If we are going to turn our population pyramid upside down in the next decades—and that’s what will happen, if it stands at all—then we are looking at a highly unstable situation, socially and politically. “A civilization has the same fragility as a life,” said Paul Valéry. Challenges to civil values, if they are too great, can lead to civil wars. What happens as the baby boomers go gray all over the world and have to be carried on the backs of their small number of adult children? The lengthening of our life span is the crowning achievement of our species, but the crown is heavy and the head that wears the crown is gray.
Global graying will be one of the great challenges of this century. Demographers will argue about the details for the rest of their lives and ours, just as climate scientists will argue about the details of global warming. But about the very broadest features, there are very few skeptics. We are living longer and staying healthy and vigorous later in life, and every man and woman on the street knows it. You can monitor global graying in your own hair. You can time it by the watch on your own wrist. Barring an apocalypse, the generations of humans alive today can expect to live longer (at least a little longer) than any generation before us.
No matter what else happens with the science of aging, more and more of us will follow it as global graying advances.
Since the problem of mortality will be so much on our minds, whatever our age, we will be watching this science from all sides. We’ll argue not only the feasibility of its goals but their desirability.
In France during the summer of 1783, Benjamin Franklin watched the brothers Montgolfier go aloft in a hot-air balloon. “It diminish’d in Apparent Magnitude as it rose,” he reported afterward in a letter to the Royal Society, “till it enter’d the Clouds, when it seemed to me scarce bigger than an Orange, and soon after became invisible, the Clouds concealing it.” A man in the crowd asked, “What’s the use of that?” And Franklin replied, “What is the use of a newborn baby?” He understood that the rise of modern science would mean life itself to us, and although he could not know how far or fast it would travel, he did foresee that the global enterprise would carry us toward ever longer and healthier lives. Later that same year, when the Montgolfiers staged a balloon demonstration before the French court and about 130,000 other onlookers, one Madame d’Houdetot had the same prophetic thought, and found it poignant. Madame d’Houdetot reflected, as she watched the balloon passing over Versailles, “Soon they shall discover how to live forever…and we shall be dead.”
Now, a generation or two after that New Yorker cartoon with the anxious reader of obituaries, we have Web comic strips like XKCD (“A Webcomic of Romance, Sarcasm, Math, and Language”). One strip shows a line of stick figures marching up a hill toward “The Uncomfortable Truths Well.” The figures suggest an endless, eternal line of pilgrims bearing questions, which the well answers one by one. And the first question? We know what it is, of course. Quoth the well: “Science may discover immortality, but it won’t happen in the next eighty years.”
Do we want the science to move faster? Do we want a cure for aging? The question of desirability is going to be hard for us. When we examine it closely our thoughts get tangled in it, much as we are entangled with mortality in our bodies. The spiritual and emotional knots are as tight as the biological. We’re mortals. We’ve wrestled with the problem of mortality for thousands of years in the darkest passages of Scripture and philosophy. Our poets and artists move us profoundly by struggles without answers. No other scientific program raises so many enormous and imponderable questions, and they are so blithely dismissed by the engineers who would build the dam in the valley of the shadow of death.
We can’t know yet if a cure for aging is almost within reach, if it is now low-hanging fruit. But when we turn from feasibility to desirability—when we let ourselves think about science and immortality in the same sentence, and take it seriously, even for a moment—we run into extraordinary turbulence as soon as our thoughts are aloft. Powerful currents run in us, alternating currents of yes and no. We meet internal resistances just as strong as in the body or the cell; and we only half understand them, even though we have been exploring the question “Should we?” for as long as the question “Could we?”
In Paradise Lost, Milton reminds us that we failed to make ourselves immortal when we reached for the low-hanging apple; in fact, we made things infinitely worse.
Of Man’s First Disobedience, and the Fruit
Of that Forbidden Tree, whose mortal taste
Brought Death into the World, and all our woe…
Milton reinforces the point of the lesson by making Satan fall and suffer at least as horribly as Adam and Eve. He does show some sneaking sympathy for the fallen angel, as Blake observes in a famous line in “The Marriage of Heaven and Hell”—“NOTE: The reason Milton wrote in fetters when he wrote of Angels & God, and at liberty when of Devils & Hell, is because he was a true Poet and of the Devil’s party without knowing it.” Even so, as Milton announces at the close of his grave and august first verse, the purpose of this epic, the point of “this great Argument,” is to “assert Eternal Providence, and justify the ways of God to men.”
All of Hebrew and Christian Scripture makes this assertion and insists that the ways of God are just; to be accepted with or without understanding; to be accepted even in the face of horror. Think of the ghastliest story in the book of Genesis, the testing of Abraham: in Jewish tradition, the episode of the Torah that is recited on the first day of the new year, again and again. Abraham and Sara have a child in their old age, a child so long prayed for and despaired of that when at last he is born they name him Isaac, which means “He laughs.” And God comes to Abraham and commands him to take his son, “your only-one, whom you love, Isaac,” up to the mountain and sacrifice him. So early in the morning Abraham saddles his donkey, takes Isaac, splits wood for the sacrifice, and with them goes up to the mountain. They climb the mountain, Isaac carrying the wood and Abraham the torch and the knife.
“Here’s the fire and the wood,” says Isaac, “but where is the sacrifice?”
And Abraham answers, “God will provide.”
When they come to the place, Abraham builds the pyre, binds Isaac on top of it, and stretches out the knife to slay his son—but God stops him. “Abraham lifted up his eyes and saw a ram caught in the thicket by its horns. And he offered up the ram in place of his son.”
Homer tells the same story of another patriarch, King Agamemnon. When Agamemnon wants to sail for Troy, the wind will not come up to fill the sails of the ships. A priest tells him that it is the will of the gods that he sacrifice his firstborn daughter, Iphigeneia. So Agamemnon dispatches a messenger to the girl’s mother, Clytemnestra, and tells her to send their daughter to him. He says Iphigeneia is to be married to his greatest warrior, Achilles. And the girl comes. In Homer, the king sacrifices his daughter; but in Euripides’s play Iphigeneia at Aulis, a goddess spirits the girl away at the very last moment and substitutes a deer, which Agamemnon kills instead.
It’s curious that this same tortured story should reappear at the core of several religions. In Christian tradition, the hill where Abraham bound Isaac and lifted the knife was Golgotha, also known as Calvary. That is the hill up which God sent his own son, carrying the wood of the cross on his back, to be sacrificed for the sake of all of humanity, as symbolized by the lamb of God.
Hindus know the story from the Upanishads. A father, Vajasravasa, pledges to sacrifice all that he has in return for the blessings of heaven. His young son Nachiketas watches as Vajasravasa’s cows are led away. “Dear father,” the son asks, “to whom wilt thou give me?”
His father is silent.
“Dear father,” he asks again, “to whom wilt thou give me?”
Silence.
“Dear father, to whom wilt thou give me?”
“I shall give thee unto Death!”
So the boy descends to the realms of Yama, who is Death. There he learns all the parado
xes of mortality and immortality, in some of the most celebrated poetry of Hindu scripture, which concludes, “When all the ties of the heart are severed here on earth, then the mortal becomes immortal—here ends the teaching.”
Framed this way, as the sacrifice of the child by the father, the story is even harder to accept than the sacrifice of the self. For anyone who has a father, or a child, it is infinitely more painful and bewildering to contemplate than the failure of Gilgamesh, or the fall of Adam and Eve. The very horror of the story forces us to reflect on the ultimate reason for this sacrifice. Whatever else they do, these stories push us to explore in the strongest possible form the struggle within us between acceptance and defiance, defiance and acceptance, in the flow of the generations. Every father does pass the problem of mortality to his child, because he must. Every child receives the problem of mortality from the father, because he must. And framed as it is, this recurring story makes life’s demands for acceptance and resistance impossible to decide for ourselves, impossible to resolve through reason, too much for mortal minds. This is the way it must be, the story says; we have to take it on faith.
The same story reappears in at least one more tradition: Lucretius retells the story of Agamemnon and Iphigeneia at the beginning of his epic poem The Way Things Are, a heroic effort to replace the epics of Homer and religious faith with the epic of what we now call science. In Book One, at line 101, we find the battle cry of the rationalists: Tantum religio potuit suadere malorum, “See what evils are done in the name of religion.” Lucretius’s furious line became a slogan of the Enlightenment and made him a favorite poet of the birth of science. The Loeb edition notes: “Voltaire, an ardent admirer of Lucretius, believed that line 101 would last as long as the world.”
Lucretius thought he could reason his way out of these terrors. Voltaire thought science could get us past them too. The modern age of the Enlightenment would dispel all darkness. But when we approach these questions now, through secular science, they are deep as ever. The problem of mortality does not go away when we look at it from a scientific point of view. The sacrifices are real and have always been real, our inheritances of loss, borne by each generation; and now we approach them from a new direction.
Some demographers predict, for instance, that we would want fewer children if we lived for hundreds or thousands of years. We see the trend already in the world’s developed countries; the longer we live, the smaller the families we choose. The trend might increase with our life expectancy. Those alive would stay alive. Those unborn would stay unborn. Galileo observed something like this centuries ago when he mocked the folly of people who think they can buy eternity in gems. He had nothing but contempt for the romantic idea that rubies and emeralds are pieces of immortality, that “diamonds are forever.” All of these dreams are ways of escaping for a moment from our mortal bodies, for getting off—in our imagination—from a mortal planet circling a mortal star. Fools, said Galileo, “are reduced to talking this way, I believe, by their great desire to go on living, and by the terror they have of death. They do not reflect that if men were immortal, they themselves would never have come into the world.”
Mortality is sacrifice. And the great argument of Scripture and Paradise Lost has its parallel now in a busy field of research, the study of the origins of aging at the level of single cells. A cell that reproduces by splitting in two will do better in the end if it divides unequally, with one half getting all the new parts, and the other half keeping some of the old parts. Cells began doing this very soon after the origin of life itself, more than three billion years ago.
According to present thinking, it all began with that first sacrifice. That was the moment when life invented aging. Those were the first cells doomed to age and die. From that moment on, mortality was ingrained within us.
Mortality is doubly ingrained in us, because it arose not once but twice. It was discovered first by those single cells, the authors of the first sacrifice, all those millions of years ago. And the invention of aging was so successful that life remained single-celled for two billion years—that is, for two-thirds of the time that there has been life on Earth. Even today, most of the life on the planet is still in the form of single cells.
Then, a billion years ago, for reasons that nobody understands, some of the single cells began to come together to form multicellular bodies. Some of the first colonies that formed were the ancestors of today’s sponges, which are very simple colonies. They are essentially immortal. Their aging is negligible. Other early colonies were the ancestors of today’s cnidarians, another large branch of the tree of life, which includes the hydra. The hydra lives in freshwater, but most cnidarians live in the sea, including sea anemones, corals, sea nettles, sea pens, and sea wasps—which are the world’s most poisonous animals; their sting can kill in less than three minutes. The cnidarians include jellyfish and the Portuguese man-of-war. They have nerves and muscles, and some of them have eyes. But most of these thousands of species hardly age. Like the sponges, they can regenerate from a tiny piece, sometimes even from a few scattered cells. When sponges and cnidarians grow new cells, they just slough off the old ones. Any wastes that have built up in those old cells are gone, and the new cells start afresh. So the cells in those animals age and die, but their bodies live on and on.
These immortalists evolved early; they were some of the first multicellular animals on the planet. And then mortal animals evolved. Why? What advantage did they get from becoming mortal?
A sponge has no nervous system. A hydra has networks of nerves but no brain. Both animals shed their nerves the way they shed the cells that make up their skin and their muscles, and then grow new ones. The forests of delicate synapses, which tie all our long-lived nerves together in the bundles we call the nervous system, were among the most important inventions in the history of life. They allowed animals to store more and more information. Long-lived neurons allowed them to maintain a historical memory, to learn from their experience and carry experience forward. The hydra loses its memories along with its old cells. Its memories go up in the flame and ash of the Phoenix. That is a price it pays for the gift of being born anew. Although the hydra lives much longer than its nerves, it sheds its experiences with them—whereas the nerves in a nervous system can last a lifetime, and with them, we have the memories of a lifetime.
Nerves are cells, and all cells accumulate wastes and damage. They age, but they are so specialized that they can no longer be replaced. The cells in the bone marrow proliferate as long as we live, as do the cells that line our guts. They divide and divide, and any junk that’s built up in them is diluted again and again so that they stay clean. In this way, the bone marrow and the linings of our guts and the cells of our liver can be said to be virtually immortal, like the hydra. But the highly specialized cells of our brains are mortal, and so are the cells of our hearts.
In essence, then, that was the second beginning of old age and mortality, in the evolution of these specialists. Ever since, animals with those kinds of long-lived but mortal cells have accumulated damage, and eventually they have failed. Because key parts of our bodies cannot last, we do not build the rest of our bodies to last. Ultimately, then, the cells that give us our identities are the ones that bring us down to the grave.
Terman and Brunk, the authors of the Garbage Catastrophe hypothesis, are among the gerontologists who have advanced this argument: that the need for the nerves brought death into the world a second time. They argue that our long-lived muscles may also have played a part in this second invention of mortality. What we call muscle memory emerges from a combination of the complex patterns we have laid down with our muscles and the firing of our nerves. It may be that the spectacularly complicated and graceful behavior of the more complex animals owes a great deal to their long-lived muscle fibers and long-lived nerves, lasting as long as the body itself.
This invention may have allowed the amazing diversification of life-forms that we call the Cambrian Explosion. I
f so, the invention of aging, the feature that ingrains our mortality in our flesh, made us such a success on the planet Earth.
The development of those long-lived cells would also have precluded reproduction by budding, which is the main way that hydra makes another hydra. It would have driven the evolution of the separation of bodies into the disposable soma and the protected germ cells, the sex cells. And so it would have furthered and spurred the evolution of aging. And it would have made possible something else, too. Animals with dangerous lives would have grown up fast and reproduced fast before they died. About half the animals on this planet are short-lived insects. But animals that found their way into protected niches could afford to slow down. Then they could benefit more and more from their long-lived muscles and memories. They could grow more and more intelligent. One animal line that did this more than any other was our own, the species Homo sapiens. We lost the gift of living more or less indefinitely, of aging negligibly. We lost the gift of living more or less negligently, without being aware of our losses. But we gained the gift of memory, of memories that can last all our lives.
We have what the hydra does not have. We have a sense of ourselves that goes back to our beginnings and looks ahead toward the infinitely various possibilities that surround our end. We exist, and we know we exist. But the price we pay is that we age, and that we know we age. The price we pay is that we know we are mortals.
And we must wrestle with these questions of acceptance or defiance.
Chapter 11
THE TROUBLE WITH IMMORTALITY
When we consider the problem of aging, and imagine that we might be able to cure it, that alternating current we feel consists of longings and dread. We are afraid of what we wish for; and most of our fears, like our hopes, have always cycled in us.
Long for This World Page 21