Suppose you had a chance to question an ancient Greek or Roman—or any of our distant ancestors, for that matter. Let’s say you asked them to list the qualities of a deity.

It’s a pretty good bet that many of the “god-like” traits he or she described might seem trivial nowadays.

After all, we think little of flying through the air. We fill pitch-dark areas with sudden lavish light, by exerting a mere twitch of a finger. Average folks routinely send messages or observe events taking place far across the globe. Copious and detailed information about the universe is readily available through crystal tubes many of us keep on our desks and command like genies. Some modern citizens can even hurl lightning, if we choose to annoy our neighbors and the electric company.

Few of us deem these powers to be miraculous, because they’ve been acquired by nearly everyone in prosperous nations. After all, nobody respects a gift if everybody has it. And yet, these are some of the very traits that earlier generations associated with divine beings.

Even so, we remain mortal.

Our obsession with that fate is as intense as it was in the time of Gilgamesh. Perhaps more, since we overcame so many other obstacles that thwarted our ancestors.

Will our descendants conquer the last barriers standing between humanity and Olympian glory? Or may we encounter hurdles too daunting even for our brilliant, arrogant, ingenious and ever-persevering species?

Human Lifespan

Here’s the safest prediction for the next 100 years—that mortality will be a major theme. Assuming we don’t blow up the world, or fall into some other catastrophic failure mode, human beings will inevitably focus on using advanced technology to cheat death.

Already the fruits of science and the Industrial Age give billions unprecedented hope of living out their full natural spans—one of the chief reasons that our planetary population has expanded so. While it’s true that these benefits still aren’t fairly or evenly distributed, an unprecedentedly large fraction of Earth’s inhabitants have grown up without any first-hand experience of plague or mass starvation. That rising percentage curve is more encouraging than the images you see on the 6 O’clock News, though it offers cold comfort to those still languishing in poverty.

Suppose, through a mix of compassion, creativity and good luck, we complete the difficult transition and manage to spread this happy situation to everyone across the globe, solving countless near-term crises along the way. Will future generations take a full life span as much for granted as modern Americans do?

Of course they will… and complain there’s nothing natural about an eighty- or ninety-year time limit on the adventure and enjoyment of life.

Many proposed methods of life-extension have come up for discussion:

Lifestyle adjustment

Intervention and Repair

Genetic Solutions

Waiting for better times

Transcendence

The first of these, lifestyle adjustment, would seem to offer surefire immediate rewards. After all, most of the increase in average lifespan we’ve seen in recent centuries came from nothing more complicated than proper diet and hygiene.

But that statistical boost is deceptive! It was achieved by increasing the fraction of babies who make it all the way to the borderlands of vigorous old age. This had little to do with pushing back the boundary itself; the realm that we call “elderly” still hovers somewhere near the biblical three score and ten.

Do all animal species have built-in expiration timers? Some fish and reptiles may not, but most creatures—and especially mammals—do seem to have an inner clock that triggers every individual’s decline to frailty after the middle years of fight-flight-and-reproduction run their course.

Mice and elephants lead very different lives—one slow and ponderous, the other manic and fleeting—yet rodents and pachyderms share the same pervasive pattern of aging. Individuals who survive the perils of daily life, from disease to predators, inevitably begin declining after they go through about half a billion heartbeats. (Elephants live much longer than mice, but their hearts also beat far slower, so the total allotment stays about the same.)

The same holds true across nearly all mammalian species. Few live to celebrate their billionth pulse. No one knows quite what this coincidence signifies. Moreover, the program isn’t quite rigid. In laboratories around the world, researchers have lately discovered exciting ways to slow the senescence timer—at least in mice and fruit flies—largely by keeping the test creatures hungry. By giving them nutritious but restricted diets, or by delaying sexual reproduction, researchers report in some cases doubling the usual lifespan.

As you might expect, quite a few human enthusiasts are now eagerly applying these lessons from the lab, limiting the calories they eat or forbearing sex, hoping to extend their own lifespans through judicious abstinence. Alas, the results achieved so far—such as a slight reduction in heart disease—have been disappointingly slim.

After a little reflection, this should come as no surprise. Across history, many civilizations have fostered ascetic movements, sometimes in large colonies where dedicated individuals lived spartan, abstemious lives. After four millennia of these experiments, wouldn’t we have noticed by now if swarms of spry, 200-year old monks were capering across the countryside?

There may be a good reason why simple life-style changes work in animals, but not us.

Remember that billion heartbeat limit that seems to confine all mammals, from shrews to giraffes? It’s a pretty neat correlation, until you ponder the chief exception.

Us.

Most mammals our size and weight are already fading away by age twenty or so, when humans are just hitting their stride. By eighty, we’ve had about three billion heartbeats! That’s quite a bonus.

How did we get so lucky?

Biologists figure that our evolving ancestors needed drastically extended lifespans, because humans came to rely on learning rather than instinct to create sophisticated, tool-using societies. That meant children needed a long time to develop. A mere two decades weren’t long enough for a man or woman to amass the knowledge needed for complex culture, let alone pass that wisdom on to new generations. (In fact, chimps and other apes share some of this lifespan bonus, getting about half as many extra heartbeats.)

So evolution rewarded those who found ways to slow the aging process. Almost any trick would have been enlisted, including all the chemical effects that researchers have recently stimulated in mice, through caloric restriction. In other words, we’ve probably already incorporated all the easy stuff! We’re the mammalian Methuselahs and little more will be achieved by asceticism or other drastic life-style adjustments. Good diet and exercise will help you get your eighty years. But to gain a whole lot more lifespan, we’re going to have to get technical.

So what about intervention and repair?

Are your organs failing? Grow new ones, using a culture of your own cells!

Are your arteries clogged? Send tiny nano-robots coursing through your bloodstream, scouring away plaque! Use tuned masers to break the excess intercell linkages that make flesh less flexible over time.

Install little chemical factories to synthesize and secrete the chemicals that your own glands no longer adequately produce. Brace brittle bones with ceramic coatings, stronger than the real thing!

In fact, we are already doing many of these things, in early-primitive versions. So there is no argument over whether such techniques will appear in coming decades, only how far they will take us.

Might enough breakthroughs coalesce at the same time to let us routinely offer everybody triple-digit spans of vigorous health? Or will these complicated interventions only add more digits to the cost of medical care, while struggling vainly against the same age-barrier in a frustrating war of diminishing returns?

I’m sure it will seem that way for the first few decades of the next century… until, perhaps, everything comes together in a rush. If that happens—if we suddenly find ourselves able to fix old age—there will surely be countless unforeseen consequences… and one outcome that’s absolutely predictable.

We’ll start taking that miracle for granted, too.

On the other hand, it may not work as planned. Many scientists suggest that attempts at intervention and repair will ultimately prove futile, because senescence and death are integral parts of our genetic nature. After all, from a purely biological point of view, we individuals are merely the grist of evolution, here to strive, compete and reproduce, if we can.

If our australopithecine ancestors had been ageless immortals, wouldn’t that have bollixed the cruelly creative process of natural selection that produced us? Biologists who believe in the intrinsic genetic clock say we should be grateful for those three billion heartbeats. After that, the best service we can do for our grandchildren is to get out of their way.

Other experts disagree. They think the “clock” is a mere coincidence, having to do with steadily accumulating errors in our cells. In particular, they point to telomeres—little chemical caps protecting the ends of our chromosomes—which wear away with time until the sheltering layer vanishes and grave erosion starts affecting the vulnerable DNA strands, instead. This gradual chemical deterioration simulates a destiny clock, though some researchers hope it might be halted, if we learn the right medical and biochemical tricks.

Whichever side is right about the nature and evolutionary origins of the aging clock, there are no obvious reasons why human beings can’t or won’t meddle with its programming, once we fully grasp how cell and genome work. Even if such tools come too late for today’s generation, intervention may help our descendants to live longer, healthier lives.

Long life may be just one of the benefits to spill from our rising pot of knowledge. Suppose we learn to emulate achievements of other Earthly species… say, hibernation. Might that bring us closer to another age-old dream, travel to the stars?

Hibernation, or suspended life, would also be a great way to travel forward through time. To see the future. Which brings up yet another way that some people think they can cheat death: by setting off on a one-way journey from our primitive era, hoping to emerge when civilization has solved many of the problems discussed here.

So far, our sole hope for such a voyage to the far-off future—is cryonics, the practice of freezing a terminal patient’s body, after he or she has been declared legally dead. Some of those who sign up for this service take the cheap route of having only their heads prepared and stored in liquid nitrogen, under the assumption that folks in the Thirtieth Century will simply grow fresh bodies on demand. Their logic is expressed with chilling rationality. “The real essence of who I am is the software contained in my brain. My old body—the hardware—is just meat.”

Polls show that a majority of citizens today perceive cryonics enthusiasts as kooky, perhaps even a bit grotesque with their Frankensteinian interest in dead bodies. In fact, I share some of this skepticism, though perhaps for different reasons.

Suppose future generations can grow new bodies on demand, and are able to transfer something like your original consciousness out of a frozen, damaged brain. It remains to be seen why they would want to.

Anyway, today’s cryo-storage process is messy, complex, legally shaky, and expensive. Wouldn’t any reasonable person—one worthy of revival—dedicate a lifetime’s accumulated resources to helping their children and posterity, instead of splurging it all on a chancy, self-important gamble for personal immortality?

And yet, cryonics devotees keep plugging away at their dream, refining their techniques, finding new ways to store brains with less damage and at lower cost—in much the same way that past generations of putterers strove to develop machines that could fly. The funny thing is that we may never know when they cross a threshold and finally do manage to freeze somebody well enough to be revived at a future time. All that’s certain is that the techno-zealots will go on trying. They see Death as a palpable enemy that can ultimately be defeated, like so many others we’ve overcome during our long ascent.

Is there some point at which cryonic storage would become so simple—so convenient and cheap—that you would shrug and say “sign me up”? Suppose it took a thousand-dollar annex to your insurance policy? A hundred dollars? Five bucks?

What would you do differently then, in your daily life, to help ensure that future generations will feel kindly toward you? Perhaps even kindly enough to want your primitive company. Would you additionally sponsor cryo-storage for half a dozen poor people? Or donate part of your fortune to endeavors that help make a better, richer (and therefore more generous) future world? Would you work hard to raise descendants worth bragging about? Or were you already planning to do most of those things, anyway?

Some people who sign up for storage believe their bank accounts alone—set up to earn dividends until some future era—will suffice to make them worthy of being thawed, repaired, and given full corporeal citizenship in a coming age of wonders.

Somehow, I wouldn’t give that bet anything like sure odds, no matter how many technological barriers future people overcome.

There is a final category of ways that people think they can cheat death. It falls under a single word—transcendence.

Throughout history, countless philosophers and devout believers have yearned to rise above the whole megillah of normal human existence—all the hungers, pangs, neuroses, fears, and limitations of brain and body—by transporting some internal essence—consciousness or the soul—to a plane of existence far greater and nobler than we perceive as mere ignorant Homo sapiens. This ever-present drive propelled a wide range of contradictory dogmas and creeds on all continents. But even amid such diversity there were certain common themes. All those hopes, yearnings and strivings focused on the spiritual—the notion that humans may achieve a higher state through prayer, moral behavior, or mental discipline.

In the last couple of centuries, however, a fourth track to the next plane has gained supporters—‘techno-transcendentalism.’ Under this variation, disciples hope to achieve an agreeable new level of existence by means of knowledge and skill. They feel we can transform human beings—and human nature—through the tools of technology and science.

Whether this attitude represents the worst sort of irreligious hubris, or should be viewed as a natural stage in our adolescent development, is ripe for extensive and wide-ranging discussion… at another time perhaps. For now though, let’s focus only on how it applies to human lifespan.

According to some techno-transcendentalists, “growing new bodies” will seem like child’s play in the future. Many of them eagerly predict a time, sooner than you think, when we’ll all plug into computer-mediated artificial worlds where the old animal-limitations will simply vanish. By “downloading” ourselves into vast simulated realms, we may become effectively immortal, breaking the tyrannical hold of mere fleshy cells and evolutionary “clocks.” In this way, deathlessness of the spirit might be achieved by technologically savvy, rather than moral merit.

If the boosters of this kind of transcendence are right, every other kind of “immortality” will prove obsolete. In fact, nearly all of our modern concerns will seem about as relevant as a Neolithic hunter roaming downtown Manhattan, worrying about finding enough flint nodules to chip into spear points.

Wise Enough to be Immortal?

All right, what if one of them finally works? All too often, we find that solving one problem only leads to others, sometimes even more vexing.

A number of eminent writers like Robert Heinlein, Greg Bear, Kim Stanley Robinson and Gregory Benford have speculated on possible consequences, should Mister G. Reaper ever be forced to hang up his scythe and seek other employment. For example, if the Death Barrier comes crashing down, will we be able to keep shoehorning new humans into a world already crowded with earlier generations? Or else, as envisioned by author John Varley, might such a breakthrough demand draconian population-control measures, limiting each person to one direct heir per lifespan?

What if overcoming death proves expensive? Shall we return to the ancient belief, common in some cultures, that immortality is reserved for the rich and mighty? Nancy Kress has written books that vividly foresee a time when the teeming poor resent rich immortals. In contrast, author Joe Haldeman suggested simple rules of social engineering that may help keep such a prize within reach by all.

More people could wind up dying by violence and accidents than old age. Might we then start to hunker down in our homes, preserving our long-but-frail lives by avoiding all risk? Or would ennui drive the long-lived to seek new thrills, like extreme sports, bringing death back out of retirement in order to add spice to an otherwise-dull eternity?

Such changes may already be underway as we enter an era some call the “Empire of the Old.” Each year, retirement hobbies drive ever-larger portions of the economy, foretelling vigor by an active elderly population—a wholesome trend portrayed in Bruce Sterling’s Holy Fire and my own The Transparent Society. On the down side, the power of older voters can terrorize politicians and warp allocation of resources. Sensible proposals to raise the retirement age by some fraction of the lifespan increase, are quashed by waves of irate and uncompromising self-interest. It’s a worrisome trend for any society to rank generous retirement supplements higher than good schools for its young. No such civilization can long endure.

What will happen when the elderly outnumber all others? This may soon appear less than far-fetched in countries like Japan, where restrictive immigration policies help ensure and accelerate the aging trend.

Even problems that seem far-off and speculative today may become critical when people live beyond a twelfth decade. For example, is there a limit to the number of memories that a human brain can store?

On a more fundamental level, are we about to insist, once again, that contemporary humanity is wise enough to overrule all of Nature’s checks and balances?

(The answer to that one is simple… of course we’ll insist! We always do.)

These are among the serious questions and quandaries we may face, perhaps sooner than you think. That is, I hope we face them, for they are the sort of predicaments generated by success.

But then, that’s how it always has been. If we leave our descendants a better world, they will take the good parts for granted and fume over consequences we never foresaw.

It is a pattern typical of adolescence, and one more clue that our adventure has barely begun.

[originally appeared in AOL’s Online Magazine iPlanet as part three of a series commissioned specifically to discuss the new Millennium.]