The long habit of living indisposeth us for dying.

Sir THOMAS BROWNE

CELL REPAIR MACHINES raise questions involving the value of extending human life. These are not the questions of today's medical ethics, which commonly involve dilemmas posed by scarce, costly, and half-effective treatments. They are instead questions involving the value of long, healthy lives achieved by inexpensive means.

 For people who value human life and enjoy living, such questions may need no answer. But after a decade marked by concern about population growth, pollution, and resource depletion, many people may question the desirability of extending life; such concerns have fostered the spread of pro-death memes. These memes must be examined afresh, because many have roots in an obsolete worldview. Nanotechnology will change far more than just human lifespan.

 We will gain the means not only to heal ourselves, but to heal Earth of the wounds we have inflicted. Since saving lives will increase the number of the living, life extension raises questions about the effect of more people. Our ability to heal the Earth will lessen one cause for controversy.  

Still, cell repair machines themselves will surely stir controversy. They disturb traditional assumptions about our bodies and our futures: this makes doubt soothing. They will require several major breakthroughs: this makes doubt easy. Since the possibility or impossibility of cell repair machines raises important issues, it makes sense to consider what objections might be raised.

Why Not Cell Repair Machines?

What sort of argument could suggest that cell repair machines are impossible? A successful argument must manage some strange contortions. It must somehow hold that molecular machines cannot build and repair cells, while granting that the molecular machines in our bodies actually do build and repair cells every day. A cruel problem for the committed skeptic! True, artificial machines must do what natural machines fail to do, but they need not do anything qualitatively novel. Both natural and artificial repair devices must reach, identify, and rebuild molecular structures. We will be able to improve on existing DNA repair enzymes simply by comparing several DNA strands at once, so nature obviously hasn't found all the tricks. Since this example explodes any general argument that repair machines cannot improve on nature, a good case against cell repair machines seems difficult to make.  

Still, two general questions deserve direct answers. First, why should we expect to achieve long life in the coming decades, when people have tried and failed for millennia? Second, if we can indeed use cell repair machines to extend lives, then why hasn't nature (which has been repairing cells for billions of years) already perfected them?

 People have tried and failed.

 For centuries, people have longed to escape their short life spans. Every so often, a Ponce de Leon or a quack doctor has promised a potion, but it has never worked. These statistics of failure have persuaded some people that, since all attempts have failed, all always will fail. They say "Aging is natural," and to them that seems reason enough. Medical advances may have shaken their views, but advances have chiefly reduced early death, not extended maximum life-span.

 But now biochemists have gone to work examining the machines that build, repair, and control cells. They have learned to assemble viruses and reprogram bacteria. For the first time in history, people are examining their molecules and unraveling the molecular secrets of life. It seems that molecular engineers will eventually combine improved biochemical knowledge with improved molecular machines, learning to repair damaged tissue structures and so rejuvenate them. This is nothing strange - it would be strange, rather, if such powerful knowledge and abilities did not bring dramatic results. The massive statistics of past failure are simply irrelevant, because we have never before tried to build cell repair machines.

 Nature has tried and failed.

 Nature has been building cell repair machines. Evolution has tinkered with multicelled animals for hundreds of millions of years, yet advanced animals all age and die, because nature's nanomachines repair cells imperfectly. Why should improvements be possible?

 Rats mature in months, and then age and die in about two years - yet human beings have evolved to live over thirty times longer. If longer lives were the chief goal of evolution, then rats would live longer too. But durability has costs: to repair cells requires an investment in energy, materials, and repair machines. Rat genes direct rat bodies to invest in swift growth and reproduction, not in meticulous self-repair. A rat that dallied in reaching breeding size would run a greater risk of becoming a cat snack first. Rat genes have prospered by treating rat bodies as cheap throwaways. Human genes likewise discard human beings, though after a life a few dozen times longer than a rat's.

 But shoddy repairs are not the only cause of aging. Genes turn egg cells into adults through a pattern of development which rolls forward at fairly steady speed. This pattern is fairly consistent because evolution seldom changes a basic design. Just as the basic pattern of the DNA-RNA-protein system froze several billions of years ago, so the basic pattern of chemical signals and tissue responses that guides mammalian development jelled many millions of years ago. That process apparently has a clock, set to run at different speeds in different species, and a program that runs out.

 Whatever the causes of aging, evolution has had little reason to eliminate them. If genes built individuals able to stay healthy for millennia, they would gain little advantage in their "effort" to replicate. Most individuals would still die young from starvation, predation, accident, or disease. As Sir Peter Medawar points out, a gene that helps the young (who are many) but harms the old (who are few) will replicate well and so spread through the population. If enough such genes accumulate, animals become programmed to die.  

Experiments by Dr. Leonard Hayflick suggest that cells contain "clocks" that count cell divisions and stop the division process when the count gets too high. A mechanism of this sort can help young animals: if cancer-like changes make a cell divide too rapidly, but fail to destroy its clock, then it will grow to a tumor of limited size. The clock would thus prevent the unlimited growth of a true cancer. Such clocks could harm older animals by stopping the division of normal cells, ending tissue renewal, The animal thus would benefit from reduced cancer rates when young, yet have cause to complain if it lives to grow old. But its genes won't listen - they will have jumped ship earlier, as copies passed to the next generation. With cell repair machines we will be able to reset such clocks. Nothing suggests that evolution has perfected our bodies even by the brute standard of survival and reproduction. Engineers don't wire computers with slow, nerve-like fibers or build machines out of soft protein, and for good reason. Genetic evolution (unlike memetic evolution) has been unable to leap to new materials or new systems, but has instead refined and extended the old ones.  

The cell's repair machines fall far short of the limits of the possible - they don't even have computers to direct them. The lack of nano-computers in cells, of course, shows only that computers couldn't (or simply didn't) evolve gradually from other molecular machines. Nature has failed to build the best possible cell repair machines, but there have been ample reasons.

Healing And Protecting The Earth

The failure of Earth's biological systems to adapt to the industrial revolution is also easy to understand. From deforestation to dioxin, we have caused damage faster than evolution can respond. As we have sought more food, goods, and services, our use of bulk technology has forced us to continue such damage. With future technology, though, we will be able to do more good for ourselves, yet do less harm to the Earth. In addition, we will be able to build planet-mending machines to correct damage already done. Cells are not all we will want to repair.

 Consider the toxic waste problem. Whether in our air, soil, or water, wastes concern us because they can harm living systems. But any materials that come in contact with the molecular machinery of life can themselves be reached by other forms of molecular machinery. This means that we will be able to design cleaning machines to remove these poisons wherever they could harm life.

 Some wastes, such as dioxin, consist of dangerous molecules made of innocuous atoms. Cleaning machines will render them harmless by rearranging their atoms. Other wastes, such as lead and radioactive isotopes, contain dangerous atoms. Cleaning machines will collect these for disposal in any one of several ways. Lead comes from Earth's rocks; assemblers could build it into rocks in the mines from which it came. Radioactive isotopes could also be isolated from living things, either by building them into stable rock or by more drastic means. Using cheap, reliable space transportation systems, we could bury them in the dead, dry rock of the Moon. Using nanomachines, we could seal them in self-repairing, self-sealing containers the size of hills and powered by desert sunlight. These would be more secure than any passive rock or cask.

 With replicating assemblers, we will even be able to remove the billions of tons of carbon dioxide that our fuel-burning civilization has dumped into the atmosphere. Climatologists project that climbing carbon dioxide levels, by trapping solar energy, will partially melt the polar caps, raising sea levels and flooding coasts sometime in the middle of the next century. Replicating assemblers, though, will make solar power cheap enough to eliminate the need for fossil fuels. Like trees, solar-powered nanomachines will be able to extract carbon dioxide from the air and split off the oxygen. Unlike trees, they will be able to grow deep storage roots and place carbon back in the coal seams and oil fields from which it came.

 Future planet-healing machines will also help us mend torn landscapes and restore damaged ecosystems. Mining has scraped and pitted the Earth; carelessness has littered it. Fighting forest fires has let undergrowth thrive, replacing the cathedral-like openness of ancient forests with scrub growth that feeds more dangerous fires. We will use inexpensive, sophisticated robots to reverse these effects and others. Able to move rock and soil, they will re-contour torn lands. Able to weed and digest, they will simulate the clearing effects of natural forest fires without danger or devastation. Able to lift and move trees, they will thin thick stands and reforest bare hills. We will make squirrel-sized devices with a taste for old trash. We will make treelike devices with roots that spread deep and cleanse the soil of pesticides and excess acid. We will make insect-sized lichen cleaners and spray-paint nibblers. We will make whatever devices we need to clean up the mess left by twentieth-century civilization.

 After the cleanup, we will recycle most of these machines, keeping only those we still need to protect the environment from a cleaner civilization based on molecular technology. These more lasting devices will supplement natural ecosystems wherever needed, to balance and heal the effects of humanity. To make them effective, harmless, and hidden will be a craft requiring not just automated engineering, but knowledge of nature and a sense of art.

 With cell repair technology, we will even be able to return some species from apparent extinction. The African quagga - a zebra-like animal - became extinct over a century ago, but a salt-preserved quagga pelt survived in a German museum. Alan Wilson of the University of California at Berkeley and his co-workers have used enzymes to extract DNA fragments from muscle tissue attached to this pelt. They cloned the fragments in bacteria, compared them to zebra DNA, and found (as expected) that the genes showed a close evolutionary relationship. They have also succeeded in extracting and replicating DNA from a century-old bison pelt and from millennia-old mammoths preserved in the arctic permafrost. This success is a far cry from cloning a whole cell or organism - cloning one gene leaves about 100,000 uncloned, and cloning every gene still doesn't repair a single cell - but it does show that the hereditary material of these species still survives.

 As I described in the last chapter, machines that compare several damaged copies of a DNA molecule will be able to reconstruct an undamaged original - and the billions of cells in a dried skin contain billions of copies. From these, we will be able to reconstruct undamaged DNA, and around the DNA we will be able to construct undamaged cells of whatever type we desire. Some insect species pass through winter as egg cells, to be revived by the warmth of spring. These "extinct" species will pass through the twentieth century as skin and muscle cells, to be converted into fertile eggs and revived by cell repair machines.

 Dr. Barbara Durrant, a reproductive physiologist at the San Diego Zoo, is preserving tissue samples from endangered species in a cryogenic freezer. The payoff may be greater than most people now expect. Preserving just tissue samples doesn't preserve the life of an animal or an ecosystem, but it does preserve the genetic heritage of the sampled species. We would be reckless if we failed to take out this insurance policy against the permanent loss of species. The prospect of cell repair machines thus affects our choices today.

 Extinction is not a new problem. About 65 million years ago, most then-existing species vanished, including all species of dinosaur. In Earth's book of stone, the story of the dinosaurs ends on a page consisting of a thin layer of clay. The clay is rich in iridium, an element common in asteroids and comets. The best current theory indicates that a blast from the sky smashed Earth's biosphere. With the energy of a hundred million megatons of TNT, it spread dust and an "asteroidal winter" planet-wide.  

In the eons since living cells first banded together to form worms, Earth has suffered five great extinctions. Only 34 million years ago - some 30 million years after the dinosaurs died - a layer of glassy beads settled to the sea floor. Above that layer the fossils of many species vanish. These beads froze from the molten splash of an impact.  

Meteor Crater, in Arizona, bears witness to a smaller, more recent blast equaling that of a four-megaton bomb. As recently as June 30, 1908, a ball of fire split the Siberian sky and blasted the forest flat across an area a hundred kilometers wide.  

As people have long suspected, the dinosaurs died because they were stupid. Not that they were too stupid to feed, walk, or guard their eggs - they did survive for 140 million years - they were merely too stupid to build telescopes able to detect asteroids and spacecraft able to deflect them from collision with Earth. Space has more rocks to throw at us, but we are showing signs of adequate intelligence to deal with them. When nanotechnology and automated engineering give us a more capable space technology, we will find it easy to track and deflect asteroids; in fact, we could do it with technology available today. We can both heal Earth and protect it.

Long Life and Population Pressure

People commonly seek long, healthy lives, yet the prospect of a dramatic success is unsettling. Might greater longevity harm the quality of life? How will the prospect of long life affect our immediate problems? Though most effects cannot be foreseen, some can.

 For example, as cell repair machines extend life, they will increase population. If all else were equal, more people would mean greater crowding, pollution, and scarcity - but all else will not be equal: the very advances in automated engineering and nanotechnology that will bring cell repair machines will also help us heal the Earth, protect it, and live more lightly upon it. We will be able to produce our necessities and luxuries without polluting our air, land, or water. We will be able to get resources and make things without scarring the landscape with mines or cluttering it with factories. With efficient assemblers making durable products, we will produce things of greater value with less waste. More people will be able to live on Earth, yet do less harm to it - or to one another, if we somehow manage to use our new abilities for good ends.

 If one were to see the night sky as a black wall and expect the technology race to screech to a polite halt, then it would be natural to fear that long-lived people would be a burden on the "poor, crowded world of our children." This fear stems from the illusion that life is a zero-sum game, that having more people always means slicing a small pie thinner. But when we become able to repair cells, we will also be able to build replicating assemblers and excellent spacecraft. Our "poor" descendants will share a world the size of the solar system, with matter, energy, and potential living space dwarfing our entire planet.

 This will open room enough for an era of growth and prosperity far beyond any precedent. Yet the solar system itself is finite, and the stars are distant. On Earth, even the cleanest assembler-based industries will produce waste heat. Concern about population and resources will remain important because the exponential growth of replicators (such as people) can eventually overrun any finite resource base.

 But does this mean that we should sacrifice lives to delay the crunch? A few people may volunteer themselves, but they will do little good. In truth, life extension will have little effect on the basic problem: exponential growth will remain exponential whether people die young or live indefinitely. A martyr, by dying early, could delay the crisis by a fraction of a second - but a halfway dedicated person could help more by joining a movement of long-lived people working to solve this long-range problem. After all, many people have ignored the limits to growth on Earth. Who but the long-lived will prepare for the firmer but more distant limits to growth in the world beyond Earth? Those concerned with long-term limits will serve humanity best by staying alive, to keep their concern alive.

 Long life also raises the threat of cultural stagnation. If this were an inevitable problem of long life, it is unclear what one could do about it - machine-gun the old for holding firm opinions, perhaps? Fortunately, two factors will reduce the problem somewhat. First, in a world with an open frontier the young will be able to move out, build new worlds, test new ideas, and then either persuade their elders to change or leave them behind. Second, people old in years will be young in body and brain. Aging slows both learning and thought, as it slows other physical processes; rejuvenation will speed them again. Since youthful muscles and sinews make young bodies more flexible, perhaps youthful brain tissues will keep minds somewhat more flexible, even when steeped in long years of wisdom.

The Effects of Anticipation

Long life will not be the greatest of the future's problems. It might even help solve them.  

Consider its effect on people's willingness to start wars. Aging and death have made slaughter in combat more acceptable: As Homer had Sarpedon, hero of Troy, say, "O my friend, if we, leaving this war, could escape from age and death, I should not here be fighting in the van; but now, since many are the modes of death impending over us which no man can hope to shun, let us press on and give renown to other men, or win it for ourselves."  

Yet if the hope of escaping age and death turns people from battle, will this be good? It might discourage small wars that could grow into a nuclear holocaust. But equally, it might weaken our resolve to defend ourselves from lifelong oppression - if we take no account of how much more life we have to defend. The reluctance of others to die for their ruler's power will help.

 Expectations always shape actions. Our institutions and personal plans both reflect our expectation that all adults now living will die in mere decades. Consider how this belief inflames the urge to acquire, to ignore the future in pursuit of a fleeting pleasure. Consider how it blinds us to the future, and obscures the long-term benefits of cooperation. Erich Fromm writes: "If the individual lived five hundred or one thousand years, this clash (between his interests and those of society) might not exist or at least might be considerably reduced. He then might live and harvest with joy what he sowed in sorrow; the suffering of one historical period which will bear fruit in the next one could bear fruit for him too." Whether or not most people will still live for the present is beside the point: the question is, might there be a significant change for the better?

 The expectation of living a long life in a better future may well make some political diseases less deadly. Human conflicts are far too deep and strong to be uprooted by any simple change, yet the prospect of vast wealth tomorrow may at least lessen the urge to fight over crumbs today. The problem of conflict is great, and we need all the help we can get.  

The prospect of personal deterioration and death has always made thoughts of the future less pleasant. Visions of pollution, poverty, and nuclear annihilation have recently made thoughts of the future almost too gruesome to bear. Yet with at least a hope of a better future and time to enjoy it, we may look forward more willingly. Looking forward, we will see more. Having a personal stake, we will care more. Greater hope and foresight will benefit both the present and posterity; they will even better our odds of survival.  

Lengthened lives will mean more people, but without greatly worsening tomorrow's population problem. The expectation of longer lives in a better world will bring real benefits, by encouraging people to give more thought to the future. Overall, long life and its anticipation seem good for society, just as shortening life spans to thirty would be bad. Many people want long, healthy lives for themselves. What are the prospects for the present generation?

Progress in Life Extension

Hear Gilgamesh, King of Uruk:

"I have looked over the wall and I see the bodies floating on the river, and that will be my lot also. Indeed I know it is so, for whoever is tallest among men cannot reach the heavens, and the greatest cannot encompass the earth."

Four millennia have passed since Sumerian scribes marked clay tablets to record The Epic of Gilgamesh, and times have changed. Men no taller than average have now reached the heavens and circled the Earth. We of the Space Age, the Biotechnology Age, the Age of Breakthroughs - need we still despair before the barrier of years? Or will we learn the art of life extension soon enough to save ourselves and those we love from dissolution?

 The pace of biomedical advance holds tantalizing promise. The major diseases of age - heart disease, stroke, and cancer - have begun to yield to treatment. Studies of aging mechanisms have begun to bear fruit, and researchers have extended animals' life spans. As knowledge builds on knowledge and tools lead to new tools, advances seem sure to accelerate. Even without cell repair machines, we have reason to expect major progress toward slowing and partially reversing aging.

 Although people of all ages will benefit from these advances, the young will benefit more. Those surviving long enough will reach a time when aging becomes fully reversible: at the latest, the time of advanced cell repair machines. Then, if not sooner, people will grow healthier as they grow older, improving like wine instead of spoiling like milk. They will, if they choose, regain excellent health and live a long, long time.

 In that time, with its replicators and cheap spaceflight, people will have both long lives and room and resources enough to enjoy them. A question that may roll bitterly off the tongue is: "When?... Which will be the last generation to age and die, and which the first to win through?" Many people now share the quiet expectation that aging will someday be conquered. But are those now alive doomed by a fluke of premature birth? The answer will prove both clear and startling.  

The obvious path to long life involves living long enough to be rejuvenated by cell repair machines. Advances in biochemistry and molecular technology will extend life, and in the time won they will extend it yet more. At first we will use drugs, diet, and exercise to extend healthy life. Within several decades, advances in nanotechnology will likely bring early cell repair machines - and with the aid of automated engineering, early machines may promptly be followed by advanced machines. Dates must remain mere guesses, but a guess will serve better than a simple question mark.

 Imagine someone who is now thirty years old. In another thirty years, biotechnology will have advanced greatly, yet that thirty-year-old will be only sixty. Statistical tables which assume no advances in medicine say that a thirty-year-old U.S. citizen can now expect to live almost fifty more years - that is, well into the 2030s. Fairly routine advances (of sorts demonstrated in animals) seem likely to add years, perhaps decades, to life by 2030. The mere beginnings of cell repair technology might extend life by several decades. In short, the medicine of 2010, 2020, and 2030 seems likely to extend our thirty-year-old's life into the 2040s and 2050s. By then, if not before, medical advances may permit actual rejuvenation. Thus, those under thirty (and perhaps those substantially older) can look forward - at least tentatively - to medicine's overtaking their aging process and delivering them safely to an era of cell repair, vigor, and indefinite life-span.  

If this were the whole story, then the division between the last on the road to early death and the first on the road to long life would be perhaps the ultimate gap between generations. What is more, a gnawing uncertainty about one's own fate would give reason to push the whole matter into the subconscious dungeon of disturbing speculations.

 But is this really our situation? There seems to be another way to save lives, one based on cell repair machines, yet applicable today. As the last chapter described, repair machines will be able to heal tissue so long as its essential structure is preserved. A tissues ability to metabolize and to repair itself becomes unimportant; the discussion of biostasis illustrated this. Biostasis, as described, will use molecular devices to stop function and preserve structure by cross-linking the cell's molecular machines to one another. Nanomachines will reverse biostasis by repairing molecular damage, removing cross-links, and helping cells (and hence tissues, organs, and the whole body) return to normal function.

 Reaching an era with advanced cell repair machines seems the key to long life and health, because almost all physical problems will then be curable. One might manage to arrive in that era by remaining alive and active through all the years between now and then - but this is merely the most obvious way, the way that requires a minimum of foresight. Patients today often suffer a collapse of heart function while the brain structures that embody memory and personality remain intact. In such cases, might not today's medical technology be able to stop biological processes in a way that tomorrow's medical technology will be able to reverse? If so, then most deaths are now prematurely diagnosed, and needless.

   [Post New Comment]
   Mind·X Discussion About This Article:

		Life Span posted on 07/17/2002 8:04 PM by dermerzel@hotmail.com	[Top] [Mind·X] [Reply to this post]
	Ok, where and how soon can I sign up???