.W., et al. (2019). Reversal of epigenetic aging and immunosenescent trends in humans. Aging Cell. — The small, uncontrolled, much-cited TRIIM trial — the canonical “moved a clock ≠ reversed aging” cautionary case.

Zou, H., & Hastie, T. (2005). Regularization and variable selection via the elastic net. Journal of the Royal Statistical Society B. — For the reader who wants the math of the clock’s engine.

Chapter 3 — Cellular senescence

All 10 chapters of Will you live to 120? · Foundations · All courses