← Daily DoseThe Second Lifetime — Daily Dose No. 018
Daily Dose / Aug 5, 2026 / Longevity
The Second Lifetime
For most of human history a newborn could expect fewer than thirty years. Today the global average is 73.3. Almost none of that gain came from curing old age — it came from children who stopped dying, water that stopped killing, and a syringe. In two centuries our species handed itself a second lifetime.
×2.5
Global life expectancy at birth, 1800 → 2024.
About 29 years to 73.3 years — a gain of roughly 44 years, added at an average of about 80 days of extra life expectancy for every calendar year that passed.
Sources: Riley (2005) via Our World in Data; UN World Population Prospects 2024.
01 / The line that bent
Nothing happened for millennia. Then everything happened at once.
Life expectancy barely moved between antiquity and 1800 — and it had still barely moved by 1900. Four-fifths of the entire gain arrived after 1900, and more than half of it after 1950.
Global life expectancy at birth, years · 1800–2024
02 / The spectrum
In 1800 the whole world was poor in years. Now the whole world has moved right.
Two hundred years ago no region on Earth averaged even 40 years, and the spread between the best and worst places was under a decade. Today the worst-off country lives longer than the best-off country did in 1800 — but the spread has grown to almost 32 years.
Life expectancy at birth, years · light = shorter lives, dark = longer lives
24 years5688 years
Circa 1800 — regional averages
26Africa
34Europe
35Americas
2024 — countries & world average
54.6Nigeria — lowest
73.3World average
79.0United States
84.8Japan
86.5Monaco — highest
03 / Where the years came from
Roughly half the gain is simply children who did not die.
Life expectancy at birth is an average, and averages are brutalised by deaths at age zero. Across pre-industrial societies about half of all children died before reaching adulthood. That single number, collapsing, does most of the work in the chart above.
children under five still died in 2024 — down from about 12.5 million a year in 1990. UN IGME, 2025
15% → 0.4%
babies dying before their first birthday, England & Wales, 1841 vs 2011. Office for National Statistics
≈27%
of infants died in the first year of life across historical societies studied. Volk & Atkinson, 2013
04 / The other half
But the old got older too — and that is the newer story.
The lazy version of this history says people always lived to seventy if they survived childhood. They did not. In 1841 a 65-year-old English man could expect about eleven more years; today he can expect eighteen. Since 1950, most of the added years have come from adults and the elderly, not infants.
Further years of life expected at age 65, England & Wales · scaled to 22 years
Men, 1841
10.9 yrs
Women, 1841
11.5 yrs
Men, 2011
18.3 yrs
Women, 2011
20.9 yrs
17% → 50%+
share of all deaths worldwide occurring at age 80 or older: 1995 vs projected for the late 2050s. UN World Population Prospects, 2024
+68%
increase in remaining life at 65 for English men between 1841 and 2011 — old age itself lengthened. ONS (Daily Dose calculation)
47.3 → 79.0
United States life expectancy at birth, 1900 vs 2024, in years. CDC / National Center for Health Statistics, 2025
05 / The machinery
Plumbing and needles, not miracle cures.
When economists decompose the mortality decline, the biggest identifiable levers are unglamorous: sand filters, chlorine, and vaccination campaigns. Each bar below is a published estimate of how much of a given mortality decline is attributable to one intervention.
Share of a measured mortality decline attributed to one intervention
Clean waterinfant mortality, US cities 1900–36
≈75%
Clean waterchild mortality, US cities 1900–36
≈63%
Vaccinationinfant mortality in Africa, 1974–2024
52%
Clean watertotal urban mortality, US 1900–36
≈50%
Vaccinationglobal infant mortality, 1974–2024
40%
154M
deaths averted by vaccination against 14 pathogens, 1974–2024 — 146 million of them children under five. Shattock et al., The Lancet, 2024
93.7M
of those lives saved by the measles vaccine alone — 61% of the total, the single largest driver. The Lancet, 2024
300M → 0
smallpox deaths in the 20th century, versus zero natural cases since October 1977. Declared eradicated 8 May 1980. World Health Organization
06 / The frontier
The record has risen three months a year, every year, since 1840.
Demographers have repeatedly declared a ceiling on human life expectancy, and the ceiling has been broken on average within five years of each announcement. In the longest-lived country of any given year, life expectancy has climbed by almost exactly 2.5 years per decade for nearly two centuries — a straight line, not a curve flattening out.
+2.5
years of life expectancy per decade in the world-record country, a linear trend unbroken since 1840 — about 6 extra hours of expected life per day lived (arithmetic from the published rate). Oeppen & Vaupel, Science, 2002
−1.8
years wiped off global life expectancy between 2019 and 2021, dropping it to 71.4 — erasing a decade of progress in two years. WHO World Health Statistics, 2024
77.4
years: projected global life expectancy in 2054, if the recovery holds. UN World Population Prospects, 2024
Global healthy life expectancy vs total life expectancy, 2021 · the years lived in poor health
Why it matters
The second lifetime was built, and it can be unbuilt.
None of this was inevitable and none of it is self-sustaining. The single largest life-saving technology of the last fifty years is a measles shot that costs about a dollar; the second is a water treatment plant. Both depend on institutions that have to be funded every year, forever. COVID-19 showed how fast two decades of gains can evaporate.
Keep the boring things funded. Routine childhood immunisation and municipal water treatment have better mortality returns than almost any clinical intervention ever measured.
Watch the gap, not the average. A child born in Nigeria today faces the life expectancy an American faced in the 1920s. The 32-year spread between countries is the largest remaining pool of avoidable years.
Ask about healthy years. Life expectancy is now 71.4 while healthy life expectancy is 61.9 — nearly a decade of the average life is lived in poor health. Closing that gap is the next frontier.
Distrust the ceiling. Every published limit to human life expectancy has been broken, usually within a few years of being announced.
Sources & notes
United Nations DESA, World Population Prospects 2024 — global life expectancy at birth 73.3 years in 2024 (up 8.4 years since 1995); projected 77.4 years in 2054; more than half of deaths at age 80+ by the late 2050s versus 17% in 1995; country figures for Nigeria (54.6) and Monaco (86.5).
J. C. Riley, "Estimates of Regional and Global Life Expectancy, 1800–2001," Population and Development Review (2005), via Our World in Data — global life expectancy under 30 years in 1800; regional averages in 1800: Africa 26, Europe 34, Americas 35.
Our World in Data, Life Expectancy and Twice as long — life expectancy around the world (2024 update) — long-run series and the "more than doubled" framing.
World Health Organization, World Health Statistics 2024 (24 May 2024) — global life expectancy fell 1.8 years to 71.4 between 2019 and 2021; healthy life expectancy fell 1.5 years to 61.9; hardest-hit regions lost about 3 years.
UN Inter-agency Group for Child Mortality Estimation (UN IGME), Levels & Trends in Child Mortality, 2024/2025 reports — 4.9 million under-five deaths in 2024; 1 in 27 children died before age five in 2024 versus 1 in 11 in 1990; under-five mortality down more than 60% since 1990.
A. A. Volk & J. A. Atkinson, "Infant and child death in the human environment of evolutionary adaptation," Evolution and Human Behavior (2013) — approximately 27% infant mortality and roughly 50% mortality before adulthood across historical and pre-industrial societies; the authors describe these as conservative estimates.
Office for National Statistics (UK), How has life expectancy changed over time? (2015) — England & Wales life expectancy at birth 40.2 (m) / 42.2 (f) in 1841 versus 79.0 / 82.8 in 2011; remaining life at age 65 of 10.9 / 11.5 years in 1841 versus 18.3 / 20.9 in 2011; about 15% of babies died before their first birthday in 1841 versus 0.4% in 2011.
D. M. Cutler & G. Miller, "The role of public health improvements in health advances: the twentieth-century United States," Demography 42(1), 2005 — water filtration and chlorination in major US cities, 1900–1936, account for roughly half of the total mortality decline, about three-quarters of the infant mortality decline and nearly two-thirds of the child mortality decline.
A. J. Shattock et al., "Contribution of vaccination to improved survival and health: modelling 50 years of the Expanded Programme on Immunization," The Lancet (2024) — 154 million deaths averted 1974–2024 across 14 pathogens, 146 million in children under five; 93.7 million (60.8%) from measles vaccination; 9.0 billion life-years gained; 40% of the global decline in infant mortality attributable to vaccination, rising to 52% in Africa.
World Health Organization — smallpox killed an estimated 300 million people in the 20th century; last naturally occurring case October 1977 (Ali Maow Maalin, Somalia); eradication declared by the World Health Assembly on 8 May 1980.
J. Oeppen & J. W. Vaupel, "Broken limits to life expectancy," Science 296:1029–31 (2002) — best-practice (world record) life expectancy has risen almost linearly by about 2.5 years per decade since 1840.
CDC / National Center for Health Statistics — US life expectancy at birth 47.3 years in 1900; 78.4 in 2023; 79.0 in 2024 (Mortality in the United States, 2024).
NOTES ON THE NUMBERS. The 1800–2024 trend line splices sources: values before 1950 are historical estimates reconstructed from parish, census and skeletal records and carry wide uncertainty; 1950 onward is UN WPP 2024, with the 2019 and 2021 points taken from WHO. "Pre-industrial ≈50%" measures deaths before adulthood, a different (and larger) metric than the under-five rates beside it — the comparison is indicative of scale, not a like-for-like series. The "6 extra hours of life per day" and "+68% at age 65" figures are Daily Dose arithmetic derived from the published rates cited above, not separately published statistics. The share of the total life-expectancy gain attributable to falling child mortality varies by period and region; roughly half is a widely used approximation, not a single measured value.