Engines of Creation © Copyright 1986, . All rights reserved. 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