The Rise and Fall of Humanity

20TH CENTURY REFLECTIONS The 1969 Alumni College Lectures — III Too many people and too much demand on the supporting capacity of the earth have thrown our ecosystem intolerably out of balance. How much individual freedom must we give up? Do we want to? Is there time?

SYDNEY E. JUNKINS PROFESSOR OF BIOLOGY

EVERY PROSPECT PLEASES

I propose to develop a biologist's perspective of Man, a survey of the circumstances that brought him to being, the situation in which he now stands, and the prospect for his future. I should say at once that what I see is frightening and almost hopeless, and that anyone who wants the happier verdict of other biologists should go to the now rather dated work of LeCompte du Noüy, Teilhard de Chardin, or Sinnott.1 None of these mystics was much impressed with the triumph of human ignorance and evil in our time. I incline to the more gloomy figure of Alan Gregg, who in a famous address before the American Association for the Advancement of Science in 1955 suggested that "the world has cancer, and the cancer cell is Man."2

But let us first praise famous machinery. This is the age of fabulous engines that run themselves and accomplish their own built-in purposes. Perhaps it will have been the last great accomplishment of Man before he became extinct (like God before him) that he made machines in his own image but lacking in his own wisdom. Machines have been designed that will play you at chess, study the particular weaknesses of your own game, and beat you at it. You can hire engineers to build you a machine that will look at the great tapestry above the altar in Coventry Cathedral and weave another like it; or a machine that will compose a sonata in the style of Mozart; or translate into English a Russian paper on the superconductivity of liquid helium.

Lately we bought for an advertised price of $24 billion a machine that went to the moon, left some monitoring apparatus and trash there, and brought back some sand and gravel. It also took men to the moon, but that was for military and political reasons and for the national vanity. Many of the decisions required during the operation were being computed in Houston, and apparently all of them could have been, at much less expense, without taking the men along. But it gave us all a real lift - forgetting alternative needs for the $24 billion —to be on the first team to get there, to prove it possible.

But now new problems arise. The space effort has acquired a momentum of its own. How are we to stop it from bleeding us to death? One suggestion has been to shift goals. We should now be the first to build an apparatus for this kind of money that would serve a non-military and economically useful purpose, like harvesting the oceans. To make it even more sporting and novel, why not throw in the extra requirement that this machine should contain the instructions for keeping itself in repair, finding its own energy and materials, and reproducing itself periodically? It has been seriously argued that such a project is technically feasible. When we Americans set ourselves a goal of this sort, things begin to happen.

One can, admittedly, foresee the difficulty that the multiplying units would overpopulate the oceans unless we killed off and disposed of the old ones as they brought their harvests to port. Even so, the ocean's resources would eventually approach exhaustion and we would have to seek out and exterminate the last of our mechanical whales. Having succeeded in this, we would again find ourselves stuck with a non-expanding economy or worse. What then?

It would be a still greater accomplishment, a new American first, a new much-needed distraction and entertainment, to design a purpose-serving machine that would work for us, fuel and repair and reproduce itself, and in addition adapt to the alterations it made in the earth. This would mean that we would have to build into it not only the self-reproducing computer program by which it constructs and operates itself but also directions for develop- ing new structure and behavior when necessary, so that it would never wipe out its resource base or find itself blocked by intolerable changes in its environment. It would be its own Houston, embodying the wit to serve its purpose forever, never toppling into a grave of its own digging, always sensing the main chance, always winning the chess game.

But I am confident we are not going to go waltzing down that path. However challenging the problems of design, however rich the payoff or fallout, there are two large defects in the scheme. The first is that, like a gaggle of Go-lems, the machine and its progeny might get out of hand and start using human beings for raw material and energy. Not that we as a people are so conservative, so lacking in the adventurous spirit, as to back off from such a risk. See how we are setting an even more gruesome trap for ourselves in the atomic missile race. No, the reason why we are not going to create the first purposeful, independent, self-reproducing, non-deteriorating, trap-avoiding, adaptive machine is that it's been done already. And not by Americans either. It started itself up perhaps four billion years ago, dedicated to a single purpose. It has been redesigning itself ever since, for greater and greater efficiency in pursuit of the same goal. It is well established and will not tolerate competition from anybody, even Americans. We'd better get to know it.

THE LIFE MACHINE

Familiar as we all are with some parts of this enormous purposeful engine, we have the same difficulty in recognizing it as a mackerel has in discovering salt water. Persistent through eons, the life machine at any point in time consists of all the plants, all the animals, and all the microorganisms then alive. We see these mostly as individuals and define them in resemblance groups as species, failing to see the aggregate of all of them as a single machine. No individual, and no species, can perform the function of the Life Machine. Each species, through all its own individuals, can only make a minor contribution to the working out of the grand strategy, and in the interest of this, it will eventually die and be discarded, just as its individuals die. Only the whole Life Machine is eternal.

The purpose of the Life Machine is to pull together as much as possible of the material and the energy at the surface of the earth, and convert it into the substance of living things. The purpose of life, to create more life, is programmed into every living plant, animal and microorganism, and all these are working with and against each other to serve the grand strategy. All the millions of species, and all their billions of individuals are merely expendable parts, through which the Life Machine works.

A woolen blanket serves a function toward which no one of its threads is essential, and none of the fibers in any single thread is essential. The blanket succeeds nevertheless, and would last forever if the perishable fibers knew enough to replace themselves before their time was out. In some such relationships, the enormously redundant species and individuals form a perennially self-renewing blanket of life over the earth.

HOW IT AROSE

In order to come closer to the sense-making fabric of the Life Machine, let me present a fanciful history of how it invented and perfected itself. This will not be a digression from my main intention to take a look at where Man stands today, but serves rather to set the principal point and the vanishing point for the biologist's perspective. I call it a history but it is really only a list of things which certainly did happen, probably arranged in the wrong order, most of the dates conjectural. Mediate and immediate causes are thrown in from the imagination, to give artistic verisimilitude, like the corroborative detail of Pooh-Bah. The important point is that what surely did happen has left its print in us and around us, and contains our destiny.

Since you are a student again, taking notes, please start by drawing a large circle and mark it off as a 24-hour clock face, with hours 0 and 24 at the top and 12 at the bottom. One sweep of the hour hand around this clock will represent four billion years of earth history, ending at the present. Three billion years ago is at 6 o'clock, halfway down the right side. No better reasons can be offered for picking the stretch of four billion years than that most of what concerns us here must have occurred within that time, and it is an easy clock face to draw.

At zero hour, it is not known whether the water at the earth's surface was behaving like snow or rain or steam, but there was probably no significant amount of free oxygen in the air, and hence no ozone to screen out the sun's ultraviolet light. Undoubtedly there was a lot of carbon dioxide, ammonia and methane blowing around. Laboratory experiments show that these gases, given aseptic conditions and large amounts of heat and other energy sources, will interact over weeks and months, producing a great variety of organic compounds, of increasing complexity. One may guess therefore that in the first billion years of our clock, a fairly thick soup of miscellaneous organic material could have accumulated, particularly in the muddy estuaries of the oceans.4 This is impossible today because practically all the methane and ammonia has been reallocated, oxygen is widely available, and living microorganisms lie everywhere in wait to use up such accumulated materials for food.

But the world was then aseptic, without life, preparing for life to invent itself. During part of the next billion years (before 12 o'clock on your chart) myriads of these diverse organic molecules must have become locally concentrated in films or lumps, and some mixtures of them must have found themselves capable of forming biological membranes. It is with these complexly layered membranes that modern cells protect their special contents, and take in and give out materials selectively, and release and capture energy through big-wheel and little-wheel molecular chain-reactions. The protocells must also have learned how to regulate their structure and perform syntheses from selected materials and control their energy conversions by means of other highly specialized molecules such as we find despatched and marshalled in modern cells through information-containing polymers like DNA and RNA.

LeCompte du Noüy's mathematical proof that this could never have happened by chance was one of the most primitive errors in logic ever committed by a biologist. There was plenty of room, plenty of time, for more and more intricate and successful combinations of these molecular mosaics to occur by chance. Nevertheless, even the most primitive microorganisms remaining today give little hint as to how the finally successful patterns actually evolved. The electron microscope shows us a previously undreamed complexity of "ultrastructures" within cells, sometimes arranged in strict geometric stacks, sometimes stirred up at random, often changing in size, shape and position by the hour: mitochondria, chloroplasts, ribosomes, chromosomes and other mitotic apparatus, and yards and yards of biological membranes of more generalized sorts, around the cell surface, on the nuclear surface, and amongst less well ordered constellations of tiny things that suggest dust, sand, gravel, and balloons.

Perhaps some of these categories of cell organelles first arose separately and became combined accidentally. In that case, no doubt, certain combinations were more efficient in carrying out the life function, and prospered at the expense of other less efficient ones, and this continued until the earlier experimental models were starved out by competition and disappeared. Most modern cells show most of these organelles, all rolled into one package, all inherited from the parent cell, self-replicating, and under central control of the inherited computer-program in the nucleus.

No one who has studied the complexity of a modern cell, or read any of the biochemistry and biophysics of how it survives, grows, and reproduces itself, can doubt that most of the first two billion years of evolution must have been needed for the Life Machine to build itself up to the cell stage. During this time the protocells could have been feeding upon the accumulated soup of organic material in the oceans. As more and more living substance was formed this resource would be used faster than it was formed and would disappear at an increasing rate, until it became uneconomical to gather.

There had to be an escape from this dilemma if the Life Machine were to survive. One strategy would have been for certain protocells to learn how to devour others which were still making a living off the soup. If the Life Machine had merely taken this direction it would have polished itself off in short order like the Kilkenny cats. As another escape, the protocells could have discovered how to live off simpler and more abundant sources of material and energy - like water and carbon dioxide and sunlight - thus becoming the first plants. But if the Life Machine had taken this direction only, it would have come to an end as soon as the least common of the essential components, probably carbon dioxide, had been tied up in more complex living substance. Neither cell-eaters nor plants can escape eventual starvation in a closed environment unless the source of what they need can be continually renewed.

Faced with the impossibility of proceeding along either one of these lines, the Life Machine found success by moving in both directions at once, thus inventing the selfcycling ecosystem. In a given area containing adequate energy and inorganic materials, the new photosynthetic plants used the carbon dioxide, nitrogen and water to grow on, giving off oxygen in the process. At the same time the cell-eaters used the oxygen and the plant materials to grow on,thus releasing carbon dioxide, nitrogen and water for re-use by other plants. (In early millennia the plants had not released enough free oxygen for the needs of the cell-eaters, but metabolic paths are available that do not requirean input of free oxygen. These are used by the sulfur bacteria and other anaerobic microorganisms which still abound in our lake bottoms, mudflats and septic tanks, where they escape the competition of the more modern oxygen users.)

The result of the balance was that both the autotrophs (plants) and the heterotrophs (cell-eaters) won reprieve. But there was a price: the success of each had to be limited by, as wellas being fostered by, the success of the other. Only by combining their efforts and making them dependent on each other could the Life Machine become eternal and increasingly efficient in achieving its purpose.

At some stage or other, the cell-eaters differentiated into (1) animals, which were selectively favored by their improvementin mobility, anatomic and physiologic specialization, and quickness in sensing and adapting to momentary changes in the environment, and (2) decomposers (bacteria, fungi, etc.) which remained structurally simple and became scattered lavishly but at random by riding the winds and the waters. They specialized themselves for breaking down the tissues of plants, animals and other decomposers, making the materials available for more plants.

It is not known when this fundamental tripartite division of life styles took place. Farther back than half a billion years, the fossil record becomes increasingly difficult to read, bufairly convincing traces of plant cells (algae) have been found in rocks two billion or so years old, and very old traces attributable to bacteria are also known. This requires a notation at 12 o'clock on your 24-hour clock face.The self-renewing ecosystem is probably that old.

While the Life Machine was inventing itself and becoming eternal, it must also have invented Death. Or was it merely faced with something already fixed in the physical scheme of things, like gravity, or boiling and freezing points, or the chemistry of carbon? There is a mystery here. The death of a soft semi-living scum or blob, or of an actual living cell, through digestion or incineration or physical disintegration, has happened from the beginning and is easy to understand. But to escape such a fate merely postpones a "natural death" that follows a period of senescence. This happens to every living thing, except to certain microorganisms which are somehow rejuvenated as a byproduct of their reproductive process. Es ist der alteBund, Mensch du musst sterben. Whence this ancient law? There is a science of geriatrics, and there are numerous hypotheses, but the necessity of death is still a mystery. Perhaps there are so many sufficient causes of natural death that there can be no logical proof for the necessity of any.

But it seems clear that if the Life Machine had ever produced one single individual, whether plant, animal or decomposer, which was immune to the law of senescence and death, that individual would have produced a species that could stop the show throughout its own range. It would have served as a trap for materials and energies, preventing the recycling which was needed for the support of the whole community. If this could happen once, it could happen again and again, so that eventually every spot on the globe would be occupied by one or more non-senescent species. Sooner or later then, certain crucial materials would stop recycling, and each of the species would then die out not from senescence but from one form or another of starvation. It is a sobering thought, that the Life Machine can be eternal only if all its subsidiary living units will accept death.

There is a corollary mystery. Our rate of living and our rate of growing old is fastest when we are quite young. The children remind us often enough these days that we are in an advanced state of senescence when we reach maturity. How does a parent pass on life but not his own level of senescence to his offspring? If the solution to this dilemma had not been found, the Life Machine itself would have grown old and died a natural death.

Having worked its compromises with death, having perfected the art of making and reproducing cells, having achieved the balanced and recycling community of producing, consuming and decomposing species, the Life Machine was ready for the long process of spreading itself into all corners of the earth the more to fulfill its purpose.

And now, oddly enough, its trump card was a slight degree of imperfection in the reproductive process. The goal was to build living material out of the resources of all conceivably tolerable environments. The requirements for adapting itself simultaneously to the ocean abyss, arctic seas, hot tropical estuaries, fresh water, wet land, temperate soil, and desert stood as challenges. Established in any one such area, it would find itself further tested by fluctuating conditions during the passage of millennia. Huge unidirectional changes also took place remorselessly in the composition of the atmosphere, in the salinity of the oceans, in available radiant energy and mineral resources. But living species as we know them in our short lifetime are severely limited in their choice of habitat. Robins cannot swap territories with chimney swifts, nor mackerel with perch, clams with tapeworms, water lilies with wheat. To occupy all the possible niches and to hold them while the conditions change, the Life Machine needs an abundant reserve of slowly adaptable species, all pushed by competition to make the maximum use of their adaptability.

Fortunately for the whole machine and for any species, none of the individuals ever reproduces itself exactly, but always with minor variations, mutations in transmitted genes. I need not review why this is so, nor how it is that the forces of natural selection use these billions of variations to shape new species and to adapt new and old species to different environmental situations. But without the accidental mutations the Life Machine would never have been able to cover the planet with a continuous and permanent blanket.

One of the great inventions—perhaps not as crucial as death but one cannot be sure—was sex. This may have had its beginnings before the completion of the first modern cells more than two billion years ago. Even bacteria and protozoa have sex nowadays. There is a tendency to think sex had to be invented to put a little jazz into the otherwise dull desperation of an individual's life, but it is difficult to think of liverworts, angleworms, pine trees, seaweeds, jelly fish, and cabbages as taking any note of their highly developed sexuality, let alone getting any fun out of it.

The essential contribution of sex to a given species is to multiply enormously its inheritable variability by bringing together in each individual a new unique combination of gene mutations and permutations. In a species with asexual reproduction ten generations of inheritance will bring to the latest scion the new mutations that arose in ten previous individuals. With sex, the same stretch of lineage might bring him a combination of new mutations that had arisen in more than a thousand (210) ancestors, and the roll of the dice gives him a different combination than that of any of his cousins. Sex has thus provided rich material for field testing as to which organisms can survive where, and has speeded up the effort of the Life Machine in pursuing its goal in all parts of the planet's surface.

Let us move along toward 18 hours on your clock face, a billion years ago. I am still listing things that did happen, though when and in what order they happened will never be known. The next great step was probably taken independently many times over. Cells multiplying from the same parent found that they could stick together in groups and take on different individual characters depending on whether they were on the surface or in the interior of the mass, and whether or not they were in contact with particular kinds of substrata. Such specializations led to the differentiation of tissues and organs, and to the advantages of division of labor within the group. One supposes that multicellular aggregates could have existed in huge numbers, forming and disbanding as yeast cells still do. It was an important new step when embryonic development from fertilized eggs began to be standardized, for then natural selection could begin to work on reproductible patterns of cells.

We are only gradually coming to realize what a formidable accomplishment it was to invent a controlled and purposeful embryonic development. To the intricate instructions encoded in the inherited DNA molecules of every cell, covering the business of survival and reproduction, there had to be added the basic instructions to achieve every kind of cellular differentiation anywhere at any stage in the life of the multicellular organization. And since any one cell could only end up along one .of these tracks of differentiation, all of them had to be instructed to distinguish any one of a host of particular circumstances in which they might find themselves at some particular stage of development, and only then to put into operation the instructions for specializing in an appropriate way, keeping all other instructions under lock and key.

For example, a single carrot cell can multiply itself into a carrot plant. It must proliferate some cells with root hairs, others with chlorophyll, or orange pigment, or qualified to take part in any of the tissues of the new plant. But the signals to do any of these things must control the behavior of only particular cells at particular appropriate places and times, or the product is not a carrot plant but a completely misbegotten tumor of carrot cells.

There are neural crest cells migrating out of the brain of a three-day-old frog embryo that can form cartilage or bone or pigment or nerve cells or connective tissue cells or glands or teeth in the next few days, and it is the part of the head that they find themselves in which tells them which of their many types of inherited instructions to follow. A few days earlier, cells of this same lineage could have demonstrated under other circumstances that they were capable of becoming blood or muscle or kidney or brain or eye cells. One finds in modern embryos a master plan, a strategy and tactics, that brings out the proper response in each multiplied cell. This has been added in coded form to the program inherited by the fertilized egg.

To develop such a program for embryonic development must have been a greater leap forward than transforming a ten-cent rocket into a moon-visiting machine. But the modern phyla of multicellular plants and animals and decomposers differ so much in their embryonic development that one can guess the Life Machine made the leap on a number of occasions. The question cannot be resolved by the fossil record.

The clouds obscuring the history of the Life Machine suddenly begin to break at 21 hours on your clock face, around half a billion years ago. Rather suddenly, in rocks of the Cambrian systems, appear fossils that can be assigned to most of the major phyla of invertebrate animals. The very range of these fossils, and the fact that even earlier rocks are slowly yielding evidence of worm trails and almost-legible patterned imprints of organic remains, make it clear that a great deal of evolution of lesser phyla of multicellular organisms had already taken place.

Since then, events have marched more rapidly, at least as you watch the pointer sweep around your 24-hour clock. By half past 22, between 250 and 125 million years ago, modern bony fishes had become numerous in the oceans, displacing most of the aggressive sea scorpions and jawless fishes, and there were many animals established on land. Probably the plants, including now many extensive forests, had brought the oxygen content of the atmosphere well up toward the 20% that most of us are lucky enough to breathe today. In fact a good deal of the woody product of that luxuriant land and swamp vegetation was packed into our present-day coal deposits. Bony fishes were old hat, the age of reptiles had begun.

Eighty million years ago the mammalian body plan was being perfected out of less successful reptilian stocks. About 70 million years ago the first primates arose, in the form of squirrel-shaped lemurs. That was about 23 hours 35 minutes on your clock. The earliest known apes showed up in the Oligocene of Africa between 35 and 25 million years ago (23 hours 48 minutes). Apes beginning to resemble man are known from 5 to 15 million years back, but the transition to primitive men (Homo Erectus and finally Homo Sapiens) took place well this side of three million years ago. As we have drawn our 24-hour clock, the time of modern man lies within the last minute. One second represents 45,000 years. The 5000 years of written history is one ninth of one second.

It is not to be assumed that the Life Machine had been using all that time before the appearance of man for the purpose of setting the stage for human life. That is not its purpose; it is not that kind of a machine. In fact, nearly every modern species, of plants, animals or decomposers, is as recent or nearly as recent as man, for species wear out and are replaced after only a few million years. All of us together are a kaleidoscopic mix of temporary agents for filling niches in the biosphere, maintained in balance and in sensitive response to changing conditions, in order to maximize the amount of living substance that can be supported on the planet. In terms of the overall life purpose, no single species is of great importance, even in its own allotted time span. Constant adaptation to changing conditions within a precariously balanced ecosystem is the price of survival for any species. Elaborate mechanisms wait to bring to heel any species that upsets the balance or takes more than its share. As for individuals, their only essential purpose is to provide for the persistence and adapt- ability of the species. Just because many of them will fail in this task, plenty of them are provided. The Life Machine does not count its fallen sparrows. Mindful of its purpose, it just uses them over again.

THE CLIMB OF THE ROCKET

In the Western world we have been telling each other for more than two thousand years that Man is an especially favored species, the lord of creation, ordered to multiply and inherit the earth. All the same, we know that many prosperous civilizations have disappeared before and during our era, sometimes mysteriously, but sometimes due to their adoption of methods of exploiting their ecosystem that destroyed its balance.

How are we doing? I could divide the history of modern man into the pre-cancerous and the cancerous phases in the figure of Alan Gregg. Or in a prettier way I could distinguish between the climb of the human rocket and the all-too-brief moment when it blows the sky full of colored stars, and drifts away as ashes. The boundary between these two phases lies somewhere within a generation of A.D. 1870, the way I see it. On your clock, that was 2.15 thousandths of a second ago. For the moment the sky is lovely.

What happened wasn't all "our" fault. Even the modern monkeys, baboons and apes have an elaborate social organization with establishment and discipline. Australopithecus apparently had tools, Homo Erectus used fire, and weapons were among the earliest inventions. There is no way to find out when, in the transition to human beings, a spoken language began to develop. Beginning then, acquired experience could be passed along, skills could be taught, divisions of labor could be worked out, and humane qualities could start accumulating. Anthropologists have brought us objective evidence of well-established cultures of Homo Sapiens in scattered centers from as long ago as seven thousand years. Agriculture, fixed communities, irrigation, smelting, and the application of wind and water power soon followed. The rocket had started to rise.

It is impressive how old the earliest traces of the spiritual life are. By contrast, improvement of the technique of learning came late and came slowly. Perhaps this was because it depends on the very last phase of the development of the human intellect, the ability for formal thinking, which never appears until late childhood, and sometimes hardly at all.5

The first great steps in learning how to learn are documented in Greek cultural history, with the development of schools, libraries, mathematical and other logics and the evolution of a vocabulary rich enough for generalization and abstraction. Various schools of Greek philosophers developed models of the universe, with internally consistent explanations of how things behave, but the schools were intolerant of each other, and no one philosophy was ever put to experimental test.

The goal of a single unified and experimentally verified system of thought about the physical and biological things of the world was not conceived until the Renaissance, when the "new philosophy" - science as we know it - emerged from the intercommunications between local learned societies. It was these few people who set us on a course of systematic exploration and exploitation of nature, in a selfcorrecting internationally cooperative search for understanding and control.

The development of science gave a powerful boost to the rocket and touched off an exhilarating era of hope and confidence. Invention became a fashionable art, and effort that had gone into cathedral building was poured into technology. The industrial revolution brought material pros- perity to the establishment. Public health measures, decreasing the ravages of disease, turned upward the curve of population growth. Even today, as a carryover from the Enlightenment, the belief lingers that technology, the gift of science, will keep us going. But technology, born of rational thought, soon escaped from rational control.

One of the principal novelties of the industrial revolution was the harnessing of new physical sources of energy to run the machines. The earliest factories were at waterpower sites. The invention of steam engines allowed factories to be located anywhere and to be run in times of flood or drought. Techniques for the control, generation and transmission of electricity, and the perfection of the internal combustion engine, each in turn added to the amount and versatility of the application of non-human, non-animal energy to production. A fateful turn occurred when we began to use coal, and then oil and natural gas, not only for warmth and cooking but also for manufacturing, for generation of electricity, and for production of food.

This exploitation of the fossil fuels on a gigantic scale was a biologically unprecedented example of a species deliberately stepping out of its ecosystem into a new self-created one. It was a bolder step than the invention of agriculture itself. Until this time, the size and productivity of the cities were held in check because food production required most of the population to work on - the land. Food was the limiting factor and Malthus was right: the only escape for the masses from starvation and misery was through limitation of births.

The last few generations have seen a drastic change. With fossil fuel for energy, factories have produced food-producing machinery and fertilizers, coal- and oil-burning engines have transported materials to the farms, tilled and harvested the crops, and processed and delivered the food, feed, and fiber.

In our affluent part of the world, productivity per man has enormously expanded, the rural population has declined to a new unprecedented low in each succeeding decade, cities have multiplied in size and number, and food has never been so plentiful. During this part of the climb of the rocket, even well-informed people began to think Malthus had been wrong. But it needs to be remembered that the food for our present vastly increased population is now being bought with fossil fuel, a non-renewable resource.

The rocket rose swiftly, but each new advance brought larger problems. The collapse of empires through erosion of the fertile land, the salting up of irrigated basins, the silting up of harbors, showed thousands of years ago that new technology can yield rich profits for a time and still bring ruin in the end. The taste of comfort and prosperity taught men envy and led to the invention and hideous perfection of war. Long before bears and wolves became rare, it had become clear that man's last formidable enemy is man. He is the one species that preys upon its fellows, the one species that ruins its own resource base.

THE SEVEN HORSEMEN OF THE APOCALYPSE

They were all good, all superlatively clever steps: the development of language and of tools, the taming of fire, the cultivation of crops, the winning of freedom from the forces of natural selection, the establishment of science and technology, the building of machines and application of non-human power to them, the exploitation of fossil fuels to feed an expanding population. But now we know how badly we have fouled our nest, how much we are in danger of making the world uninhabitable for ourselves. A horrid picture from my childhood shows the four horsemen of the Apocalypse in the symbolic dress of famine, disease, war, and death. Modern apocalyptic writers need a larger number.

I thought of limiting myself to seven, a nice ominous number, but it pinches a little. Something has to be left out. I choose to avoid the possibility of atomic war because of its uniqueness, its finality. There is no peril so desperate, so oppressively near. None of the other disasters can happen totally this evening, or totally tomorrow. They can be seen coming. There is time, if not to turn them aside, at least to blunt their impact. Let us indulge ourselves and consider only these others.

1. Growth of the Human Population

The population growth rate is usually given as the number of births minus the number of deaths per year per thousand. It may be a positive number, a negative number, or zero. It is important to note that any given growth rate may be produced in a region with a very high birth rate or a very low one, depending on the death rate. Also, in predicting from current growth rates it is essential to examine the age structure of the population: the proportions of immature, presumably fertile, and post-mature individuals. A high growth rate is vastly more ominous in a population with 50% of its members under the age of fifteen than in one with relatively few children and old people. Demography has its intricacies.

In looking to the future, the principal matter for concern is the time required for a given population to double in numbers. This can be figured out from the growth rate by a compound interest formula, making what seem like reasonable assumptions about the age and sex distribution in the population, and future birth and death rates. Of course, all of these figures are actually subject to change. Here is a sample result of such calculations:

Growth Rate 0.5% per year 1.0 1.5 2.0 3.0 4.0

Doubling Time 139 years 70 47 35 23 18

These doubling times usually do not give accurate predictions beyond the first or second decade because of changing values of the factors in the calculation. For this reason the experts usually make high and low predictions on the basis of a reasonable range of the unpredictable variables.

Rates of growth in many parts of the world, and in previous centuries, are based on unreliable or incomplete estimates, so that serious discrepancies are readily found in the figures of different authorities. This is a minor point. They all point to the same sort of acceleration in human population growth today.6

From the year 1000 to 1650 the world population probably doubled. The next doubling, by 1825, took not 650 years but 175, and the next, by 1905, took only 80 years. World population is now assumed to be growing at the rate of 2% per year, with an expected doubling rate of 35 years. A child born today with life expectancy of 70 years might thus see world population increase from the present 3½ billion to about 15 billion unless something changes drastically. The growth rate in the United States has been gliding down for a few years, and headline writers have made false cheer from each new report. It hoVers now at 1% but students of our population structure expect it to go up again. President Nixon's way of dramatizing the prediction from this "low" figure was to say we would have to produce the equivalent of a new city the size of Dayton, Tulsa or Jersey City every 30 days for the next 30 years to accommodate the population expected in the year 2000.7

I shall make only two observations about the population explosion. The first is that it cannot go on indefinitely. A continued logarythmic growth of any sort eventually approaches infinity at an unimaginable speed. Luten calculates that the present world population, continuing to grow at 2%, would reach standing-room-only in about 800 years, i.e. one person per five square feet, land andsea. A 2% growth rate since the time of Christ would have given us a population twenty million times larger than what we now have, stacked up 100 people per square foot. Such a crush being obviously impossible, it follows that something must occur rather soon to rein in this terrible horseman. What happens could be hideous beyond comprehension (war, famine, plague...) or it could be a planned cooperative intelligent effort.

My other observation is that, in spite of the fact that the technology of birth control is already quite adequate to solve this problem, and faint signs of progress are in sight, we are not going to rescue ourselves in this sensible humane way. Even the Planned Parenthood groups, who are leaders in this almost hopeless effort, merely concentrate on preventing the conception of unwanted babies. The American problem and the worldwide problem is that parents want too many babies.

Kingsley Davis9 has pointed out that no country in the world has yet developed a population control policy, and that planned parenthood and the voluntary practice of contraception will have no significant effect on solving the problem. Bernard Berelson recently reviewed the policies that might work if they were adopted, but concluded that none of them is universally or even generally acceptable. Even if every community in the world became overnight dedicated to the goal of zero growth (an average of two children per family) there would continue to be a very large population growth well into the 21st century, because in the world today the adults of fertile age are greatly outnumbered by children.

Meanwhile, the 1969 United States budget for population problems was $116 million but we had earmarked 35 times that for space programs, and nearly 700 times that for military programs. And Nixon said, "Clearly, in no circumstances will the activities associated with our pursuit of this goal (population control) be allowed to infringe upon the religious convictions or personal wishes and freedom of any individual, nor will they be allowed to impair the absolute right of all individuals to have such matters of conscience respected by public authorities."

It is good, and indeed remarkable, that President Nixon has reached out a finger and pointed to our population problem, but the urgency of his concern disappears in his flatulent peroration: "If we now begin our work in an appropriate manner, and if we continue to devote a consid- erable amount of attention and energy to this problem, then mankind will be able to surmount this challenge as it has surmounted so many during the long march of civilization.... Let us act in such a way that those who come after us - even as they lift their eyes beyond earth's bounds - can do so with pride in the planet on which they live, with gratitude to those who lived 'on it in the past, and with continuing confidence in its future."

It is reasonable to suppose that if a hundred million people were expected to crowd in upon us in the next thirty years by parachute or border infiltration, our leaders would rally us with a different choice of words and a recommended program.

All the rest of the problems on my list arise because there are already toomany people, herded in the wrong places, asking too muchof the earth.

2. Famine

President Johnson once said, "Man's greatest problem is the fearful race between food and population. If we lose that race our hopes for the future will turn to ashes." Food production increases by simple interest, but the population increases by compound interest, as Malthus first observed. His "dismal theorem of economics" was that if the only deterrent to expansion of the population is starvation and misery, then the normal state of affairs will be a starved and miserable population. To this the economist Kenneth Boulding has added an "utterly dismal theorem," that the end result of any technological improvement will be to permit more people to reach the same state of misery and starvation.

The widespread shortage of food in the world today and the practical certainty that Mr. Johnson's fearful race cannot be won even to the extent of properly feeding the present world population or of preventing the situation from sharp deterioration in the near future have been many times documented. Recently, however, new genetic strains of wheat, rice and corn have been introduced in a number of hungry lands.The great jump in productivity, where multiple cropping can be practiced and sufficient water, fertilizer and heavy machinery can be furnished, has been widely hailed as a "green revolution."10 At the moment it seems a major technological achievement but the warnings are already outthat predictions based on it may be blasted in the next decade or two for a great variety of governmental, economic, sociological and biological reasons. Already one side effectis appearing: the rich are getting richer, the poor poorer. In just these lands, the populations are growing so as to double in 25 or 30 years. If the food supply does not continue to double in less than the same period, the net accomplishment will be utterly dismal.

This in fact is the thesis of the Paddock brothers.11 Their conclusion is that the United States must be prepared in the next century to decide in its own self-interest which are the starving countries that we should favor with our food surpluses, and which are so firmly caught in the Malthusian trap, or so relatively useless to us, that we should abandon them to the great famines that surely must come soon.

3. Exhaustion of Non-Renewable Resources

The non-renewable resources of fossil fuels and metals, and the very slowly renewable resource of agricultural soil, are being used up at rates which are quite well known, but for obvious reasons the dates when they will become inadequate cannot be calculated. All we know is that the earth cannot continueindefinitely to support the human species in the style towhich some of us have suddenly become accustomed.

On the average, each American now consumes as much of the world's resources as 25 to 30 residents of India. With 7 % of the world's population we are now absorbing more than 60% of the world's mineral production. Our own affluence is increasingly dependent on imports from other countries. Park12 estimates that if the rest of the world reached the level of affluence of the United States by the year 2000, the then doubled population would need to be processing 11 times as much copper per year, 12 times as much iron, 16 times as much lead. Plastic or other synthetic substitutes for metals are expensive in fossil fuels, which are also non-renewable.

It has been estimated that half the coal ever burned by man has been burned in the last 31 years, and half the oil in the last 16. Lamont Cole points out that modern agriculture, which raises more food on less land with fewer laborers, is not really a triumph of efficiency. It is essentially a device for exchanging the calories of fossil fuel for food calories. He reaches this conclusion by taking the calorie value of the food we produce and deducting from it the fossil fuel calories used by the farmer's machines, those used to build and deliver the machinery to him, and those to mine the necessary raw materials. Also those used to manufacture, process, transport and apply fertilizers and pesticides, to collect and deliver the water, and to process and distribute the food.

With vastly more effective prospecting methods, the rate of expansion of proved resources in fossil fuel, particularly oil, is still encouraging, but the demand for power is on a steep climb too. It is foolish to predict when we will run out of these resources, but to deny that the time will come is to deny that they are non-renewable. When that time comes, another and enormous source of energy must be available or the human species will have to drop back to the agriculture of the hoe and the horse, with primitive transportation and little reliance on chemical fertilizers and pesticides. Under these conditions the earth might still comfortably support a human population like that of the 1600's.

If this required the shrinkage of our numbers to an eighth of the present population, I would of course propose in town meeting that those whose names began with the first few letters of the alphabet be chosen to survive.

The rate of burning of fossil fuels is increasing very rapidly, and already we are releasing six billion tons or so of carbon dioxide per year into the atmosphere. Green plants decompose some of this, and the oceans can very slowly absorb it, but the CO2 level in the air is apparently increasing. This is being monitored with some concern, since it has been suggested that it interferes with the loss of earth heat to outer space. If so, it could produce a "greenhouse effect" that might eventually result in the melting of the polar ice caps and the flooding out of most of the large cities and inhabited lands of the earth. On the other hand we are polluting the atmosphere with dust and soot at an accelerating rate, which is reflecting sunlight away from the ground, and this may be pushing us to a new ice age. Which way will the balance tip? If neither way, will the living be better than now, or worse?

4. Atomic Energy

It is quite clear that we are damned if we don't develop new sources of energy before it becomes economically impossible to recover the last traces of fossil fuel, and the question is whether we are also damned if we do. At the moment, the prospects are not exactly bright that controlled fusion of hydrogen to helium will become possible. Even if this problem were solved tomorrow, no benefits would be likely to accrue before world population has doubled again. However, the age of power from atomic fission is beginning. There were a dozen or so such power plants running in this country in 1968 and scores more are under construction or contemplated. They are all designed to use uranium-235, which is in alarmingly short supply; therefore, they must promptly be replaced by breeder reactors, which are still only in experimental design but will surely be more dangerous. Only the very large atomic power plants are expected to produce kilowatts competitive in price with conventional generators, which makes it unlikely that they will solve the energy needs of impoverished nations or scattered populations. Also, since they produce electric power, which is applicable to only 20% or so of present American demands for energy, they cannot relieve much of our rising need for fossil fuels without an enormously expensive conversion of household and industrial equipment that is now run by steam or internal combustion engines. This in turn would greatly aggravate the shortage of metals.

But it is already painfully obvious that the reliance upon atomic fission for an energy source brings with it two dangerous and expensive problems. The first is the disposal of the radioactive waste. Fission bombs and fission power plants produce the same atomic by-products. One can disregard the ones that have half-lives of a few seconds or minutes, but others, including some that are very dangerously active in biological processes, have half-lives of hundreds or thousands of years. A rule of thumb is that they should all be kept under close control for at least twenty times their half-lives. For carbon-14 that would be well over a hundred thousand years.

All the control methods now in use are special ways of sweeping the stuff under the rug, whether it is set to cook in million-gallon steel and concrete tanks buried to their necks in some convenient desert, or embedded in glass or ceramic and stashed in old salt mines, or just quietly dropped into the ocean. The material has to be transported in trucks on our crowded highways. How much accidental contamination of the oceans, of the ground water, of the atmosphere, can the living world tolerate? The safety standards and monitoring systems are at present made by people at least obliquely involved in setting up new industries, not by experts solely charged with protecting the general welfare, and there is recurrent criticism of the standards as now defined.

The other problem is heat disposal. The generation of electricity in an atomic fission plant wastes very much more heat than in conventional steam generators, and nothing can be done with waste heat except to disperse it in the environment. It is not lost, it heats the world up a bit. The present concern is with thermal pollution of our rivers and lakes, since the cheap thing to do is to use water as a heat sink. There are engineering estimates that by 1980 from a sixth to a third of all this country's freshwater runoff will be needed as coolant for electric energy generators, and that by 2000 all of it will be needed. Biological estimates of the damage to the ecosystems of our estuaries, lakes and rivers are less than precise, but if the predicted trends are projected into the future they point to rapidly spreading and eventually total disaster. Cooling towers to disperse the heat in the atmosphere or subsoil piping to disperse it under farm land that could then be cropped an extra time or two per year have been suggested, but are more expensive. All of them heat up the world a bit. Recent calculations projecting current rates of increase in power demand, with current rates of heat wastage, have produced the dizzying conclusion that the world climate will be too hot to support human life in less than 150 years, even allowing for the delay in melting the polar ice caps.13

No city in the world is free now from the health hazard of smog. There is a growing list of instances of multiple deaths from smog corked up in a valley or a city by thermal inversions of the atmosphere. The major sources of airborne poisons are already known, and technology for reducing them is rapidly developing. A good deal of the sulfur in the air comes from fossil fuels. As sulfur dioxide it kills lung cells. Brought down as sulfuric acid in raindrops it dissolves buildings. Much of the carbon monoxide and nearly all of the lead comes from automobile exhaust, which also gives us many of the hydrocarbons and nitrogen oxides that rot rubber and ruin nylon stockings. But then there are also the scattered fine particles from the smokestack plumes of factories, mills, incinerators, and heating plants, coming back down upon us as sootfall and afflicting us with irritability in our productive years and emphysema in later life.

Theoretically, as we all know, this problem can be solved. But the prevailing winds bring one city's smog down upon others, and there are days when even Vermont knows it is down wind from Chicago and Detroit. In fact, the problem cannot be solved locally, or even nationally.

Meanwhile, more and more of the population is concentrating in the cities where the problem is worst. We double and redouble the sums we spend to keep the air from being soiled and poisoned, and those in charge of the work tell us we are losing ground. The ones who look farthest into the future are beginning to ask, among other pertinent questions, how much longer can we tolerate the internal combustion engine?

6. Water Pollution, Water Shortage

Most of our other troubles, whether solved or not, generate water troubles. The most intimate and obvious problem is pollution from raw sewage and industrial wastes. If we can give ourselves a merely passing grade in the matter of protecting ourselves from our own sewage, we do far less well with the comparable tonnage of excreta from our concentrations of farm animals. The food processing industries also turn out sewage in a tonnage not much less than what people produce. Oxygen-demanding dispersed organic waste has altered, or ruined, the original ecology of more brooks, rivers, ponds, and lakes than even most active conservationists know, since we keep no records on most of these resources. When the warning comes through the nose, it is usually too late.

Much more subtle are the problems of enrichment of the streams and ponds with the molecular and ionic materials that are still present in processed sewage and foster the growth of algae and other microscopic life. Half the enmes richment cofrom fertilizer run-off rather than from raw sewage.The switch from soaps to detergents has extended the pollution with phosphates. All this encourages a population explosion among the microorganisms whose support would normally be limited by the recycling of materials already present in the ecosystem. The visible effect of the enrichment is an alga "bloom" just below the surface of the water. The billions of algae, dying when their time comes, sink and disintegrate, exhausting the oxygen in the deeper waters, suffocating fish and ordinary plankton, leaving only stinking mats and floating wads of nameless and unlovely organic material. This is the way Lake Erie was "killed" - though Lake Erie is far from dead. The Life Machine has simply moved new species in, and the new ecosystems being developed there are useless and repulsive to us, though highly productive of living material.

Most of the fresh waters of the settled parts of the world are in serious trouble, from gasoline and oil pollution and over-enrichment and poisoning. It is the same from Lake Champlain to Lake Tahoe. The long-lived pesticides have not only produced mammoth fish-kills in the Mississippi and the Rhine, but also thousands of smaller ones, less well publicized.

The actual shortage of usable fresh water is still a novelty to eastern Americans, but the trouble zones are spreadater ing. Ground wis a reserve accumulated during Pleistocene times. First tapped, it seems free and inexhaustible, but used at a rate in excess of the annual input from rain and seepage, it becomes increasingly expensive and hard to get, until finally fewer people can live off it. To supply a periodically doubling population of individuals, each requiring more hundreds of thousands of gallons of water per year, at some point becomes impossible. Leading toward that distant time will be a long history of regional squabbles crossing state and national lines, leaping mountain ranges and river basins, about who has the right to what water sources. The water troubles in our southwestern states are nothing compared with those along the Jordan, the Nile, the Indus.14

7. Runaway Technology

This may be a riderless horse. We have no technology for reining in technology. It has been the western way of life to exploit natural resources by the newest and cheapest methods so as to maximize private profit. Hidden costs are passed on to the public at some later date and by the time we become aware of the size of the mess to be cleaned up the harm has been done.

The conservation movement was born of the shock of this realization. Nobody reckoned who would pay for the houses and streets in towns built over coal mines when the mines were abandoned and started to collapse or burn. No plans were made to restore to usefulness the land covered by the tailings of strip mines, or left to erode after the virgin forests were skinned off. No one thought what would have to be done by whom when the lakes became cesspools. We knew why we went all out with DDT, and perhaps we can deliver ourselves from serious damage by it to ourselves, but some of its destruction can never be repaired. We learned new ways to make paper more cheaply, at the cost of ruining rivers, which now need to be salvaged.

We developed machinery that made profits for the plantation owners but forced their tenants into misery and exile in the cities, leaving the costs to be picked up by quite other, quite surprised, quite unwilling people. There was nothing fundamentally wrong with our railroads, but somebody offered us private automobiles and now we have to travel more dangerously and inconveniently on highways that pave over some of our best farmland and violate our parks and sanctuaries. It began to look as though some of our uniquely beautiful valleys were being dammed and flooded out by silt-catching basins for no better reason than that we had set up a bureaucracy that knew how, and had to keep busy. What other reason than the military one is there for building monster jet planes that will take a few people across oceans faster than they need to go, shattering the nerves of vastly more people with sonic booms?

The military one. We hire R&D technicians to invent and build weapons that then produce undesired but predictable responses in other countries, thus determining our defense strategy and our foreign policy for us. More clearly than anything else, the atomic missiles race shows that we are in the grip of forces that have a self-generating momentum beyond the control even of our statesmen. And where can we honestly put the blame? The horse has no rider.

8. Plague

I tried to limit my horsemen to seven, but it won't do. We think we have freed ourselves from natural selection, from the old-fashioned biological balancing and reorienting forces, and so we have for the time being. We have exterminated the sabertooth and the cave bear, we can remain discreetly out of reach of the remaining wolves and grizzlies and tigers, and with reasonable precautions we can be free of tapeworms, liver flukes, and ringworms. But waiting in the background are the microbial and viral diseases, many of them transmitted by polluted water, or by contact in crowds, or carried by insects only temporarily held in check. If population growth is not arrested almost at once, if the predicted century of great famines is not averted, if the worldwide deterioration of the environment is not arrested, if our slap-happy tendency to put our big money and our great technology at the service of wrong causes is not corrected, then the world is surely approaching a time of political instability, social disorganization, and economic breakdown vastly more serious than any yet known. The last pandemic of the bubonic plague occurred in a time of peace and reasonable prosperity within this century, and it killed 14 million people. It is now established as an endemic in all the continents and lurks ready to strike again. The same is true of most of the great killing diseases. What an epidemic of smallpox could sweep through the world if our guard went down in major areas for ten years! Total chaos, developing in the overpopulated, impoverished, famine-swept countries, will undoubtedly spawn epidemics of a size and intensity never before seen. What kind of frontier defenses will be adequate?

If the last world war was a time for re-reading Thucydides, we should begin re-reading accounts of the great plagues of the Middle Ages. The mildest comment is that those times brought out the best and the worst in humanity. Even if we don't get atomized first, there are frightful times ahead.

WHAT WENT WRONG?

There are two facets to this unprecedented crisis for the human species, and they are cause and effect: too many people, and too much demand on the supporting capacity of the earth. Here, a moderately large population at a high level of affluence, there a swarming mass of human beings in abject poverty. In both cases, our ecosystem is intolerably out of balance. Why did this have to happen? A disturbing essay by Lynn White15 suggests that human individuals have been led astray by inculcation in an ancient Judeo-Christian point of view, that they are commanded to increase and assert their mastery over nature. I think the trouble lies farther back, in a direction taken by the stock of mammals many millions of years ago. To develop this idea I must return to the role of species and of individuals in the Life Machine.

To maximize the amount of life that can be supported in a given ecosystem, a large number of species of plants, animals and decomposers are brought into balance, each occupying its own niche and following its own instructions to make the best of the things available to it while contributing to the flow of energy and the recycling of materials. If one species in the ecosystem gets out of balance the whole community develops an instability that may either result in an irreversible change in its character, or in the control or rejection of the destabilizing element.

The human species has been manipulating its environment since the invention of agriculture, favoring the plants and animals that serve it for food, repressing or even exterminating others. Where this was overdone - e.g., Mesopotamia, the Near East, Yucatan - ghost cities and records of dead cultures remain to show how powerfully nature can strike back. Quite recently we have begun to use the treasure trove of fossil fuels to grow the food to satisfy the multiplying demands of our own population, and we congratulate ourselves on having temporarily freed ourselves from the normal restrictions of the natural world. It is a dangerous game we are playing.

No good asking why the human species takes these risks. A species is an invention of the mind, a generalization. Only human individuals actually walk and breathe and make decisions and it is the collection of individuals who have been doing what I say the species has been doing. What went wrong with human individuals, that they have gotten their species and their environment into such a mess? The other face of this question is, what is an individual supposed to be doing, and within what limits is he supposed to be held?

The Primary Computer. To simplify, I shall restrict the latter question to animals rather than plants or decomposers. I shall pick animals that are not on a rampage, animals that have (so far as we can tell) no conscious reasoning ability, no thoughts, loyalties, hopes or faiths. Some kind of earthworm or some frog will do. I assume that whatever one of these animals does, any choice that it makes, is determined by its inherited computer system. It receives from its ancestors a scanning mechanism which reports what all the circumstances around and inside it are at the moment. This information is checked against an inherited memory encoded in its central nervous system. The computer then not only orders up the strategy and tactics that had met that sort of situation successfully before, but directs what every cell, what every organ, what the whole earthworm or frog must be doing to contribute to that response. (Directions for unsuccessful responses are not encoded in this primary computer, because they simply are not inherited.)

To see what this genetic computer requires the individual worm or frog to do, let us follow his life history, watching him obey and reconstructing from what he does the nature of the commands.

1. As a member of a bisexual species he (or she) starts as a fertilized egg, a single diploid individual with unique heterozygous genie individuality. First, he develops. Since the fertilized egg is insulated to a degree from the outside world, his computer works at first mostly on internal information. It refers to the inherited memory in the chromosomes and brings out instructions of various intricate sorts to the ultrastructures of the cell, programmed so that the cell divides into two, then four, then eight cells ... until the word gets back to the multiplied computers in the multiplied cells that it is time to activate their inherited instructions for differentiation. Tissues and organs are formed, in such sorts and such patterns as have enabled the species to survive so far. The new individual acquires the sensory and neural apparatus for bringing in more and more information from the outside, and this is referred to the more and more specialized computer developing out of the inherited instructions, in a central nervous system (in the case of the frog a brain and spinal cord). He begins to move about, respire, feed, excrete, defend himself, in directions and at rates calculated to be appropriate to the sensed state of affairs from moment to moment. This is quite a trick for a self-built computer to bring off, and as an embryologist I wish I understood more of how it is done.

2. The young earthworm or pollywog, having broken loose from its protective envelopes and used up its dowry of yolk, is next under orders to reach adulthood. He recognizes dangers and opportunities by continually referring the information flowing in from his sensory apparatus to his inherited memory. He certainly has not learned his behavioral responses from his parents, never having met them. It is the inherited computer which tells him what to do from one millisecond to the next. He survives or not, partly by luck but also partly according to whether his own inherited variant of the species-specific computer will deliver the right answers to the problems of his own day and place. (The species survives by offering up enough varieties so that some individuals will have what the new situations demand, the wastage of the other individuals being a necessary part of the cost. No other way has yet been discovered for meeting the demands of an unpredictable future, i.e. winning a game the rules for which have not yet been written.)

3. Our earthworm or frog, if lucky, finds himself a sexually mature individual, with his instructions to reproduce now turned on. These instructions, activated by seasonal or other environmental signals operate upon particular genes, particular cells, particular organs, and particular behavioral mechanisms set off through the nervous system. Without knowing it, much less knowing why, the animal seeks out a mate, copulates, and shares in the production of fertilized eggs that bring us again to phase 1 of the cycle.

4. Having blindly and without thought followed his instructions to (1) develop, (2) make do, survive, gain strength, and (3) reproduce, our earthworm or frog subsequently (4) dies. It is the ancient law. So far as the interests of the individual are concerned, it is absurd.

But now how about man? How unique is he? Does he not learn by experience and education, manage his own life, consciously determine what jobs he shall tackle, what ends he shall serve? My argument that he too is run by an inherited computer program rests partly on the observed fact that (1) he develops, (2) he makes every effort to reach maturity, (3) if lucky enough he sets the cycle going again, and (4) he dies. There is nothing unique about that. Experience, learning, individual preferences serve only for minor embellishments.

I select one case to illustrate that an animal's program is mostly inherited. Four to six weeks after fertilization (depending on temperature) a salamander embryo will have used up its yolk and must by then have acquired an elaborate repertoire of locomotor, hunting-sensory, foodgrabbing and swallowing behavior to keep itself fed and growing. Does the individual learn this behavior by trial and error? No. Starting a day before any of his muscles were mature enough to contract, you can rear him in a dilute anesthetic solution until he has reached the feeding stage. Put him back into pond water, and in twenty minutes the anesthetic will have worn off and he is swimming, hunting, grabbing and swallowing like a normal tadpole. One is seeing here the computer-controlled maturation of a computer-controlled behavior. No practice, no learning. The individual within which this remarkable apparatus matures is an expendable pawn, and the apparatus is not for his enjoyment of life, it is to keep the species going.

The Secondary Computer. There is such an inherited program in the human individual, but there is much more. The baby does not so much learn to walk as to develop the inherited capacity to walk; but then he can learn a dance that no man has ever danced before, he can paint a picture with a brush clasped between his toes. During late fetal life and his first six or eight years he gradually matures a second computer system superimposed on, con- trolling and almost completely masking the ancient frog-type computer. The evolutionary history of this new device is traceable back to, and in some respects beyond, the time of origin of the modern mammals 70 million or more years ago. It has progressed farthest in particular mammalian orders - the carnivores, hoofed animals, bats, whales and primates, and least in the egg-laying mammals and marsupials.

The new trend has worked certain real advantages, and has been kept under reasonable control, in the higher mammals, but it is my strong suspicion that its over-development in man is the root of our trouble. Like the dinosaurs, we contain in our own structure the reason why we will have to go. Robinson Jeffers16 said it: "We have minds like the fangs of those forgotten tigers, hypertrophied and terrible."

Up to a point, the development of brain and spinal cord follows the same course in frog and man. Sense organs, cranial and spinal nerves, principal subdivisions of the brain, basic fiber tract systems, all form in strictly comparable fashion in both. But the adult human brain is a far different thing from the adult frog brain. It continues the multiplication and interconnection of neurons during a far longer growth period, and adds to the elementary or frog-type apparatus two principal complicating tissues that far overshadow the earlier developments. One is often called reticular substance, the other is the cerebral cortex.

The reticular substance is so called because it is an interweaving of small centers of gray substance with short bundles and interspersed mats of axons (the white substance), quite different from the simple contrast between gray and white substance seen in primitive animals and in early embryos. The frog brain is not without this sort of tissue, but in the brains of advanced vertebrates like the teleost fishes, the reptiles and the birds, it becomes indescribably complex. The modern mammals push this development to still higher orders of magnitude.

Although neurological science is not yet ready with answers to most specific questions about what happens where in the central nervous system, the new techniques of exploration within the brain suggest that in and through the reticular substance the connections for integrating sensory information with the devices for evaluation and for making decisions and coordinated responses are multiplied exponentially.

Thus, an electrode planted within a single neuron in the reticular substance of the hindbrain can give startling evidence that this one cell is receiving and reacting to sensations reported from widely scattered parts of the body, and sending out coded pulses as a calculated response. Your own brain contains hundreds of millions, probably billions of such cells, every one individually a computer.

The neurologists can now stimulate chosen localized areas through implanted electrodes, either hooked up to wires dangling from the cage ceiling or activated through miniaturized transmitters healed in under the scalp and controlled by radio transmission. In such experiments, stimuli delivered to many parts of the reticular substance cause the animal to react as though he were flooded with agreeable sensation. If the cat or rat or monkey learns how to deliver the stimulus to himself by pressing a pedal, he will do so repeatedly and rapidly, until he falls asleep exhausted. As soon as he wakes up, he goes to pounding the pedal again.

There are other reticular areas which have the reverse effect. If the stimulus comes at rhythmical intervals and the animal discovers that he can forestall it by pressing the pedal, he quickly learns to regulate his life so as to be there and step on it just in time. What kind of sensation such a stimulus produces in him can only be guessed by the experimenter. One might suppose that these areas of reticular substance which have such opposite effects are there 10 add into the computer's analysis of the situation at the moment a go signal or a stop signal for particular alternative choices, or a sense of goodness or badness, satisfaction or distress, urgency or caution, danger or relaxation. A value judgment, in other words.

It is not difficult to see the survival value of such a device. No doubt the basic mechanism exists in the brains of fishes and frogs, though I am not aware that experiments have been done to locate it. In the reticular substance of mammals, however, we see it hugely developed. The result of overdoing this might produce an awareness of the good and bad features of so very many facets of a situation as to delay and perplex the individual in calculating his single coordinated response.

Mammals are also conspicuously good at remembering experiences from their own lives as individuals, and these memories are loaded with value judgments. There is still no clear answer as to where or in what coded form these new personal memories are stored. But an animal with all this added to the ancestral memory, enhanced with perhaps casually acquired and unwisely generalized connotations of goodness and badness, might predictably be endowed with excessive individuality, prone to unnecessarily variable behavior, chosen more often for self-satisfaction than in the interest of species survival.

The other evolutionary development, the formation of the cerebral cortex, is almost unknown in vertebrates other than mammals, and is feeble in some of these. Cerebral cortex is a tissue of awesome complexity, and our techniques for analyzing what happens in it are still highly inadequate. Stimulation of willing human subjects, in chosen spots exposed surgically, or radio stimulation of these areas through permanently installed electrodes operated by healed-in transistor devices, evoke feelings referred to a particular part of the body, or cause normal-appearing localized movements, e.g. the flexion of an arm or a finger, time and again, upon repetition of the signal. Other areas produce more generalized sensory or motor or emotional or physiologic effects. The patient, his brain exposed under local anesthesia, does not know when the stimulus is applied. When the electrode touches a particular spot of his cortex he may report that he is suddenly remembering a scene identifiable as to time and place, but the memory blocks out when the current is off. Stimulation of other areas may elicit emotions of sexual attraction or anxiety or rage graded according to the intensity of the signal.

More wide-ranging experiments with cats, monkeys or barnyard stock, singly or in groups, free to move in large caged areas, show the possibility of turning on and off a great range of complex emotions, behavior, and even personality traits, by local stimulation.17 The effect produced through a permanently planted electrode is area specific. Though not predictable before the first stimulus is given, the response is repeated with each stimulus, many times a day or over periods of months or years.

In subjective comparison of mammals with greater or less personal individuality one gets the impression that the degrees of freedom of choice, of imaginative recognition of possible ways to react to situations, of storage capacity and retentiveness of memory, and the richness of association, are correlated with the intricacy and amount of the cerebral cortex and reticular substance. Animals highest on both scales include porpoises, elephants, cats and dogs, apes, and people.

One cannot underestimate the effects on the human species of other evolutionary trends that came to a climax in us, for instance the development of upright posture that frees the hands, the reshaping of the fingers for grasping and manipulating, the perfection of binocular vision that can bring either the hands or the far distance at will. Far more significant than these was the development of speech, made possible by and controlled in a particular small area of the new cerebral cortex. This expanded the powers of the human secondary computer by orders of magnitude,, even in comparison with that of close relatives like apes.

We no longer communicate with each other by baring teeth, raising hackles and flaunting rumps, but in symbolic language. We can make abstractions and generalizations and artificial associations. Through speech we can feed into the recording apparatus of each other's secondary computers not only the vast and rather accidental store of individually acquired and long-lasting memories of our own experience, but also the loads of approval or disapproval which we deliberately or unwittingly put upon them. We increasingly remove ourselves into created worlds of our own, calculating our choices by reference to a memory bank of second-hand ghosts of other people's experiences and feelings, prettied up or uglified with value judgments picked up who knows where, by whom, for what reason.

Language gave a fourth dimension to the powers of the secondary computer, and writing a fifth dimension. We can now convince each other that things are good or bad, acceptable or intolerable, merely by agreeing with each other, or by reciting catechisms. With writing we can color the judgments of people unborn, just as our judgments are tailored to the whim of influential teachers in the past.

Symbols have given us the means to attach a value judgment to some abstract noun, some shibboleth, and transfer this by association to any person or situation at will. We invent, we practice, we delight in tricks for saying things indirectly by poetry and figures of speech, that might sound false or trite or slanderous or nonsensical if we said them directly. A more normally constructed animal, a porpoise or an elephant, mercifully spared such subtleties, might well look at human beings and see that each one of us has become to some degree insane, out of touch with the actual world, pursuing a mad course of options in the imagined interest of self rather than of species.

The primary computer is still there, programmed in the interest of species survival. With his new powers, man should do better than any other animal at understanding the present crisis and generating an appropriate strategy and tactics. Instead, the effort is drowned out in the noise, the flicker-bicker, the chattering flood of directives from the personalized secondary computer. In pursuit of his own comfort and his own pleasure, man wars against his fellows and against the good earth.

The frame of each person is like a racing shell with two oarsmen in it, back to back, rowing in opposite directions. The one represents the ancient computer system, comparing the personal situation of the moment with an inherited value system and driving the person to perform in such a way that the species will survive, irrespective of how absurd his own expendable life may be. The other represents the secondary computer system, probably located in reticular substance and cerebral cortex, surveying chiefly the memories of childhood and adult life, and deciding how to act according to the value-loaded store of personal experience.*

It is this runaway evolutionary development of our superimposed second computer that has produced our inventors, our artists, our saints and heroes, our poets, our thinkers. Our love and hate, ecstasy and despair. The infinite variety of human personalities. It has also atomized the species into a cloud of ungovernable individuals. We split our elections 48 to 52, make laws to break them, and either ignore community priorities or establish them by political blind-man's-buff in frivolous disregard of real emergencies. Six experts will come violently to six different decisions on how to meet a crisis because their personal histories lead them to weight the same data differently. Each of us can see bad logic and conflicts of interest affecting the judgment of most of our associates; it is more difficult to detect them in ourselves. Our individually acquired prejudices have been built into our secondary computers.

Yet it is a glorious thing to feel the uniqueness, the power of decision, the freedom of being human. Who would prefer to be even so wonderful a creature as a dog, an elephant, a horse, a porpoise? I believe nevertheless that just this ungovernable power of the human individual, the essence of our humanity, is the root of our trouble.

The California biologist Garrett Hardin, in a famous essay called "The Tragedy of the Commons," showed that this accounts for practically all the facets of our apocalyptic crisis, from the population explosion to runaway technology.18 He is referring to the community pasture where anyone may feed his animals. Overgrazing will bring erosion and irreversible deterioriation in it. Each herdsman, calculating the advantage and disadvantage to himself of putting out one more animal to graze, balancing his small share of the possible damage against his sole ownership of the extra income, adds another animal in his own interest, and another, and another. All do, and all lose together. The tragedy is the inescapable disaster when each herdsman pursues his own advantage without limit, in a limited commons. This is the tragedy that leaves us with too many human mouths to feed, soil impoverished and washed or blown away, forests skinned off, lakes ruined, plastic bottles and aluminum cans scattered over the countryside, rivers clogged with dead fish, bilge oil spreading on public waters, streets and highways made obscene with advertisements. It is what gives us choking smog, the stink and corruption below paper mills and slaughter houses, the draining of one well by another in a falling water table, the sneaking of radioactive wastes into the air and the oceans. . .. * i i i 'it.

All these, Hardin makes clear, are problems with notechnological solution. To be sure, the technology stands ready, but the trouble starts with some individual, you, me, whose response to a situation is to give highest priority to his personal chance of profit, or his family's, or his country's. He has a vivid sense of the value to himself of his own freedom, but the total effects of all such freedoms on the species and on the natural world which supports it is invisible or far out of focus. The technology might just as well not exist.

Some of these problems that will not be solved by technology alone can indeed be brought under control by compacts, treaties, and other agreements between willing groups, or by 'laws imposed by the majority upon a minority in the common interest. Hardin, however, puts the finger on the population problem as the worst example of the worst class of problems, in which all of us must restrict the freedom of all of us, when none of us want to. He is properly skeptical of conscience or altruism as forces for uniting the community when nearly all of us are still daring to gamble on the continued capacity of the commons to withstand collapse. What is needed, he says, is a fundamental extension of morality.

My way of agreeing with him is to say that human nature is our chief enemy because the species-preserving function of our primary computer has not yet been built into the secondary computer which generates our human nature. It is by now clear that our nature as individuals is not so much inherited as learned by babies as they grow into people, in and from their individual, accidental and culture-bound experiences. We need to incorporate into the decision-making apparatus that will really control them a new survival morality, a system of values the principal axiom of which is that anything which threatens the welfare of the species is bad, anything that serves to bring the species into harmony with its environment is good. We must, each of us, because of this inner drive, regulate our numbers and our selfish wants as rigorously as the forces of natural selection would have done had we not learned how to set them aside.

Do we know how to create a human nature that can keep the species going without undue sacrifice of the privilege and joy of being human? How much freedom must we give up? Do we want to? Is there time?

REFERENCES

1. Pierre LeCompte du Noüy, 1947, Human Destiny. Pierre Teilhard de Chardin, 1959, The Phenomenon of Man. Edmund W. Sinnott, 1955, The Biology of the Spirit. Anyone inclined toward these mystics should consult G. G. Simpson, 1964, This View of Life.

2. Alan'Gregg, 1955. Science 121: 681. A medical aspect of the population problem.

3. E. F. Moore, 1956. Scientific American 195: 118. Artificial living plants.

4. J. Keosian, 1964, The Origin of Life.

5. B. Infelder and J. Piaget, 1958, The Growth of Logical Thinking.

6. L. H. Day and A. T. Day, 1964, Too Many Americans.

7. R. Nixon, 1969. Message to Congress, July 19.

8. D. B. Luten, 1964, Sierra Club Bulletin 49: 43. Numbers Against Wilderness.

9. K. Davis, 1967, Science 158: 730. Population Policy: Will Current Programs Succeed? B. Berelson, 1969, Science 163: 533. Beyond Family Planning.

10. C. R. Wharton, 1969, Foreign Affairs, April. The Green Revolution: Cornucopia or Pandora's Box?

11. W. and P. Paddock, 1967, Famine 1975!

12. C. F. Park, 1968, Affluence in Jeopardy; Minerals and the Political Economy.

13. L. C. Cole, 1966, Bioscience 16: 243. Man's Ecosystem. C. A. Smith and L. C. Cole, 1970, letters in Bioscience 20: 72, following L. C. Cole, 1969, Bioscience 19: 989. Thermal Pollution. Cf. also S. Novick, 1969, The Careless Atom.

14. G. Borgstrom, 1969, Too Many.

15. L. White, 1967, Science 155: 1203. The Historical Roots of Our Ecologic Crisis.

16. R. Jeffers, "Passenger Pigeons," in The Beginning and the End.

17. J. M. R. Delgado, 1969, Physical Control of the Mind.

18. G. Hardin, 1968, Science 162: 1243. The Tragedy of the Commons.

* Independently, participants in Alumni College sessions both in Hanover and in California recognized these antagonistic computers as the two oarsmen of the Apocalypse.

Professor Ballard (foreground), whose lectures appear here,shown listening to an Alumni College faculty colleague.

On their way to a coffee break after two morning lectures.

Planned Parenthood World Population

Some members of a post-lecture discussion group.

Planned Parenthood World Population

The book assigned as advance reading for Professor Ballard's course was Famine 1975! by William and Paul Paddock.