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As far as Earth itself is concerned, space will become the major source of almost all human needs minerals from the moon, energy from the sun, and food from thechurning algal cells endlessly multiplying ("pie in the sky" at last).Must we have intact cells to produce food, for that matter?Chloroplasts (the chlorophyll-containing granules within plant cells) could be isolated and put to work on their own, performing their task more rapidly and with moresimple-minded efficiency, perhaps, than ordinary cells could.And if the chloroplasts are studied in detail, the chemical system may come to be so well-understood that it will become possible to mimic their workings in systemssimpler still.In short, we might be able to produce food through the agency of nonliving chemicals.It is doubtful that this could be quite as efficient as the complex living systemsfinely honed after billions of years of evolution.The nonliving chemical systems, however, would be less vulnerable to radiation, perhaps, and more easily adjustable tovarious conditions, such as higher or lower temperatures, or different wavelengths of light.Agriculture as such may eventually pass away.Food production may become a matter of chemical technology.Will we, then, no longer need plants?Nonsense! Again man does not live by bread alone.The plant world will always delight us for a variety of reasons; and if the amber waves of grain become lessimportant, there will be more room for pleasure in variety.Even small space settlements may then find they can develop and care for quite complex ecological balancesand may find themselves rejoicing in a diversity of plant species impossible under earlier conditions.48 Bacterial EngineeringGenetic engineering is not really something new.Human beings have been fiddling with genes for as long as ten thousand years.That's how long they have been growingplants and herding animals.Of course, in earlier times human beings had not even heard of genes, but it made reasonable sense to see to it that an unusually strong bull sired many calves and thatan unusually good milker mothered as many as possible; and, again, that one used the best strains of wheat for seed those that grew fastest or that yielded particularlyplump grains.In consequence, over the generations the plants and animals that humanity had domesticated came to change their characteristics in the directions human beings deemeddesirable.Horses are bigger, stronger, and faster than their prehistoric progenitors; cattle are more placid and yield more beef and milk; sheep yield more wool;chickens lay more eggs; turkeys have larger breasts; and so on.Animals can be bred for amusement, too.Think of some of the breeds of dogs and pigeons that exist.Nor does anyone ever consider what is good for the animals themselves.Many of them could no longer exist in the wild without human care.The corn plant could noteven reproduce without human help.Although human beings were not able to control the mating of smaller and simpler creatures in the same way they could the large plants and animals they haddomesticated, they did what they could to make use of their labors.They plundered beehives for honey and certain caterpillar cocoons for silk.They even put yeastcells to work fermenting fruit juices and soaked grain.All these things were done in prehistoric times.Oddly enough, humanity266267 Bacterial Engineeringin historic times has not succeeded in truly domesticating any new species of plant or animal.Perhaps that is because there has been no necessity for doing so.Whathas already been done seems to be enough.Yet there are directions in which we are making progress, and can make more in the future, directions undreamed of in earlier times.There are tiny organisms whose existence was not discovered until recent times 1,500 different species of bacteria.A few of those species cause disease, but thepercentage is low.Most bacteria do us no harm, and many of them are useful, even essential.Biochemically, the bacteria are amazingly versatile.There are no naturally produced materials that cannot be broken down by one type of bacteria or another.Decaybacteria restore everything to the biosphere to be used over again.If their work stopped, the world would become littered with undecayed scraps of indigestiblematter, and these would accumulate till all life stopped.Other bacteria can combine the nitrogen of the air with other elements to form substances that maintain the fertility of the soil.Without them, the soil and waters of theearth would slowly grow sterile.Bacteria can carry out chemical reactions that higher animals cannot, and we sometimes benefit by it.Bacteria in the stomach of cattle digest the cellulose of grass andhay (the cattle cannot do it all by themselves).The products of digestion are absorbed by cattle and eventually come back to us as meat, milk, cheese, and butter.Bacteria in our own intestines form some of the vitamins we can't make for ourselves.The question is: Can we tame bacteria? Can we carefully breed them into strains that are of even greater use to us than they are in nature?We can't do it by the ordinary breeding methods we use with larger animals, of course, since bacteria reproduce asexually.However, might we not isolate variousbacteria of a particular species, allow each to reproduce, then test each batch for some useful function, pick the one that performs most satisfactorily, concentrate onthat for future study, and destroy the rest? Doing this over and over might result in domesticated bacteria (so to speak) that are an improvement over the natural strain,at least from our own selfish viewpoint, as is true of cattle, horses, sheep, and swine.We can indeed do this, but we have learned even better techniques.The genes of all organisms, including bacteria, are made up of molecules of "deoxyribonucleic acid," usually abbreviated DNA.The DNA in any cell guides theformation of enzymes that, in turn, dictate the kind of chemical abilities the cell has
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