Borderlands of Science

by Charles Sheffield

  If you do say that, you'll be right. It wasn't. There are more people in the world today than ever before. Next year there will be more yet.

  Here are some sobering numbers: At the time of the birth of Christ, the world population was around two hundred million. By 1800 that number had climbed to one billion. Two billion was reached about 1930; three billion in 1960; four billion in 1975; five billion in 1988. By 2000 the population topped six billion.

  Not only more and more, but faster and faster. People are living longer and the old equalizers, famine and plague, seem largely under control. War remains, but the two great conflicts of the twentieth century did little to slow the growth in population. It took a hundred and thirty years to add the second billion, only twelve years to add the sixth. With any simple-minded projection for the next century apparently zooming to infinity, we have to ask, how long can this go on? Also, where will all the new people fit? Not, we hope, on the commuter routes that we use.

  A glance at a population map at first seems reassuring. Most of the world still looks empty. A second glance, and you realize why. Of the Earth's total land area, one fifth is too cold to grow crops, another fifth is too dry, a fifth is too high, and another seventh has infertile soils. Only about a quarter of the land is good for farming. Empty areas of the planet are empty for good reason.

  That can change, and is already changing. Sunlight is available everywhere, regardless of how high or cold the land. Plants are remarkably efficient factories for converting sunlight, water, and carbon dioxide into food. By genetic engineering, we are producing new crop varieties with shorter growing seasons and more tolerance of cold, drought and high salinity. In the future, it seems certain that areas of the globe now empty will be able to fill with high-yield food crops, and then with people.

  According to projections, they will have to. Population estimates for the year 2050 range from eight to twelve billion, for 2100 from ten to fifteen billion. Even these numbers are nowhere near the limit. Provided that we can produce the food (and distribute it), the Earth can easily support as many as twenty billion people—almost four times as many as we have today.

  The question you may ask, sitting in your car on a freeway that has become one giant parking lot, is a different one. Sure, if we struggle and squeeze, maybe we can handle four times the present population. But do we want to? How many people is enough?

  A.6. The inside view. Last week I had to go for a CAT scan of my abdomen. It was nothing special, more a loss of dignity than anything else. But it was still an indignity, still uncomfortable, still invasive (I had to swallow a barium milk shake that tasted like glue). Most people hate the standard medical routines. We don't like lying semi-naked on a slab, or having blood taken, or the prospect of the insertion of mechanical devices into veins, sinuses, bronchial tubes, urethras, and other personal apertures.

  How might we improve all this? Before we get to that, let's recall the past—and things far worse than anything that will happen to me next week.

  Until a hundred years ago a doctor had few tools to examine a patient's interior. A stethoscope to listen to body processes, a thermometer to measure body temperature, a spatula to examine tongue and throat, and that was about it. The rest of the diagnosis relied on palpation (feeling you), tapping, external symptoms such as ulcers and rashes, and the appearance of various waste products. If all those failed, the dreaded next step could be "exploratory surgery," with or without anesthetics.

  And then, as though by magic, in the last decade of the nineteenth century a device came along that could actually see inside a human body. True, the X-ray was better at viewing bones and hard tissue than organs and soft tissue, but it was an enormous step forward.

  The X-ray was the first "modern" tool of diagnosis. Since then we have developed a variety of other methods for taking an inside look: the CAT scan, the MRI, and ultrasonic imaging. They permit three-dimensional images of both hard and soft tissues. Used in combination with the injection of special materials, they allow the operation of particular organs or the flow of substances through the body to be studied as they happen. The radioactive tracers used for this purpose are one undeniably positive fall-out of the nuclear age.

  Hand in hand with the images goes chemical diagnosis. Today, blood samples can provide a doctor with information about everything from liver function to diabetes to urinary infection to rheumatoid arthritis to AIDS to the presence of the particular bacterium (Helicobacter pylori) responsible for most stomach ulcers. Any tiny skin sample is sufficient to permit a DNA analysis, which can in turn warn of the presence of certain hereditary diseases and tendencies.

  We have come a long way in a hundred years. What about the next hundred?

  Completely non-invasive diagnosis, with superior imaging tools and with chemical tests that can operate without drawing blood, will become available in the next generation. The chemical tests will use saliva and urine samples, or work through the skin without puncturing it. For the digestive system, we may swallow a pill-sized object, which will quietly and unobtrusively observe and report on the whole alimentary canal as it passes along it.

  No more upper GI exams, no more sigmoidoscopies. Our grandchildren will regard today's invasions (drawing blood, taking bone marrow samples, or inserting objects into the body) the way we think of operations without anesthetics: part of the bad old days of the barbarous past.

  Or even the uncomfortable indignity of last week.

  A.7. Attack of the killer topatoes. Genetically modified vegetables are in the news. Should you eat these "genemods" (GMs, in England) or should you avoid them at all costs?

  Let's back up a bit. Your wife may not like it when you say that her brother is a louse. You explain to her, that's not really an insult. At the most basic level, down where it matters, a louse is not that different from a human being.

  How so? Your brother-in-law and the louse are made up of cells. So are you. In the middle of almost every cell is a smaller piece called the cell nucleus. Inside that, even smaller, are long strings of material called chromosomes. It's your chromosomes that decide what you are like, while the louse's decide what it is like.

  When you examine a human or a louse chromosome in detail they look remarkably similar. And it's not just the louse and your brother-in-law. It's everything you can think of, from snails to snakes to Susan Sarandon. All our chromosomes are made of the same basic stuff; and that stuff is what makes each of us, physically, what we are.

  This suggests a neat idea. Suppose we have a variety of tomato that is very tasty and productive, but suffers from tomato wilt. We also have a wilt-resistant type of potato. The immunity is carried in a particular part of a potato chromosome (let's call it a "gene"). If we could snip just that gene out, and insert it into the tomato chromosome, we might be able to create a new something—call it a "topato"—that produces great tomatoes and doesn't suffer from wilt.

  We are not quite that smart yet, although with some foods we are well on the way. Do you believe you have never eaten genetically modified foods? Then take a look at the boxes and containers in your kitchen. See if they contain soy (most of them do). Today nearly half of the US soybean crop is a genetically engineered variety. Crops with genetic modification can have a higher yield, or an extra vitamin, or greater tolerance for weedkillers, bacteria, or salty soil. The variations are endless, and the topato I'm describing is a real possibility.

  Should we worry about all this? I think we should be careful. We are making things that never existed in Nature. Maybe a "Frankenstein tomato" could have new properties that never occurred to us when we were making it.

  On the other hand, plant and animal breeders have been playing this game, through cross-breeding, for thousands of years. There was no such thing as a nectarine or a loganberry before a human developed them, but we eat them quite happily. Even if we hadn't made such things, nature has a way of trying so many different combinations that they might occur naturally in time.

 
My only concern is that we may be, as usual, in a bit too much of a hurry. We are duplicating in a few years a process that in nature would normally take millions; and we, unlike nature, have to explain our mistakes.

  A.8. Twinkle, twinkle? "It's not the things we don't know that causes the trouble, it's the things we know that ain't so." I love that quote and I wish I'd said it first, but Artemus Ward beat me to it by about a hundred and fifty years.

  Less than fifty years ago, one thing every astronomer "knew" was that there was a limit to what a telescope could see when looking out into space. If you made a telescope's main lens or mirror bigger and bigger, it would collect more and more light but the degree of detail of what you saw would not increase. The limiting mirror or lens size is quite small, about ten inches, and beyond that you will get a brighter but not a sharper image.

  The problem is nothing to do with the telescope's design or manufacture. The spoiler is the Earth's atmosphere, which is in constant small-scale turbulence. The moving air distorts the path of the light rays traveling through it, so that instead of appearing as a steady, sharp image, the target seems to be in small, random motion. The nursery rhyme has it right. When the target looks small, like a star, it will twinkle; when it is larger and more diffuse, like a planet or galaxy, fine detail will be blurred.

  Twenty years ago that was the end of the story. If you wanted highly detailed images of objects in space, you had to place your telescope outside the Earth's atmosphere. That idea led to the orbiting Hubble Space Telescope, whose wonderful images have appeared on every TV channel and in every magazine. The Hubble pictures are far more detailed than any obtained by a telescope down here on Earth, even though the size of the Hubble's mirror, at 94 inches, is much smaller than the 200-inch mirror at Mount Palomar. The only road to detailed images of astronomical objects was surely the high road, through telescopes placed in orbit.

  This "fact" turned out to be one of the things we know that ain't so. About fifteen years ago, a small group of scientists working on a quite different problem for the Strategic Defense Initiative ("Star Wars" to most people) came up with the idea of aiming a laser beam upward and measuring the way that its path was distorted in the atmosphere. Knowing what happened to the laser beam, the focus of the observing telescope mirror could be continuously (and rapidly) changed, so as to compensate for the changes in light path. The procedure, known as "adaptive optics," was tried. It worked, spectacularly well. Today, ground-based telescopes are obtaining images of a crispness and clarity that a generation ago would have been considered impossible.

  What else do we "know" that can't be done with ground-based telescopes today? Well, the Earth's atmosphere completely absorbs light of certain wavelengths. If we want to learn what is happening in space at those wavelengths, we still need orbiting telescopes. I certainly believe that is true. On the other hand, it may be just one more thing I know that ain't so.

  A.9. Are you a cyborg? At the turn of the millennium, I get asked one question over and over: What's going to happen to us? How will we change, as humans, when science and technology advance over the years and the centuries?

  The only honest answer is, I don't know; but I am willing to stick my neck out and make a prediction in one specific area: we will all become, more and more, cyborgs.

  A cyborg is a human being, changed to improve or restore body functions by the addition or replacement of man-made parts. Almost everyone reading this is already a cyborg in one or more ways. Are you wearing eyeglasses or contact lenses? Do you have dental fillings, or a crown on a tooth? Are you perhaps wearing a hearing aid, or a pacemaker, or is one of your knee, hip, or shoulder joints artificial? Has part of a vein or artery been replaced by a plastic tube?

  If your answer to any of these questions is yes, then you are part cyborg. Admittedly, these are cyborg additions at the most primitive level, but we already have the technology to make much more versatile and radical changes to ourselves.

  Let's consider a few of the easy ones. First, we can make an artificial eye lens containing miniature motors, sensors, and a tiny computer. The lens will adapt, just like a human eye lens, to changes in light levels and in the distance of the object being viewed. Near-sightedness, far-sightedness and astigmatism will become history. As the human retina ages, or light levels become low, the lens can also boost the contrast of scenes to compensate. Everyone will have eyes like a hawk, able to see with great clarity, and eyes like a cat, able to see well in near-dark. Last night, driving an unfamiliar winding road through heavy snow, I would have given a lot for a pair of these future eye lenses.

  At first, of course, such things will cost a lot; millions of dollars for the prototypes. But, like hand calculators or cameras, once they are in mass production prices will fall dramatically. The main cost will be the one-time installation charge.

  Suppose that your eyes are excellent, and you have no need for cyborg eyes. What about your hearing? Today's hearing aids, despite the claims made for them, are rotten. They don't give directional hearing, and they can't separate what you want to hear from background noise. The next generation of hearing aids will also contain tiny computers. They will be invisibly small, provide full stereo directional hearing, and boost selected sound frequencies as necessary. They too will be expensive at first, but manufacturing costs will drop until they are cheap enough to throw away rather than repair.

  Your ears and eyes are in fine working shape, you say, so you don't need cyborg help? Very well. Here are a few other third millennium optional additions. You choose any items that appeal to you.

  Peristalsis control, to provide perfectly regular bowel habits. A sleep regulator, which can be set to make you fall asleep or awake according to your own preferred schedule. A general metabolic rate regulator, boosting or lowering body activity levels to match the situation (or the level of a partner; we probably all know couples who wage constant war over setting the thermostat). A blood flow controller, solving any possible problems of male impotence. A vocal cord monitor, which adjusts your rough shot at a note so you sing exactly in tune. Built-in computer chips, to provide instant answers to arithmetic and logical questions of all kinds.

  If this list worries you, and you say, isn't there a danger that devices like this will sometimes be abused or misused? I reply, can you think of any piece of technology that sometimes isn't?

  A.10. "You've got a virus." Sometimes I think that viruses were created mainly to benefit the medical profession.

  You're not feeling well, and you go to see your doctor. After an examination and a test or two, she says, "You're sick all right. You have an infection. But it isn't a bacterial infection, it's a viral infection. So there's no point in giving you antibiotics. Just go home and take it easy until you feel better." Meaning, "We're not quite sure what's wrong with you, but we do know we can't give you anything to cure it."

  Are viruses and bacteria really so different? On the face of it, they have a lot in common. They exist in large numbers everywhere, some forms serve as the agents for disease, and they are too small to be seen without a microscope. On closer inspection, however, viruses are much more mysterious objects than bacteria.

  First, although both are tiny, viruses are orders of magnitude smaller. The largest known bacterium is relatively huge, a bloated object as big as the period at the end of this sentence. Bacteria are complete living organisms, which reproduce themselves given only a supply of nutrients.

  By contrast, a virus is a tiny object, often less than a hundred-thousandth of an inch long. It is no more than a tiny piece of DNA or RNA, wrapped in a protein coat, and it cannot reproduce at all unless it can find and enter another organism with its own reproducing mechanism. It is different enough from all other life forms that some biologists argue that viruses are not really alive; certainly, they do not fit into any of the known biological kingdoms.

  The way in which a virus reproduces is highly ingenious. First, it must find and penetrate the wall of a normal healthy c
ell, often with the aid of a little tail of protein that serves as a kind of corkscrew or hypodermic syringe. Once inside, the virus takes over the cell's own reproducing equipment. It uses that equipment to make hundreds of thousands of copies of itself, until the chemical supplies within the cell are used up. Then the cell wall bursts open to release the viruses, which go on to repeat the process in another cell. Viruses are, and must be, parasitic on other life forms. They are the ultimate Man Who Came to Dinner, who does not leave until he has eaten everything in the house, and also killed his host.

  This explanation of what a virus is and does leads to a bigger mystery: Since a virus totally depends for its reproduction on the availability of other living organisms, how did viruses ever arise in the first place?

  Today's biology has no complete answer to this question. However, it seems to me that the only plausible explanation is that viruses were once complete organisms, probably bacteria with their own reproducing mechanisms. They found it advantageous to invade other cells, perhaps to rob them of nutrients. As time went on, the virus found that it could get by with less and less of its own cellular factories, and could more and more use the facilities of its host. Little by little the virus dispensed with its cell wall and its nutrient-producing facilities, and finally retained only the barest necessities needed to copy itself. What we see today is the result of a long process of evolution, which could perhaps more appropriately be called devolution. The end result is one of nature's most perfect creations, reproduction reduced to its absolute minimum.

  The virus is a lean, mean copying machine. It may be a comfort to remember this, the next time that you are laid low by what your doctor describes as a viral infection. And we can take greater comfort from the fact that, as our understanding increases, twenty years from now we should have "viral antibiotics" to tackle viruses and have us back on our feet within 24 hours.