The extra years came from fewer early deaths, not slower aging
The clearest way to see the mismatch is to separate two things people often blend together: how long someone lives on average, and how fast the body deteriorates once aging begins. Across 39 human and nonhuman primate populations spanning seven genera, longer life expectancy went hand in hand with fewer early deaths, not with a slower rate of aging [1][5]. In other words, a population can gain years mostly by getting more individuals safely into adulthood and middle age.
That pattern matters for the question. If most of our recent longevity gain is a drop in premature mortality, then we are not so much outrunning our design as finally surviving long enough to reach its later stages. The same primate comparison found that variation in the rate of aging within genera is orders of magnitude smaller than variation in pre-adult and age-independent mortality, which is a technical way of saying the clock itself barely moves while the number of people who reach old age changes a lot [1][5].
Why the aging clock is hard to reset
The 'invariant rate of aging' hypothesis holds that the pace of aging is relatively fixed within a species. The primate datasets support it: when researchers modeled changes in the rate of aging, those changes produced striking, species-atypical mortality patterns, unlike the ordinary variation seen in early-life mortality [1][5]. The implication is that the rate of aging is not a free dial we can simply turn down, even if we can keep more people alive to experience it.
A separate analysis of genetic interventions reaches a similar conclusion from a different direction. It proposes that targeted gene repair could raise disease-free healthy lifespan to roughly 110–120 years and maximum physiological lifespan to about 150 years, while systemic epigenetic resetting is theorized to reach far longer [3]. But it argues that a network of constraints, including cancer trade-offs, unavoidable DNA replication errors and non-regenerable neurons, permanently blocks unlimited extension [3]. These are modeled projections rather than demonstrated outcomes, so they are best read as an argument about where ceilings might sit, not a measurement of them.
The mismatch is most visible after menopause
The grandmother hypothesis offers a concrete case of living past what our biology was tuned for. It proposes that menopause evolved under ancestral conditions of high early mortality and short lifespans, where postmenopausal survival was brief and the consequences of estrogen loss were rarely felt for long [2]. Modern medicine, nutrition and public health changed that: women now commonly live three decades or more past reproduction, often in social settings with less reliance on kin [2].
That extended post-reproductive lifespan is where the mismatch becomes physical. The review argues that prolonged estrogen deficiency exacerbates cardiovascular, metabolic, skeletal, autonomic and neurocognitive vulnerabilities that were likely of limited consequence ancestrally [2]. This is a proposed evolutionary explanation rather than a proven cause of modern disease patterns, but it illustrates the general point: the added years are real, and the body's hormonal design was not built to run this long without them.
Can we close the gap between lifespan and healthspan?
If the rate of aging is largely fixed, the practical target shifts from extending life to making the extra years healthier. The gene-repair analysis frames this as raising disease-free healthy lifespan rather than chasing immortality, and it treats the biological constraints as permanent features to work around rather than obstacles to eliminate [3]. The menopause review makes a parallel case, suggesting that targeting ovarian-cardiovascular aging or related pathways could better align healthspan with lifespan [2].
There is also a broader evolutionary angle. One analysis of past evolutionary tradeoffs argues that constraints shaped by natural selection can sometimes be reversed, and that doing so represents an opportunity to improve human lifespan [4]. That is a hypothesis about possibility, not a demonstration that the aging rate has been slowed in people. Taken together, the evidence supports a careful answer: we are living longer than our bodies were built for, and the most realistic near-term gains lie in keeping those added years healthy rather than in resetting the underlying clock [1][2][3].
Sources used in this answer
The long lives of primates and the ‘invariant rate of ageing’ hypothesis
Across 39 human and nonhuman primate populations, variation in the rate of aging within genera is orders of magnitude smaller than variation in early and age-independent mortality, supporting biological constraints on slowing human aging.
The Grandmother Hypothesis: A perspective from cardiovascular aging
Modern longevity creates an evolutionary mismatch in women, whose extended post-reproductive lifespan exposes them to prolonged estrogen deficiency and elevated cardiovascular and metabolic risk.
Research on the Lifespan Limit of Humans Intervened by Gene Repair Technology —A Comparative Study on the Aging Mechanisms of Organisms with Near-Immortality in Nature
Gene repair is projected to raise healthy lifespan to 110–120 years and maximum physiological lifespan to about 150 years, but cancer trade-offs, DNA replication errors and non-regenerable neurons are argued to make absolute immortality impossible.
Past evolutionary tradeoffs represent opportunities for crop genetic improvement and increased human lifespan
Past evolutionary tradeoffs may represent opportunities for genetic improvement that could increase human lifespan.
THE LONG LIVES OF PRIMATES AND THE ‘INVARIANT RATE OF AGING’ HYPOTHESIS
Primate data show longer life expectancy is associated with fewer early deaths rather than a lower rate of aging, suggesting biological constraints on how much human aging can be slowed.