The Perils of Human Longevity

What would society be like if humans could live to be 200 years old?

The Fountain of Youth, Lucas Cranach the Elder (1546)

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I: The Immortal

Right now, in the frigid waters of the Arctic Ocean, there is a shark swimming who was born sometime between 1513 and 1753—roughly between the reign of Henry VIII and the birth of Alexander Hamilton. Lurking in the vast expanse of waters frozen in temperature and in time, it survives, likely oblivious to the existence of our species or the dramatic social change we have undergone during its sprawling lifespan. The good news for that elderly Greenland shark is that, unlike us, it need not save for retirement.

Humanity, throughout its history, has been dazzled by the prospect of immortality. The oldest written story in the world, the Epic of Gilgamesh—preserved in beguiling clay tablets—recounts Gilgamesh’s fear of his own mortality, triggered by the premature death of his friend Enkidu. After enduring a doomed quest for immortality, Gilgamesh recognizes that the finite period of life imbues existence with meaning.

Qin Shi Huang, the first emperor of China, was said to have believed in the power of consuming mercury to confer immortality (this belief did not serve him well). Charles-Édouard Brown-Séquard, a pioneering Mauritian scientist, claimed to have restored his youthful sexual prowess in his 70’s after repeatedly injecting bits of animal testicles under his skin. And Diane de Poitiers, 16th century noblewoman and mistress to a French king, reportedly liked to drink an elixir that would keep her young, concocted from liquid gold. (Modern testing on hair from her remains showed concentrated traces of gold, implying that she likely died from the drink that she hoped would make her forever young).

No matter how much we search for the Fountain of Youth or the Peaches of Immortality, we have not—and likely will not—master the secrets of Turritopsis dohrnii, the immortal jellyfish that can repeatedly reverse aging and return to its juvenile incarnation. Despite Netflix hype, quack doctors cashing in on promises of miracle lifespans with simple lifehacks, and longevity guru weirdos cloaked in the secrecy of non-disclosure agreements, we have slowed, not stayed, death’s scythe.

And yet, the seductive allure of immortality is not one of longevity at all costs. Few yearn to be disembodied brains, kept alive by pulsating machines and endless serums, nor do we wish to persist endlessly in a hospital bed, our minds obliterated with disease and our tired bodies aching. What many want is a prolonged healthspan, which refers to the length of time that our bodies remain in good physical health.

Healthspan is markedly different to both lifespan and life expectancy. Lifespan refers to the maximum amount of time a human can live, whereas life expectancy is the average period a human can expect to live from birth. If you have a group of 100 people and one of them lives to be 100, then the lifespan for that group would be 100. By contrast, the life expectancy would be the average age of death among those 100 people. If half of that population died in infancy, those early deaths would skew the life expectancy considerably, but leave lifespan unaffected.

Contrary to popular belief, human lifespan has increased over millennia, but perhaps not drastically so. Pliny the Elder, writing in the first century, catalogued a series of outliers who allegedly made it to the age of 100. (Some claims are far more outlandish; Old Tom Parr was said to have lived for 152 years before he died in 1635. An autopsy was performed, which found his organs to be in remarkable condition, most likely because he was actually below 70 years old).¹

While ancient records of age are notoriously unreliable, harder archaeological evidence does seem to suggest that lifespan has been comparatively stable. In other words, a lucky few ancient Romans probably were living into their 80s and 90s, even as vast numbers of children, women in childbirth, hard laborers, and those struck down by disease, all died tragically young.

As medical advances and public health have improved, however, life expectancy has surged—with a significant spike beginning in the early 20th century. The below chart, from Our World in Data, illustrates how far we’ve come.

Even in Africa, which lags behind the rest, life expectancy was just 26 years in 1925; today, it’s 64, an astonishing improvement in just one century. And, for most people in high-income nations, those born 100 years ago could expect to live an average of 30 years shorter lives than those born now. As a recent paper in Nature Aging puts it: “this historic event began with reductions in early age mortality and continued later in the twentieth century with mortality improvements at middle and older ages.”

The most significant initial improvement to life expectancy came from the reduction of children who die young. The horrifying chart below makes clear that for most of pre-20th century history, roughly 4 in 10 kids died before they reached their fifth birthday. (It was therefore a relatively typical experience for parents throughout history to bury at least one child). The slope of the child mortality line from the mid-20th century to today is a statistical artefact of one of the most gargantuan reductions in human suffering ever achieved.

Public health interventions and medical advances have also more recently reduced mortality across the aging spectrum, from middle age to the elderly. This provoked the obvious optimism: what if these improvements just keep coming? Are we on an unstoppable scientific quest, that, unlike Gilgamesh’s doomed attempt, could end with extreme longevity if not immortality?

The problem, as researchers in Nature Aging recently proved, is that the low-hanging fruits have already been plucked. In other words, outside the poorest countries, the knocks to life expectancy that come from the most easily solved sources (such as high levels of childhood mortality) have already been mostly fixed. Any significant life expectancy gains would have to come by prolonging life in the elderly who are already reaching the known limits of lifespan. (The Frenchwoman Jeanne Calment, who died in 1997 at the age of 122, is the oldest person to ever live. Despite all the medical advances in the last quarter century, nobody has surpassed that record).²

After a rapid surge, “since 1990, improvements overall in life expectancy have decelerated.” There are now diminishing returns—and public health provision and medical advances are unlikely to fulfill optimistic dreams of humanity steadily marching toward the longevity of a Greenland shark. There may be an absolute limit of a natural human life. The lead author of the Nature paper used an athletics analogy to explain this for The New York Times:

“Could someone run a two-minute mile? No. The human body is incapable of moving that fast based on anatomical limitations. The same thing applies to human longevity.”

To extend that sports analogy, existing improvements to life expectancy have been like steady incremental improvements toward a finite limit, chipping away at faster miles but with diminishing returns. Roger Bannister became the first human to run a sub-4 minute mile in 1954; 71 years later, the record is stuck at 3 minutes and 43 seconds. If we want to get down to two minutes, our basic physiology would need to radically change.

That may be possible for aging. Some promising research aims to slow biological aging altogether, changing the underlying cellular mechanism of how we age. (One prominent expert believes that, theoretically, biological technologies could eventually exist in the distant future to extend human lifespans beyond 1,000 years). Such interventions would be drastically different from previous improvements in human longevity, because they would introduce fundamental changes to how our bodies naturally work.

II: The Perils of Longevity

And yet, can doesn’t mean should. Few would object to the last century’s extensions in life expectancy or significant gains in healthspan, but hesitations creep in when the numbers grow well beyond previous natural limits.

Jorge Luis Borges, the brilliant author who gives this publication its name, penned a short story called “The Immortal,” in which a Roman soldier obtains immortality, realizes its horror, then toils for centuries in agony, searching for a mechanism to restore his finiteness. He finally returns to mortality, evidenced by a drop of blood pooling on his hand after scratching a thorny tree. “Incredulous, speechless, and in joy,” he celebrates the renewed prospect of death.

Perhaps the greatest fictional immortal being is Wowbagger the Infinitely Prolonged, from the Douglas Adams Hitchhiker’s Guide series. After being made immortal by “an unfortunate accident with an irrational particle accelerator, a liquid lunch and a pair of rubber bands,” Wowbagger eventually soured on life.

To begin with it was fun; he had a ball, living dangerously, taking risks, cleaning up on high-yield long-term investments, and just generally outliving the hell out of everybody.

In the end, it was the Sunday afternoons he couldn’t cope with, and that terrible listlessness that starts to set in at about 2:55, when you know you’ve taken all the baths you can usefully take that day, that however hard you stare at any given paragraph in the newspaper you will never actually read it, or use the revolutionary new pruning technique it describes, and that as you stare at the clock the hands will move relentlessly on to four o’clock, and you will enter the long dark teatime of the soul.

Wowbagger replaces drudgery with a fresh purpose: “He would insult the Universe. That is, he would insult everybody in it. Individually, personally, one by one, and (this was the thing he really decided to grit his teeth over) in alphabetical order.”

In a less playful final scene of the Czech play, The Makropulos Affair, characters are gathered together after seeing the damage inflicted by immortal suffering on the 342 year-old protagonist—who finds eternal existence tragic, boring, and cold. One by one, various characters are offered the chance to join her as an undying presence who never ages.³

Would you take a pill or drink an elixir if it promised a 200-year lifespan? How about 1,000? And, crucially, what would happen to society—to politics, to economics, to the structures that govern our lives—if we suddenly started living not just a bit longer, but twice as long as past generations?