Engines of Creation
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Source:
Foresight.org
Engines of Healing - Chapter 7
Life, Mind, and Machines
References for Chapter
7:
One of the things which distinguishes ours from all earlier
generations is this, that we have seen our atoms.
WE WILL USE molecular technology to bring health because the human
body is made of molecules. The ill, the old, and the injured all suffer from
mis-arranged patterns of atoms, whether mis-arranged by invading viruses,
passing time, or swerving cars. Devices able to rearrange atoms will be able to
set them right. Nanotechnology will bring a fundamental breakthrough in
medicine.
Physicians now rely chiefly on surgery and drugs to treat illness.
Surgeons have advanced from stitching wounds and amputating limbs to repairing
hearts and re-attaching limbs. Using microscopes and fine tools, they join
delicate blood vessels and nerves. Yet even the best micro-surgeon cannot cut
and stitch finer tissue structures. Modern scalpels and sutures are simply too
coarse for repairing capillaries, cells, and molecules. Consider "delicate"
surgery from a cell's perspective: a huge blade sweeps down, chopping blindly
past and through the molecular machinery of a crowd of cells, slaughtering
thousands. Later, a great obelisk plunges through the divided crowd, dragging a
cable as wide as a freight train behind it to rope the crowd together again.
From a cell's perspective, even the most delicate surgery, performed with
exquisite knives and great skill, is still a butcher job. Only the ability of
cells to abandon their dead, regroup, and multiply makes healing possible.
Yet as many paralyzed accident victims know too well, not all
tissues heal.
Drug therapy, unlike surgery, deals with the finest structures in
cells. Drug molecules are simple molecular devices. Many affect specific
molecules in cells. Morphine molecules, for example, bind to certain receptor
molecules in brain cells, affecting the neural impulses that signal pain.
Insulin, beta blockers, and other drugs fit other receptors. But drug molecules
work without direction. Once dumped into the body, they tumble and bump around
in solution haphazardly until they bump a target molecule, fit, and stick,
affecting its function.
Surgeons can see problems and plan actions, but they wield crude
tools; drug molecules affect tissues at the molecular level, but they are too
simple to sense, plan, and act. But molecular machines directed by nanocomputers
will offer physicians another choice. They will combine sensors, programs, and
molecular tools to form systems able to examine and repair the ultimate
components of individual cells. They will bring surgical control to the
molecular domain.
These advanced molecular devices will be years in arriving, but
researchers motivated by medical needs are already studying molecular machines
and molecular engineering. The best drugs affect specific molecular machines in
specific ways. Penicillin, for example, kills certain bacteria by jamming the
nanomachinery they use to build their cell walls, yet it has little effect on
human cells.
Biochemists study molecular machines both to learn how to build
them and to learn how to wreck them. Around the world (and especially the Third
World) a disgusting variety of viruses, bacteria, protozoa, fungi, and worms
parasitize human flesh. Like penicillin, safe, effective drugs for these
diseases would jam the parasite's molecular machinery while leaving human
molecular machinery unharmed. Dr. Seymour Cohen, professor of pharmacological
science at SUNY (Stony Brook, New York), argues that biochemists should
systematically study the molecular machinery of these parasites. Once
biochemists have determined the shape and function of a vital protein machine,
they then could often design a molecule shaped to jam it and ruin it. Such drugs
could free humanity from such ancient horrors as schistosomiasis and leprosy,
and from new ones such as AIDS.
Drug companies are already redesigning molecules based on
knowledge of how they work. Researchers at Upjohn Company have designed and made
modified molecules of vasopressin, a hormone that consists of a short chain of
amino acids. Vasopressin increases the work done by the heart and decreases the
rate at which the kidneys produce urine; this increases blood pressure. The
researchers designed modified vasopressin molecules that affected receptor
molecules in the kidney more than those in the heart, giving them more specific
and controllable medical effects. More recently, they designed a modified
vasopressin molecule that binds to the kidney's receptor molecules without
direct effect, thus blocking and inhibiting the action of natural vasopressin.
Medical needs will push this work forward, encouraging researchers
to take further steps toward protein design and molecular engineering. Medical,
military, and economic pressures all push us in the same direction. Even before
the assembler breakthrough, molecular technology will bring impressive advances
in medicine; trends in biotechnology guarantee it. Still, these advances will
generally be piecemeal and hard to predict, each exploiting some detail of
biochemistry. Later, when we apply assemblers and technical AI systems to
medicine, we will gain broader abilities that are easier to foresee.
To understand these abilities, consider cells and their
self-repair mechanisms. In the cells of your body, natural radiation and noxious
chemicals split molecules, producing reactive molecular fragments. These can
misbond to other molecules in a process called cross-linking. As bullets and
blobs of glue would damage a machine, so radiation and reactive fragments damage
cells, both breaking molecular machines and gumming them up.
If your cells could not repair themselves, damage would rapidly
kill them or make them run amok by damaging their control systems. But evolution
has favored organisms with machinery able to do something about this problem.
The self-replicating factory system sketched in Chapter 4 repaired itself by
replacing damaged parts; cells do the same. So long as a cell's DNA remains
intact, it can make error-free tapes that direct ribosomes to assemble new
protein machines.
Unfortunately for us, DNA itself becomes damaged, resulting in
mutations. Repair enzymes compensate somewhat by detecting and repairing certain
kinds of damage to DNA. These repairs help cells survive, but existing repair
mechanisms are too simple to correct all problems, either in DNA or elsewhere.
Errors mount, contributing to the aging and death of cells - and of people.
Life, Mind, and Machines
Does it make sense to describe cells as "machinery," whether
self-repairing or not? Since we are made of cells, this might seem to reduce
human beings to "mere machines," conflicting with a holistic understanding of
life.
But a dictionary definition of holism is "the theory that reality
is made up of organic or unified wholes that are greater than the simple sum of
their parts." This certainly applies to people: one simpler sum of our parts
would resemble hamburger, lacking both mind and life.
The human body includes some ten thousand billion billion protein
parts, and no machine so complex deserves the label - mere." Any brief
description of so complex a system cannot avoid being grossly incomplete, yet at
the cellular level a description in terms of machinery makes sense. Molecules
have simple moving parts, and many act like familiar types of machinery. Cells
considered as a whole may seem less mechanical, yet biologists find it useful to
describe them in terms of molecular machinery.
Biochemists have unraveled what were once the central mysteries of
life, and have begun to fill in the details. They have traced how molecular
machines break food molecules into their building blocks and then reassemble
these parts to build and renew tissue. Many details of the structure of human
cells remain unknown (single cells have billions of large molecules of thousands
of different kinds), but biochemists have mapped every part of some viruses.
Biochemical laboratories often sport a large wall chart showing how the chief
molecular building blocks flow through bacteria. Biochemists understand much of
the process of life in detail, and what they don't understand seems to operate
on the same principles. The mystery of heredity has become the industry of
genetic engineering. Even embryonic development and memory are being explained
in terms of changes in biochemistry and cell structure.
In recent decades, the very quality of our remaining ignorance has
changed. Once, biologists looked at the process of life and asked, "How can this
be?" But today they understand the general principles of life, and when they
study a specific living process they commonly ask, "Of the many ways this could
be, which has nature chosen?" In many instances their studies have narrowed the
competing explanations to a field of one. Certain biological processes - the
coordination of cells to form growing embryos, learning brains, and reacting
immune systems - still present a real challenge to the imagination. Yet this is
not because of some deep mystery about how their parts work, but because of the
immense complexity of how their many parts interact to form a whole.
Cells obey the same natural laws that describe the rest of the
world. Protein machines in the right molecular environment will work whether
they remain in a functioning cell or whether the rest of the cell was ground up
and washed away days before. Molecular machines know nothing of "life" and
"death."
Biologists - when they bother - sometimes define life as the
ability to grow, replicate, and respond to stimuli. But by this standard, a
mindless system of replicating factories might qualify as life, while a
conscious artificial intelligence modeled on the human brain might not. Are
viruses alive, or are they "merely" fancy molecular machines? No experiment can
tell, because nature draws no line between living and nonliving. Biologists who
work with viruses instead ask about viability: "Will this virus function, if
given a chance?" The labels of "life" and "death" in medicine depend on medical
capabilities: physicians ask, "Will this patient function, if we do our best?"
Physicians once declared patients dead when the heart stopped; they now declare
patients dead when they despair of restoring brain activity. Advances in cardiac
medicine changed the definition once; advances in brain medicine will change it
again.
Just as some people feel uncomfortable with the idea of machines
thinking, so some feel uncomfortable with the idea that machines underlie our
own thinking. The word "machine" again seems to conjure up the wrong image, a
picture of gross, clanking metal, rather than signals flickering through a
shifting weave of neural fibers, through a living tapestry more intricate than
the mind it embodies can fully comprehend. The brain's really machinelike
machines are of molec ular size, smaller than the finest fibers.
A whole need not resemble its parts. A solid lump scarcely
resembles a dancing fountain, yet a collection of solid, lumpy molecules forms
fluid water. In a similar way, billions of molecular machines make up neural
fibers and synapses, thousands of fibers and synapses make up a neural cell,
billions of neural cells make up the brain, and the brain itself embodies the
fluidity of thought.
To say that the mind is "just molecular machines" is like saying
that the Mona Lisa is "just dabs of paint." Such statements confuse the parts
with the whole, and confuse matter with the pattern it embodies. We are no less
human for being made of molecules.
From Drugs to Cell Repair Machines
Being made of molecules, and having a human concern for our
health, we will apply molecular machines to biomedical technology. Biologists
already use antibodies to tag proteins, enzymes to cut and splice DNA, and viral
syringes (like the T4 phage) to inject edited DNA into bacteria. In the future,
they will use assembler-built nanomachines to probe and modify cells.
With tools like disassemblers, biologists will be able to study
cell structures in ultimate, molecular detail. They then will catalog the
hundreds of thousands of kinds of molecules in the body and map the structure of
the hundreds of kinds of cells. Much as engineers might compile a parts list and
make engineering drawings for an automobile, so biologists will describe the
parts and structures of healthy tissue. By that time, they will be aided by
sophisticated technical AI systems.
Physicians aim to make tissues healthy, but with drugs and surgery
they can only encourage tissues to repair themselves. Molecular machines will
allow more direct repairs, bringing a new era in medicine.
To repair a car, a mechanic first reaches the faulty assembly,
then identifies and removes the bad parts, and finally rebuilds or replaces
them. Cell repair will involve the same basic tasks - tasks that living systems
already prove possible.
Access: White blood cells leave the bloodstream and move through
tissue, and viruses enter cells. Biologists even poke needles into cells without
killing them. These examples show that molecular machines can reach and enter
cells.
Recognition: Antibodies and the tail fibers of the T4 phage - and
indeed, all specific biochemical interactions - show that molecular systems can
recognize other molecules by touch.
Disassembly: Digestive enzymes (and other, fiercer chemicals) show
that molecular systems can disassemble damaged molecules.
Rebuilding: Replicating cells show that molecular systems can
build or rebuild every molecule found in a cell.
Reassembly: Nature also shows that separated molecules can be put
back together again. The machinery of the T4 phage, for example, self-assembles
from solution, apparently aided by a single enzyme. Replicating cells show that
molecular systems can assemble every system found in a cell.
Thus, nature demonstrates all the basic operations that are needed
to perform molecular-level repairs on cells. What is more, as I described in
Chapter 1, systems based on nanomachines will generally be more compact and
capable than those found in nature. Natural systems show us only lower bounds to
the possible, in cell repair as in everything else.
Cell Repair Machines
In short, with molecular technology and technical AI we will
compile complete, molecular-level descriptions of healthy tissue, and we will
build machines able to enter cells and to sense and modify their structures.
Cell repair machines will be comparable in size to bacteria and
viruses, but their more-compact parts will allow them to be more complex. They
will travel through tissue as white blood cells do, and enter cells as viruses
do - or they could open and close cell membranes with a surgeon's care. Inside a
cell, a repair machine will first size up the situation by examining the cell's
contents and activity, and then take action. Early cell repair machines will be
highly specialized, able to recognize and correct only a single type of
molecular disorder, such as an enzyme deficiency or a form of DNA damage. Later
machines (but not much later, with advanced technical AI systems doing the
design work) will be programmed with more general abilities.
Complex repair machines will need nanocomputers to guide them. A
micron-wide mechanical computer like that described in Chapter 1 will fit in
1/1000 of the volume of a typical cell, yet will hold more information than does
the cell's DNA. In a repair system, such computers will direct smaller, simpler
computers, which will in turn direct machines to examine, take apart, and
rebuild damaged molecular structures.
By working along molecule by molecule and structure by structure,
repair machines will be able to repair whole cells. By working along cell by
cell and tissue by tissue, they (aided by larger devices, where need be) will be
able to repair whole organs. By working through a person organ by organ, they
will restore health. Because molecular machines will be able to build molecules
and cells from scratch, they will be able to repair even cells damaged to the
point of complete inactivity. Thus, cell repair machines will bring a
fundamental breakthrough: they will free medicine from reliance on self-repair
as the only path to healing.
To visualize an advanced cell repair machine, imagine it - and a
cell - enlarged until atoms are the size of small marbles. On this scale, the
repair machine's smallest tools have tips about the size of your fingertips; a
medium-sized protein, like hemoglobin, is the size of a typewriter; and a
ribosome is the size of a washing machine. A single repair device contains a
simple computer the size of a small truck, along with many sensors of protein
size, several manipulators of ribosome size, and provisions for memory and
motive power. A total volume ten meters across, the size of a three-story house,
holds all these parts and more. With parts the size of marbles packing this
volume, the repair machine can do complex things.
But this repair device does not work alone. It, like its many
siblings, is connected to a larger computer by means of mechanical data links
the diameter of your arm. On this scale, a cubic-micron computer with a large
memory fills a volume thirty stories high and as wide as a football field. The
repair devices pass it information, and it passes back general instructions.
Objects so large and complex are still small enough: on this scale, the cell
itself is a kilometer across, holding one thousand times the volume of a
cubic-micron computer, or a million times the volume of a single repair device.
Cells are spacious.
Will such machines be able to do everything necessary to repair
cells? Existing molecular machines demonstrate the ability to travel through
tissue, enter cells, recognize molecular structures, and so forth, but other
requirements are also important. Will repair machines work fast enough? If they
do, will they waste so much power that the patient will roast?
The most extensive repairs cannot require vastly more work than
building a cell from scratch. Yet molecular machinery working within a cellular
volume routinely does just that, building a new cell in tens of minutes (in
bacteria) to a few hours (in mammals). This indicates that repair machinery
occupying a few percent of a cells volume will be able to complete even
extensive repairs in a reasonable time - days or weeks at most. Cells can spare
this much room. Even brain cells can still function when an inert waste called
lipofuscin (apparently a product of molecular damage) fills over ten percent of
their volume.
Powering repair devices will be easy: cells naturally contain
chemicals that power nanomachinery. Nature also shows that repair machines can
be cooled: the cells in your body rework themselves steadily, and young animals
grow swiftly without cooking themselves. Handling heat from a similar level of
activity by repair machines will be no sweat - or at least not too much sweat,
if a week of sweating is the price of health.
All these comparisons of repair machines to existing biological
mechanisms raise the question of whether repair machines will be able to improve
on nature. DNA repair provides a clear-cut illustration.
Just as an illiterate "book-repair machine" could recognize and
repair a torn page, so a cell's repair enzymes can recognize and repair breaks
and cross-links in DNA. Correcting misspellings (or mutations), though, would
require an ability to read. Nature lacks such repair machines, but they will be
easy to build. Imagine three identical DNA molecules, each with the same
sequence of nucleotides. Now imagine each strand mutated to change a few
scattered nucleotides. Each strand still seems normal, taken by itself.
Nonetheless, a repair machine could compare each strand to the others, one
segment at a time, and could note when a nucleotide failed to match its mates.
Changing the odd nucleotide to match the other two will then repair the damage.
This method will fail if two strands mutate in the same spot.
Imagine that the DNA of three human cells has been heavily damaged - after
thousands of mutations, each cell has had one in every million nucleotides
changed. The chance of our three-strand correction procedure failing at any
given spot is then about one in a million million. But compare five strands at
once, and the odds become about one in a million million million, and so on. A
device that compares many strands will make the chance of an uncorrectable error
effectively nil.
In practice, repair machines will compare DNA molecules from
several cells, make corrected copies, and use these as standards for
proofreading and repairing DNA throughout a tissue. By comparing several
strands, repair machines will dramatically improve on nature's repair enzymes.
Other repairs will require different information about healthy
cells and about how a particular damaged cell differs from the norm. Antibodies
identify proteins by touch, and properly chosen antibodies can generally
distinguish any two proteins by their differing shapes and surface properties.
Repair machines will identify molecules in a similar way. With a suitable
computer and data base, they will be able to identify proteins by reading their
amino acid sequences.
Consider a complex and capable repair system. A volume of two
cubic microns - about 2/1000 of the volume of a typical cell - will be enough to
hold a central data base system able to:
1) Swiftly identify any of the hundred thousand or so different
human proteins by examining a short amino acid sequence.
2) Identify all the other complex molecules normally found in
cells.
3) Record the type and position of every large molecule in the
cell.
Each of the smaller repair devices (of perhaps thousands in a
cell) will include a less capable computer. Each of these computers will be able
to perform over a thousand computational steps in the time that a typical enzyme
takes to change a single molecular bond, so the speed of computation possible
seems more than adequate. Because each computer will be in communication with a
larger computer and the central data base, the available memory seems adequate.
Cell repair machines will have both the molecular tools they need and "brains"
enough to decide how to use them.
Such sophistication will be overkill (overcure?) for many health
problems. Devices that merely recognize and destroy a specific kind of cell, for
example, will be enough to cure a cancer. Placing a computer network in every
cell may seem like slicing butter with a chain saw, but having a chain saw
available does provide assurance that even hard butter can be sliced. It seems
better to show too much than too little, if one aims to describe the limits of
the possible in medicine.
Some Cures
The simplest medical applications of nanomachines will involve not
repair but selective destruction. Cancers provide one example; infectious
diseases provide another. The goal is simple: one need only recognize and
destroy the dangerous replicators, whether they are bacteria, cancer cells,
viruses, or worms. Similarly, abnormal growths and deposits on arterial walls
cause much heart disease; machines that recognize, break down, and dispose of
them will clear arteries for more normal blood flow. Selective destruction will
also cure diseases such as herpes in which a virus splices its genes into the
DNA of a host cell. A repair device will enter the cell, read its DNA, and
remove the addition that spells "herpes."
Repairing damaged, cross-linked molecules will also be fairly
straightforward. Faced with a damaged, cross-linked protein, a cell repair
machine will first identify it by examining short amino acid sequences, then
look up its correct structure in a data base. The machine will then compare the
protein to this blueprint, one amino acid at a time. Like a proofreader finding
misspellings and strange characters (char#cters), it will find any changed amino
acids or improper cross-links. By correcting these flaws, it will leave a normal
protein, ready to do the work of the cell.
Repair machines will also aid healing. After a heart attack, scar
tissue replaces dead muscle. Repair machines will stimulate the heart to grow
fresh muscle by resetting cellular control mechanisms. By removing scar tissue
and guiding fresh growth, they will direct the healing of the heart.
This list could continue through problem after problem (Heavy
metal poisoning? - Find and remove the metal atoms) but the conclusion is easy
to summarize. Physical disorders stem from mis-arranged atoms; repair machines
will be able to return them to working order, restoring the body to health.
Rather than compiling an endless list of curable diseases (from arthritis,
bursitis, cancer, and dengue to yellow fever and zinc chills and back again), it
makes sense to look for the limits to what cell repair machines can do. Limits
do exist.
Consider stroke, as one example of a problem that damages the
brain. Prevention will be straightforward: Is a blood vessel in the brain
weakening, bulging, and apt to burst? Then pull it back into shape and guide the
growth of reinforcing fibers. Does abnormal clotting threaten to block
circulation? Then dissolve the clots and normalize the blood and blood-vessel
linings to prevent a recurrence. Moderate neural damage from stroke will also be
repairable: if reduced circulation has impaired function but left cell
structures intact, then restore circulation and repair the cells, using their
structures as a guide in restoring the tissue to its previous state. This will
not only restore each cell's function, but will preserve the memories and skills
embodied in the neural patterns in that part of the brain.
Repair machines will be able to regenerate fresh brain tissue even
where damage has obliterated these patterns. But the patient would lose old
memories and skills to the extent that they resided in that part of the brain.
If unique neural patterns are truly obliterated, then cell repair machines could
no more restore them than art conservators could restore a tapestry from stirred
ash. Loss of information through obliteration of structure imposes the most
important, fundamental limit to the repair of tissue.
Other tasks are beyond cell repair machines for different reasons
- maintaining mental health, for instance. Cell repair machines will be able to
correct some problems, of course. Deranged thinking sometimes has biochemical
causes, as if the brain were drugging or poisoning itself, and other problems
stem from tissue damage. But many problems have little to do with the health of
nerve cells and everything to do with the health of the mind.
A mind and the tissue of its brain are like a novel and the paper
of its book. Spilled ink or flood damage may harm the book, making the novel
difficult to read. Book repair machines could nonetheless restore physical -
health" by removing the foreign ink or by drying and repairing the damaged paper
fibers. Such treatments would do nothing for the book's content, however, which
in a real sense is nonphysical. If the book were a cheap romance with a moldy
plot and empty characters, repairs would be needed not on the ink and paper, but
on the novel. This would call not for physical repairs, but for more work by the
author, perhaps with advice.
Similarly, removing poisons from the brain and repairing its nerve
fibers will thin some mental fogs, but not revise the content of the mind. This
can be changed by the patient, with effort; we are all authors of our minds. But
because minds change themselves by changing their brains, having a healthy brain
will aid sound thinking more than quality paper aids sound writing.
Readers familiar with computers may prefer to think in terms of
hardware and software. A machine could repair a computer's hardware while
neither understanding nor changing its software
Such machines might stop the computer's activity but leave the
patterns in memory intact and ready to work again. In computers with the right
kind of memory (called "nonvolatile"), users do this by simply switching off the
power. In the brain the job seems more complex, yet there could be medical
advantages to inducing a similar state.
Anesthesia Plus
Physicians already stop and restart consciousness by interfering
with the chemical activity that underlies the mind. Throughout active life,
molecular machines in the brain process molecules. Some disassemble sugars,
combine them with oxygen, and capture the energy this releases. Some pump salt
ions across cell membranes; others build small molecules and release them to
signal other cells. Such processes make up the brain's metabolism, the sum total
of its chemical activity. Together with its electrical effects, this metabolic
activity underlies the changing patterns of thought.
Surgeons cut people with knives. In the mid-1800s, they learned to
use chemicals that interfere with brain metabolism, blocking conscious thought
and preventing patients from objecting so vigorously to being cut. These
chemicals are anesthetics. Their molecules freely enter and leave the brain,
allowing anesthetists to interrupt and restart human consciousness.
People have long dreamed of discovering a drug that interferes
with the metabolism of the entire body, a drug able to interrupt metabolism
completely for hours, days, or years. The result would be a condition of
biostasis (from bio, meaning life, and stasis, meaning a stoppage or a stable
state). A method of producing reversible biostasis could help astronauts on long
space voyages to save food and avoid boredom, or it could serve as a kind of
one-way time travel. In medicine, biostasis would provide a deep anesthesia
giving physicians more time to work. When emergencies occur far from medical
help, a good biostasis procedure would provide a sort of universal first-aid
treatment: it would stabilize a patient's condition and prevent molecular
machines from running amok and damaging tissues.
But no one has found a drug able to stop the entire metabolism the
way anesthetics stop consciousness - that is, in a way that can be reversed by
simply washing the drug out of the patient's tissues. Nonetheless, reversible
biostasis will be possible when repair machines become available.
To see how one approach would work, imagine that the blood stream
carries simple molecular devices to tissues, where they enter the cells. There
they block the molecular machinery of metabolism - in the brain and elsewhere -
and tie structures together with stabilizing cross-links. Other molecular
devices then move in, displacing water and packing themselves solidly around the
molecules of the cell. These steps stop metabolism and preserve cell structures.
Because cell repair machines will be used to reverse this process, it can cause
moderate molecular damage and yet do no lasting harm. With metabolism stopped
and cell structures held firmly in place, the patient will rest quietly,
dreamless and unchanging, until repair machines restore active life.
If a patient in this condition were turned over to a present-day
physician ignorant of the capabilities of cell repair machines, the consequences
would likely be grim. Seeing no signs of life, the physician would likely
conclude that the patient was dead, and then would make this judgment a reality
by "prescribing" an autopsy, followed by burial or burning.
But our imaginary patient lives in an era when biostasis is known
to be only an interruption of life, not an end to it. When the patient's
contract says "wake me!" (or the repairs are complete, or the flight to the
stars is finished), the attending physician begins resuscitation. Repair
machines enter the patient's tissues, removing the packing from around the
patient's molecules and replacing it with water. They then remove the
cross-links, repair any damaged molecules an structures, and restore normal
concentrations of salts, blood sugar, ATP, and so forth. Finally, they unblock
the metabolic machinery. The interrupted metabolic processes resume, the patient
yawns, stretches, sits up, thanks the doctor, checks the date, and walks out the
door.
From Function To Structure
The reversibility of biostasis and irreversibility of severe
stroke damage help to show how cell repair machines will change medicine. Today,
physicians can only help tissues to heal themselves. Accordingly they must try
to preserve the function of tissue. If tissues cannot function, they cannot
heal. Worse, unless they are preserved, deterioration follows, ultimately
obliterating structure. It is as if a mechanic's tools were able to work only on
a running engine.
Cell repair machines change the central requirement from
preserving function to preserving structure. As I noted in the discussion of
stroke, repair machines will be able to restore brain function with memory and
skills intact only if the distinctive structure of the neural fabric remains
intact. Biostasis involves preserving neural structure while deliberately
blocking function.
All this is a direct consequence of the molecular nature of the
repairs. Physicians using scalpels and drugs can no more repair cells than
someone using only a pickax and a can of oil can repair a fine watch. In
contrast, having repair machines and ordinary nutrients will be like having a
watchmaker's tools and an unlimited supply of spare parts. Cell repair machines
will change medicine at its foundations.
From Treating Disease To Establishing Health
Medical researchers now study diseases, often seeking ways to
prevent or reverse them by blocking a key step in the disease process. The
resulting knowledge has helped physicians greatly: they now prescribe insulin to
compensate for diabetes, anti-hypertensives to prevent stroke, penicillin to
cure infections, and so on down an impressive list. Molecular machines will aid
the study of diseases, yet they will make understanding disease far less
important. Repair machines will make it more important to understand health.
The body can be ill in more ways than it can be healthy. Healthy
muscle tissue, for example, varies in relatively few ways: it can be stronger or
weaker, faster or slower, have this antigen or that one, and so forth. Damaged
muscle tissue can vary in all these ways, yet also suffer from any combination
of strains, tears, viral infections, parasitic worms, bruises, punctures,
poisons, sarcomas, wasting diseases, and congenital abnormalities. Similarly,
though neurons are woven in as many patterns as there are human brains,
individual synapses and dendrites come in a modest range of forms - if they are
healthy.
Once biologists have described normal molecules, cells, and
tissues, properly programmed repair machines will be able to cure even unknown
diseases. Once researchers describe the range of structures that (for example) a
healthy liver may have, repair machines exploring a malfunctioning liver need
only look for differences and correct them. Machines ignorant of a new poison
and its effects will still recognize it as foreign and remove it. Instead of
fighting a million strange diseases, advanced repair machines will establish a
state of health.
Developing and programming cell repair machines will require great
effort, knowledge, and skill. Repair machines with broad capabilities seem
easier to build than to program. Their programs must contain detailed knowledge
of the hundreds of kinds of cells and the hundreds of thousands of kinds of
molecules in the human body. They must be able to map damaged cellular
structures and decide how to correct them. How long will such machines and
programs take to be developed? Offhand, the state of biochemistry and its
present rate of advance might suggest that the basic knowledge alone will take
centuries to collect. But we must beware of the illusion that advances will
arrive in isolation.
Repair machines will sweep in with a wave of other technologies.
The assemblers that build them will first be used to build instruments for
analyzing cell structures. Even a pessimist might agree that human biologists
and engineers equipped with these tools could build and program advanced cell
repair machines in a hundred years of steady work. A cocksure, far-seeing
pessimist might say a thousand years. A really committed nay-sayer might declare
that the job would take people a million years. Very well: fast technical AI
systems - a millionfold faster than scientists and engineers - will then develop
advanced cell repair machines in a single calendar year.
A Disease Called "Aging"
Aging is natural, but so were smallpox and our efforts to prevent
it. We have conquered smallpox, and it seems that we will conquer aging.
Longevity has increased during the last century, but chiefly
because better sanitation and drugs have reduced bacterial illness. The basic
human life span has increased little.
Still, researchers have made progress toward understanding and
slowing the aging process. They have identified some of its causes, such as
uncontrolled cross-linking. They have devised partial treatments, such as
antioxidants and free-radical inhibitors. They have proposed and studied other
mechanisms of aging, such as - clocks" in the cell and changes in the body's
hormone balance. In laboratory experiments, special drugs and diets have
extended the life span of mice by 25 to 45 percent.
Such work will continue; as the baby boom generation ages, expect
a boom in aging research. One biotechnology company, Senetek of Denmark,
specializes in aging research. In April 1985, Eastman Kodak and ICN
Pharmaceuticals were reported to have joined in a $45 million venture to produce
isoprinosine and other drugs with the potential to extend life span. The results
of conventional anti-aging research may substantially lengthen human life spans
- and improve the health of the old - during the next ten to twenty years. How
greatly will drugs, surgery, exercise, and diet extend life spans? For now,
estimates must remain guesswork. Only new scientific knowledge can rescue such
predictions from the realm of speculation, because they rely on new science and
not just new engineering.
With cell repair machines, however, the potential for life
extension becomes clear. They will be able to repair cells so long as their
distinctive structures remain intact, and will be able to replace cells that
have been destroyed. Either way, they will restore health. Aging is
fundamentally no different from any other physical disorder; it is no magical
effect of calendar dates on a mysterious life-force. Brittle bones, wrinkled
skin, low enzyme activities, slow wound healing, poor memory, and the rest all
result from damaged molecular machinery, chemical imbalances, and mis-arranged
structures. By restoring all the cells and tissues of the body to a youthful
structure, repair machines will restore youthful health.
People who survive intact until the time of cell repair machines
will have the opportunity to regain youthful health and to keep it almost as
long as they please. Nothing can make a person (or anything else) last forever,
of course, but barring severe accidents, those wishing to do so will live for a
long, long time.
As a technology develops, there comes a time when its principles
become clear, and with them many of its consequences. The principles of rocketry
were clear in the 1930s, and with them the consequence of spaceflight. Filling
in the details involved designing and testing tanks, engines, instruments, and
so forth. By the early 1950s, many details were known. The ancient dream of
flying to the Moon had became a goal one could plan for.
The principles of molecular machinery are already clear, and with
them the consequence of cell repair machines. Filling in the details will
involve designing molecular tools, assemblers, computers, and so forth, but many
details of existing molecular machines are known today. The ancient dream of
achieving health and long life has become a goal one can plan for.
Medical research is leading us, step by step, along a path toward
molecular machinery. The global competition to make better materials,
electronics, and biochemical tools is pushing us in the same direction. Cell
repair machines will take years to develop, but they lie straight ahead.
They will bring many abilities, both for good and for ill. A
moment's thought about military replicators with abilities like those of cell
repair machines is enough to turn up nauseating possibilities. Later I will
describe how we might avoid such horrors, but it first seems wise to consider
the alleged benefits of cell repair machines. Is their apparent good really
good? How might long life affect the world?
by K. Eric Drexler
Published for the WWW
by Russell Whitaker
http://www.foresight.org/EOC/EOC_Chapter_7.html
From Drugs to Cell Repair
Machines
Cell Repair Machines
Some Cures
Anesthesia Plus
From
Function To Structure
From Treating Disease To Establishing Health
A
Disease Called "Aging"
http://www.foresight.org/EOC/EOC_References.html#Ch_7
- KARL K. DARROW, The
Renaissance of Physics