The search for immortality has an ancient pedigree. From the opulent courts of Chinese emperors to the austere cells of Indian sages, from the drafty northern European chambers of medieval alchemists to Ponce de Leon’s legendary — and probably falsely attributed — quest for the Fountain of Youth in the steaming jungles of the New World, the elixir of life has been sought for millennia.

Now, say some longevity experts, it may be within reach of scientists working in air-conditioned labs to unravel the genetic code, map the hidden processes of the immune system, explore nanotechnologies that could make possible repairs to body structures too tiny to see and to develop ways to grow or construct and then safely install new or synthetic body parts.

We don’t blink at new hip joints, transplanted heart valves or minuscule plastic lenses that unfold inside the eye like flowers following cataract surgery, longevity advocates argue, so what’s surprising about the looming possibility of even more extensive and complex replacements?

“We are now beginning to talk about curing old age. It really does look as though there is no fixed, non-changeable upper limit to life span,” Thomas von Zglinicki, professor of cellular gerontology at Newcastle University, told British newspaper The Independent in 2005. Newcastle recently established a cross-disciplinary research institute which fuses its biology and engineering faculties as part of an aggressive British program to “cure old age,” the newspaper’s Jane Feinmann reported.

Dr. Leonid Gavrilov, a Russian longevity researcher working at the University of Chicago, where he’s a director of the Centre of Aging, told The Independent that “replacing damaged organs to greatly extend the human lifespan by substituting young and healthy for old and failing is no longer science fiction.”

Gavrilov and his wife, Natalia Gavrilova, galvanized longevity research with their 1991 book, The Biology of Life Span: A Quantitative Approach, which is still cited as an authority by Encyclopedia Britannica.

The two scientists studied the mathematical models of reliability theory devised by engineers to assess systems failure in computers and other complex machines and then applied them to the human body, shedding light on why and how human beings age and then die.

MILLENNIAL LIFE SPAN

And in 2006, Dr. Aubrey de Grey, a theoretical biologist at Cambridge University, told the CBS program 60 Minutes that he thinks life spans on the order of 500 or even 1,000 years are possible.

Other scientists, of course, dismiss all this theorizing about intervening in genetic destiny to end or even reverse the aging process as the kind of speculation that drives science fiction.

Whatever it is, molecular biologists, genome mappers and nanoengineers working in high-tech 21st-century labs seem unimaginably distant from alchemists and necromancers and their faith in the Philosopher’s Stone or their belief that an elixir to indefinitely extend human life might be distilled from mercury.

Science fiction writers are another matter. They have long speculated on the possibilities and perils of both extended and eternal life, in some cases with uncanny foresight that anticipates today’s emerging debates over science and ethics.

Longevity has been a persistent motif in speculative literature from the 19th century into the 21st.

Oscar Wilde wrote in the 1890s about a painting that ages while its subject experiences eternal youth. In a mid-20th-century novel by Richard Meredith, armies of slain soldiers are revivified and returned to battle. And contemporary novelist C.J. Cherryh provides gripping accounts of states that clone their citizens and of the power struggle that ensues on an interstellar spaceship when a powerful captain’s rejuvenation treatments begin to fail. Some sci-fi portrays artificially extended longevity as leading to repressive, totalitarian societies characterized by class repression.

In them, immortals emerge as a wealthy, privileged elite that rules over an underclass condemned to normal life spans. The 1997 movie Gattaca expresses disquiet at the possibility of a new kind of caste system with the genetically enhanced discriminating against the genetically un-enhanced.

Others portray future longevity as permitting humanity to ultimately leave the solar system and Star Trek through a universe of biotech wonders in which replacement organs can be artificially grown and the genetic code can be rewritten to eliminate old age entirely — and disease, too, for that matter.

Yet, some envisage only a dystopian nightmare of black-market body parts, the brutal organ-leggers who provide them and slave-like clones genetically modified to perform only their assigned tasks.

Still others postulate a world in which the next evolutionary step merges human beings with self-replicating, self-repairing machines — think The Matrix — culminating in the achievement of immortality through the uploading of human consciousness to computer systems or the creation of artificial intelligences which replicate human minds.

Science fiction aficionados have always argued that whatever humans can imagine lies within the realm of possibility — unlikely and far-fetched, perhaps, yet nonetheless possible. It’s a strong argument considering the impossibilities of the past that become the commonplace of the present and which will certainly be the humdrum obsolescence of the future.

Icarus has been to the moon and has his sights on Mars; Captain Nemo commands a Trident submarine capable of obliterating continents; Captain Kirk’s cheesy TV signalling device morphs into the smart phone; Democritus theorized invisible atoms almost 2,300 years before science confirmed their existence. It was an age illuminated only by fire. Now his descendants harness the atom for electricity that illuminates cities with suburbs more populous than all of Classical Greece.

So maybe it’s not surprising that what was once the domain of alchemists, fabulists and novelists now slips into everyday scientific discourse and even begins to populate the worries of actuaries and pension managers fretting over clients who are outliving their funds.

Today’s social planners must cope with the emerging prospect of too many elderly in retirement — and too few in the workforce to support them and their expensive health-care needs.

And philosophers and theologians wrestle with the ethics and morality of longevity.

In Canada, according to reports for Canwest News Service, census data show those 80 and older — already more than a million strong — now make up the second-fastest-growing age cohort in the country. The number of Canadians aged 100-plus has increased by more than 50 per cent since 1998 and could triple again by 2031.

ETHICAL PROBLEMS

What’s our current dialogue over mandatory retirement, the adequacy of pension fund capitalization and the usefulness of the retired and the semi-retired to the labour pool if not a public discussion about the ethical problems posed by longevity? The discussion itself is an acknowledgement that youthfulness and health are already being extended beyond ages once stereotyped as frail and decrepit.

Quite reasonably, fears arise that increasing numbers of people living into very old age will be accompanied by a rising tide of dementia. The Alzheimer Society of Canada recently ran projections that suggest the number of Canadians living with the disease could double over the next 25 years.

Some estimates project that while today there are fewer than half a million centenarians worldwide, by mid-century there will be almost a million people aged 100 or more in the U.S. alone. Canada is expected to have more than 14,000 such citizens by 2031.

In fact, centenarians, once worthy of special notice from the Queen (in fairness, they still get an official birthday greeting from Buckingham Palace) are the fastest-growing group of seniors in the developed world. But the 100th birthday club has already had its exotic place usurped by the super-centenarians — people living beyond 110 years, of whom more than 90 are now registered on the website of the U.S.-based Gerontology Research Group.

Right now, the upper range for human life appears to be 122, the verified age of Jean Calment of France when he died in 1997. However, news reports claim the pension book of India’s Habib Miyan shows his birth date as May 20, 1879, which would have made him 129 when he died in 2008. An Israeli woman, Mariam Amash, claimed as-yet-unverified birth documents issued by the long-defunct Ottoman Empire in 1888 showed her to be over 120.

There have been claims of longer life spans in antiquity. The Encyclopedia Britannica cites several ranging from 140 to 169 years but notes that on closer analysis none could be verified and all are deeply suspect.

Nonetheless, the population of super-centenarians is growing and statistically, the more people there are who reach 110 or 115, the more likely there will be those who survive even longer.

At such ages, of course, claims to be the world’s oldest human are ephemeral, so it’s risky for columnists to attribute the honour to any individual with any certainty.

However, given the growing numbers of the very old, the extension of good health far into that old age and dramatic increases in life expectancy over the past century, the notion that the first 150-year-old may already be among us seems eminently plausible.

Even without scientific breakthroughs in longevity, the basic math clearly indicates that’s where the life span trajectory is headed.

Life expectancy at birth in the time of Augustus Caesar was between 22 and 25 years, according to the guesstimates of demographers. Vital statistics weren’t kept by the state then, so there’s not much hard data to work with.

We do know that life expectancy in the ancient world was negatively influenced by poor understanding of the transmission mechanisms for communicable diseases, by poor hygiene and by food insecurity that touched all but the rich and powerful, while famine, war and pestilence were commonplace.

Yet by 1850, life expectancy had almost doubled. Extraordinarily dramatic spikes can be charted alongside a series of Victorian technological revolutions that led to improved health, incomes, nutrition and food security.

PUBLIC RESPONSIBILITIES

Vaccination, antisepsis and complicated surgical interventions made possible only by anesthetics were then amplified by awareness that health, sanitation and food safety were public rather than private responsibilities.

Women’s life expectancy in developed nations surged dramatically when the germ theory of disease and the use of antiseptics sharply reduced childbirth infections after 1870.

Between 1880 and 1900, life expectancy in the developed nations jumped by six years. Between 1900 and 1920, with the advent of blood transfusions, X-rays, immunizations for cholera and other diseases and better food preservatives, it jumped by another 7.4 years.

Between 1920 and 1940, with the discovery of insulin, vaccines for tuberculosis, tetanus, typhus and yellow fever and the first broad-spectrum antibiotic, penicillin, life expectancy again increased by 7.4 years.

Over the past century and a half, life spans have averaged an increase of just over 2.5 years every decade. If those scientists who say there appears to be no upper limit on age are correct, if trends in increasing life expectancy are sustained or accelerated by medical breakthroughs, then it certainly seems plausible to speculate that somebody alive today might indeed still be living in 2159.