William Catton. 1980. Overshoot: The Ecological Basis of Revolutionary Change. University of Illinois Press.

Origins of Man’s Future

We are already living on an overloaded world. Our future will be a product of that fact; that fact is a product of our past. Our first order of business, then, is to make clear to ourselves how we got where we are and why our present situation entails a certain kind of future.

To this purpose, consider the information about the human saga assembled in the table below.

Taken a row at a time, this table tells an enormous (and enormously revealing) story. It is the story of a world that has again and again approached the condition of being saturated with human inhabitants, only to have the limit raised by human ingenuity.

The first several rounds of limit-raising were accomplished by a series of technological breakthroughs that took almost two million years. These breakthroughs enabled human populations repeatedly to take over for human use portions of the earth’s total life-supporting capacity that had previously supported other species. The most recent episode of limit-raising has had much more spectacular results, although it enlarged human carrying capacity by a fundamentally different method: the drawing down of finite reservoirs of materials that do not replace themselves within any human time frame. Thus its results cannot be permanent. This fact puts mankind out on a limb which the activities of modern life are busily sawing off.

Table 1 History of Major Technological Breakthroughs and Ensuing Population Increases

In the Beginning

Some two million years ago, as represented in the first row of Table 1, creatures of another species – human, but not our kind of human – had evolved from pre-human ancestors by finding themselves more and more adapted to a place in the web of life somewhat different from the place their ancestors had occupied. They had discovered somehow that they could use (rather than merely avoid) fire; they could warm themselves with it, ward off predators with it, cook with it and thus render digestible certain organic substances that would not otherwise have been available to their bodies as nutrition. Whatever the world’s capacity had been for supporting their pre-human ancestors, there was now an additional place for the human descendants of those earlier creatures. Their human traits enabled them to live partly upon portions of the world’s substance not usable by their forebears.

These newly human beings had also begun to make and use simple tools. Moreover, they could teach their progeny how to make and use these artifacts. Each generation did not have to rediscover independently the techniques that had contributed to its parents’ survival. Still, the accumulation of adaptive culture would have been prodigiously slow at first, and for hundreds of thousands of years there could not have been very many of these creatures. Even with fire, tools, and traditions, these humans remained what their prehuman ancestors had been: consumers of naturally available foodstuffs obtained from wild sources by hunting and gathering.

There were no census bureaus in Paleolithic times, of course. But by knowing the dependence of early man upon wild food sources, we can make reasonable estimates of maximum feasible average population density, and can estimate the extent of the earth’s land area capable of supporting such hunters and gatherers. The important fact that emerges is that there could never have been very many millions of them. Nevertheless, these early humans were successful; they survived, reproduced, adapted, and continued evolving.

By the time almost 80,000 generations of human hunters and gatherers had lived, their biological and cultural responses to the selection pressures imposed by their spreading habitats had given rise to a descendant population with essentially the inheritable physical traits we see among men and women today. Thus by about 35,000 BC, the humans on earth were of our own species, Homo sapiens. Probably about three million of them were living by gathering and hunting.

Increased Hunting Proficiency

We cannot really say that three million was the maximum number the Earth could ever have supported in the manner in which they were then living. Still, we can be reasonably sure, from their slow attainment of even that number, that the earth’s carrying capacity for that kind of creature with that kind of lifestyle was not much greater than that figure. However, the gradually evolving cultures of Homo sapiens eventually increased the earth’s human carrying capacity.

About 35,000 BC, someone discovered how much harder and farther a spear could be thrown if the thrower effectively lengthened his arm by fitting the end of the spear into a socket in the end of a handheld stick. Someone else invented a way of propelling miniature spears (arrows) not only faster, but also in a manner that permitted line-of-sight aiming, by fitting their notched ends to a cord tied to the two ends of a springy stick. Using tools like the spear-thrower and the bow and arrow, humans became more proficient hunters, and more of the earth’s game animals became nourishment for human bodies.

With these technological breakthroughs, the worldwide population of Homo sapiens increased in a little over one thousand generations from about three million souls to about eight million. The total human biomass on earth had more than doubled. Still, most of the people in each of those thousand generations would have been utterly unaware of increase, for, as the entry in the far right-hand column of the table shows, each tribe was enlarged on the average by less than 1/10th of one percent during one generation – that is, during roughly the quarter century it took for each new parent to raise his own children and reach grandparent status.

Learning to Manage Nature

But the time came, eventually, for another major breakthrough and another enlargement of the earth’s human carrying capacity. Somewhere, some of the people who gathered wild seeds for grinding into flour observed that seeds spilled on moist earth near where the family carried on its activities sprouted into plants that grew at least as well as those in the wild. In time these plants would bear a new crop of seeds, conveniently harvestable. Homo sapiens went on to develop this discovery into techniques of plant cultivation, effecting a major transformation of the relation of our species to nature’s web of life. Henceforth, some of us were going to obtain nourishment from a humanly managed portion of the biotic community, rather than merely gathering the products of plant and animal species that we could use if we reached them before other consumer animals or invisible decomposer organisms.

This horticultural revolution, by which hunters and gatherers turned into farmers, was followed by a tenfold increase in the earth’s human population. This increase occurred in 1/6th as many generations as the previous increase phase. Such acceleration indicates that mankind’s daring to undertake the management of a portion of nature had again raised the earth’s human carrying capacity. Biologically, this species, with the remarkable capability of achieving cultural innovations, was proving a resounding success.

It began to be possible for a minuscule but increasing fraction of any human tribe to devote its time to activities other than obtaining sustenance. Human social organization could begin developing along more elaborate lines, and the fate of cultural innovation could further accelerate. Each increment of technology gave mankind a competitive edge in interspecific competition. Our species was well on its way to being the dominant member of the ecosystem.

Compound Interest

Note that, even after this horticultural acceleration of population growth, change would have remained almost unnoticeable to those living through it. The increment in an average generation was still a mere 1.5 percent. The starting population of 8 million was, in effect, multiplied in one generation by a factor of 1.015, and then that product was again multiplied in the next generation by 1.015, and so was that product, and so on. The “interest” of 1.5 percent on the initial “investment” was compounded by each generation – 160 times between 8000 BC and 4000 BC. Thus:

8, 000,000 x (1 + 0.015) to the 160th power = 86,000,000, approximately.

So the numbers shown in the “generations elapsed” column of Table 1 are more than just expressions of the time intervals between the dates shown in the first column; they must be read as exponents applied to multipliers that are derived from the figures in the last column. Even at low percentage rates of increase per generation, the “compound interest” pattern can produce great change when enough generations elapse.

As advancing human culture extended the niches available to mankind, recurrent surges of essentially exponential growth in numbers became possible. (The well-known “population explosion” of our own time was merely the most recent episode in a process that has been going on since antiquity.)

Tools, Organization, and Standard of Living

By about 4000 BC, stone and bone tools began to be augmented and then superseded by metal tools as Homo sapiens moved into what his history-writing descendants would one day label the Bronze Age. This enhancement of man’s tool kit was followed by further population increase. Metallurgy enhanced the ability of the human species to harvest nature’s products, rather than leaving them to be used by other consumer species. It also gave further impetus to the elaboration of a “division of labor” among increasingly specialized occupations. From here on, the growth of organization among humans would be an increasingly important factor in their dominance over the environment supporting them.

If cultural innovations were to cease, or if some ultimate limit proved impossible to transcend by cultural progress, exponential growth would give way to a curve of diminishing returns. Limited carrying capacity would reduce the rate of growth in successive generations. Eventually, as population approached carrying capacity, the growth rate would approach zero-of necessity. That is what “carrying capacity” means.

But innovations continued, and the ceiling was raised again. Around 3000 BC, man the cultivator of plants went in for an early version of “mass production”, tilling land in larger tracts than before. This was made possible by invention of the plow, which enabled the farmer to begin using non-human energy to turn over the soil – energy supplied by the muscles of an ox or a horse, though at first a plow was sometimes pulled by a slave or a wife (and had to be rather small). One farmer could manage more soil with this additional tool. But an agriculture that used draft animals had to use some of its land to raise crops to be eaten by those animals, so this new technology would not immediately raise human carrying capacity as dramatically as previous innovations had done.

There was also an alternative use for this particular increment in sustenance-producing power. A farmer with a plow and a draft animal could farm enough land to feed himself, the animal, his own family, and perhaps have a bit to spare. So some small but gradually increasing fraction of the population could now do things other than raise food. Human groups could opt for further elaboration of their lives, rather than for simple expansion of their numbers.

About 1000 BC, iron tools began to supplement and replace those made of bronze. Again, some of the carrying capacity increment was used to enhance, little by little, the standard of living of at least some groups.

The separate effects of these last several innovations upon population increase cannot be assessed, because usable estimates of population numbers at the times these new tools and techniques came into use are not available. But between the beginning of the Bronze Age and the birth of Christ (a date for which there does happen to be a more or less agreed upon population estimate) their cumulative effect was to expand the world’s human stock from about 86 million to about 300 million – an average rate of increase of about 3/4ths of one percent per generation. Slower increase continued for another millennium.

Firearms

Then came a different kind of breakthrough. Early in the 14th century firearms were invented, and were immediately put to military use. The first firearms were hardly portable, and hardly suitable for any non-military purpose. If they were to have any effect on carrying capacity, that effect had to be indirect. By changing the nature of warfare they would eventually change the nature of political organization, which would, in turn, alter the way human populations would relate themselves to the resources of the world around them.

Within three generations after these first firearms came into use, hand-carried firearms began to be made. Since these could have had some direct bearing upon human ability to harvest meat, they (rather than their more cumbersome military forerunners) are given a place in Table 1. In the next sixteen generations, we see a higher average rate of population increase than ever before. It is too high, in fact, to be solely due to improved game-harvesting efficiency. It came about quite differently.

The cumulative effects of human increase over the past two million years were becoming significant. The portions of the earth’s land surface available to those human tribes that had thus far experienced all of these technological breakthroughs were coming to be rather fully occupied by humans. But the tools and the knowledge available to these culturally most advanced segments of Homo sapiens were enabling (and causing) some men to leave the land and venture more and more daringly onto the sea. Less than a century after the invention of portable firearms, Europeans would discover lands they had not previously known existed. In the generations after that discovery, the Europeans’ superiority in weapons would enable them to take possession of whole new continents whose prior human inhabitants were much less numerous, because they were still living mostly at the Stone Age hunter-gatherer or early horticultural level.

Firearms did not enlarge the planet. However, they served to enlarge once again the carrying capacity of the world known to Europeans, by making available for settlement and exploitation a “virgin” hemisphere. The expansion of territory available for use by Europe’s already advanced means is the main reason why firearms can be said to have led to the unprecedented rate of increase in human numbers during this last portion of the agrarian period.

Abundance

I shall call the centuries that followed the sudden expansion of European man’s habitat by voyages of discovery the Age of Exuberance, for reasons to be spelled out in later chapters. During that age, man largely forgot that the world (that is, Europe) had once been saturated with population, and that life had been difficult for that reason. Discovery of the New World gave European man a markedly changed relationship to the resource base for civilized life. When Columbus set sail, there were roughly 24 acres of Europe per European. Life was a struggle to make the most of insufficient and unreliable resources. After Columbus stumbled upon the lands of an unsuspected hemisphere, and after monarchs and entrepreneurs began to make those lands available for European settlement and exploitation, a total of 120 acres of land per person was available in the expanded European habitat – five times the pre-Columbian figure!

Changelessness had always been the premise of Old World social systems. This sudden and impressive surplus of carrying capacity shattered that premise. In a habitat that now seemed limitless, life could be lived abundantly. The new premise of limidessness spawned new beliefs, new human relationships, and new behavior. Learning was advanced, and a growing fraction of the population became literate. There was a sufficient per capita increment of leisure to permit more exercise of ingenuity than ever before. Technology progressed, and technological advancement came to be the common meaning of the word “progress”.

But the aura of limitless opportunity had another effect: further acceleration of population growth. To go into some details not shown explicitly in Table 1, between 1650 and 1850, a mere two centuries, the world’s human population doubled. There had never before been such a huge increase in so short a time. It doubled again by 1930, in only eighty years. And the next doubling was to take only about forty-five years! As people and their resource-using implements became more numerous, the gap between carrying capacity and the resource-use load was inevitably closed, American land per American citizen shrank to a mere 11 acres – less than half the space available in Europe for each European just prior to Columbus’s revolutionizing voyage. Meanwhile, per capita resource appetites had grown tremendously. The Age of Exuberance was necessarily temporary; it undermined its own foundations.

Most of the people who were fortunate enough to live in that age misconstrued their good fortune. Characteristics of their world and their lives, due to a “limitlessness” that had to be of limited duration, were imagined to be permanent. The people of the Age of Exuberance looked back on the dismal lives of their forebears and pitied them for their “unrealistic” notions about the world, themselves, and the way human beings were meant to live. Instead of recognizing that reality itself had actually changed – and would eventually change again – they congratulated themselves for outgrowing the “superstitions” of ancestors who had seen a different world so differently. While they rejected the old premise of changelessness, they failed to see that their own belief in the permanence of limitlessness was also an overbelief, a superstition.

As the gap closed, conditions of life did change – of necessity. The world reentered an age of population pressure. Its characteristics had to resemble, in certain ways, the basic features of the Old World of pre-Columbian times. Except that now there were ever so many more human beings, all parts of the planet were in touch with each other, per capita impact on the biosphere had become enormously amplified by technology, depletion of many of the earth’s non-renewable resources was already far advanced – and the inhabitants of this post-exuberant world had acquired from the Age of Exuberance expectations of a perpetually expansive life.

The Takeover Method

The Europeans who began taking over the New World in the sixteenth and seventeenth centuries were not ecologists. Although they soon were compelled to realize that the Americas were not quite uninhabited, they were not prepared to recognize that these new lands really were, in an ecological sense, much more than “sparsely” inhabited. This second hemisphere was, in fact, essentially “full”. As we have seen, the world supported fewer people when they were at the hunter-gatherer level than when they advanced to the agrarian level. In the same way, a continent that was (ecologically speaking) “full” of hunters and gatherers was bound to seem almost empty to invaders coming from an agrarian culture and accustomed to that culture’s greater density of settlement.

Ethnocentrism prevented most Europeans from seeing themselves as they must have appeared to the Indians – as competitors for resources the Indians were already exploiting as fully as they knew how. Ecologically, these vast “new” lands did not have “plenty of room” for Indians plus Europeans, as the Europeans easily supposed. Indians living by hunting-gathering and by simple horticulture were going to be displaced by incoming hordes of Europeans practicing advanced agrarian life.

Even if there had been less ethnocentrism, and if principles of Christian compassion had sufficed to preclude all suspicion, hostility, and bloodshed in the interactions between “civilized” and “savage” peoples, total ignorance of the ecological implications of different levels of technology would have enabled the takeover to occur. Europeans were able to move to the New World with no pangs of conscience about relegating the native peoples to a shrinking fraction of these continents. The shrinking fraction afforded insufficient carrying capacity (when exploited by hunting and gathering or by primitive horticulture) to accommodate the number of Indians already generated by their previously more extensive environment. But neither the concept of carrying capacity nor its relation to stages of human culture was part of the European settlers’ mental equipment. So the displacement occurred.

Essentially the same displacement followed from the same ethnocentrism and ecological naivete when settlers from Europe invaded Australia and New Zealand. An approximation of this pattern also prevailed for a while as Europeans later took over the more or less temperate parts of Africa, although there a difference in the invader/native ratio eventually began to reverse the relationship with more numerous Africans eventually beginning to oust Europeans.

All over the world, Europeans had acted on the premise that it was only fair and reasonable for “unused” or “underused” lands (that is, lands being used by non-agrarian non-Europeans) to be “put to good use”. In the absence of ecological understanding, that premise had seemed utterly sound.

The takeover method of enlarging carrying capacity was far older than the Age of Exploration and the centuries of colonial expansion. Invading and usurping lands already occupied by others was essentially what mankind had been doing ever since first becoming human. Each enlargement of carrying capacity reviewed in the preceding pages consisted essentially of diverting some fraction of the earth’s life-supporting capacity from supporting other kinds of life to supporting our kind. Our pre-sapiens ancestors, with their simple stone tools and fire, took over for human use organic materials that would otherwise have been consumed by insects, carnivores, or bacteria. From about 10,000 years ago, our earliest horticulturalist ancestors began taking over land upon which to grow crops for human consumption. That land would otherwise have supported trees, shrubs, or wild grasses, and all the animals dependent thereon – but fewer humans. As the expanding generations replaced each other, Homo sapiens took over more and more of the surface of this planet, essentially at the expense of its other inhabitants. At first those displaced were creatures with teeth and claws instead of tools, with scales or feathers or fur instead of clothes.

In this takeover process, man was behaving as all creatures do. Each living species has won for itself a place in the web of life by adapting more effectively than some alternative form to a given role. What is true of a species is also true of a subdivision within a species. A given tract of land has greater carrying capacity for the subspecies that can extract more from it than for other portions of the species that happen to be less equipped to exploit it.

None of this is said for the sake of justifying displacement of American Indians (or Polynesians, Aborigines, or Africans) by Europeans. Recently aroused pangs of guilt have made European-descended Americans more conscious of the suffering of those who were displaced. Although guilt feelings cannot resurrect the Indians who were forced to yield their place to more powerfully equipped Europeans, perhaps such feelings can prompt us to think about matters we might otherwise have continued to neglect. By explaining this human displacement episode as a special case of the ecological principle of “competitive exclusion”, we can at least take note of how common the takeover process has been in the ecological history of the world. Then, having seen that, we should also be able to see how fundamentally different the takeover method was from another method by which human carrying capacity has been most recently stretched. Recognition of the difference is essential to understanding the human predicament.

The Drawdown Method

About 1800 AD, a new phase in the ecological history of humanity began. Carrying capacity was tremendously (but temporarily) augmented by a quite different method; takeover gave way to drawdown. A conspicuous and unprecedentedly large acceleration of human population increase got under way as Homo sapiens began to supersede agrarian living with industrial living.

Industrialization made use of fossil energy. Machinery powered by the combustion of coal, and later oil, enabled man to do things on a scale never before possible. New, large, elaborate tools could now be made, some of which enhanced the effectiveness of the farming that of course had to continue. Products of farm and factory could be transported in larger quantity for greater distances. Eventually the tapping of this “new” energy source resulted in the massive application of chemical fertilizers to agricultural lands. Yields per acre increased, and in time acreages applied to the growing of food for humans were substantially increased – first by eliminating draft animals and their requirements for pasture land, but also by reclaiming land through irrigation, et cetera.

This time mankind was not merely taking away from competitors an additional portion of the earth’s life-supporting capacity. (He was still doing this, and still not recognizing that this was what he had always done. But – worse – he was now also not recognizing the true nature of something else he was doing on a vast scale. So man was painting himself into a corner.) This time, the human carrying capacity of the planet was being supplemented by digging up energy that had been stored underground millions of years ago, captured from sunlight which fell upon the earth’s green plants long before this world had supported any mammals, let alone humans, or even pre-human primates. The solar energy had been captured by photosynthesis in plants that grew and died and were buried during the Carboniferous period, without the efforts of any farmers. (As we shall see in the next chapter, the fact that no farm labor had to be paid to raise the Carboniferous vegetation, and that no investments in farm machinery used to grow those prehistoric “crops” had to be amortized, et cetera, helped get us into our present predicament.)

Carrying capacity was this time being augmented by drawing down a finite reservoir of the remains of prehistoric organisms. This was therefore going to result in a temporary extension of carrying capacity; in contrast, previous enlargements had been essentially permanent, as well as cumulative.

Being impermanent, this rise in apparent carrying capacity begged one enormously important question: What happens if population, as usual, increases until it nearly fills this temporarily expanded set of opportunities, and then, because the expansion was only temporary, the world finds itself (like the Indians on their shrunken territories) with a population excess? What are the implications of a carrying capacity deficit for mankind’s future? What happens, for example, when supplies of oil become scarce, when tractor fuel becomes unavailable or prohibitively expensive, and when farmers again have to take 1/4th to 1/3rd of the land on which they now raise food for humans and convert it instead to raising feed for draft animals?

Such questions were not asked as long as we viewed our world with a pre-ecological paradigm. The myth of limitlessness dominated people’s minds. Had anyone conceived such implausible-seeming questions in the Age of Exuberance, the answer might have seemed equally incredible: post-exuberant nations and individuals would have a compulsive need to deny the facts so as to deny their own redundancy. (We shall examine such denial of the new reality in Part III of this book, and again in Part V).

Industrialization came about at a fast enough pace so that it enlarged per capita wealth and was not entirely devoted to enlarging population. In principle, any increase in carrying capacity – temporary or permanent – affords a choice between enabling the same number of individuals to live more lavishly or enabling a larger number of individuals to live at previous standards. When the enlargement of carrying capacity is modest and is spread over many generations, it tends to be used mainly to increase numbers; if it is enormous and comes so suddenly that human numbers just don’t rise at the same pace, it raises living standards. The European takeover of the New World had enlarged carrying capacity (for Europeans) just fast enough to begin having this salutary effect. By drawing down stores of exhaustible resources at an ever-quickening pace, industrialization (temporarily) augmented carrying capacity even faster, affording opportunity for quite a marked rise in prosperity and for a phenomenal acceleration of population increase. The welcome rise in prosperity reinforced the dangerous myth of limitlessness and obscured for a while the hazards inherent in the population increase.

Overshoot Aggravated

Scarcely more than two generations had tasted the fruits of industrialization when the growth of population was still further accelerated by truly effective death control. The role of micro-organisms in producing diseases was discovered. In 1865 the practice of antiseptic surgery began. It serves in Table 1 as a reasonable demarcation of the beginning of an era filled with related breakthroughs in medical technology: hygienic practices, vaccination, antibiotics, et cetera. The total effect of this recent series of achievements has been to emancipate mankind more and more from the life-curtailing effects of the invisible little creatures for which human tissues used to serve as sustenance. Like other prey species newly protected from their predators, we have been fruitful and have so multiplied that we have much more than “replenished” the earth with our kind.

These achievements in death control re-channeled the effects of industrialization; they increased the rate at which human population could increase. More of the unprecedentedly rapid rise in apparent carrying capacity resulting from industrial drawing down of resource stocks was devoted to supporting population growth, and less was devoted to supporting enhanced living standards, than might otherwise have been the case.

Death control was a real boon to the first three or four generations that experienced it. Increasingly, parents were spared bereavement during their child-rearing years, and people of all ages were spared the suffering and debilitation that infectious diseases used to inflict. Fewer children became orphaned. Fewer adults became widowed in the prime years of life.

But all these benefits helped us to overshoot permanent carrying capacity. For most people, as this was happening, “carrying capacity” remained an unknown phrase. The concept was absent from the paradigm by which people in the Age of Exuberance perceived and understood their world. Industrialism had given us a temporary increase in opportunities – a very dangerous blessing. Death control gave us a further rapid increase in population not based on a further rise in carrying capacity. Thus, in the seven generations since 1800, world population quadrupled, and mankind came into a really precarious situation.

The precariousness remained unseen by many. Looking back on a century or two of remarkable technical achievements, accompanied by growth of human numbers that was itself culturally defined as a kind of progress (as every town aspired to become a city), minds that had not yet learned the distinction between methods of boosting carrying capacity and methods of overshooting it foresaw no insurmountable difficulty in simply repeating past breakthroughs. It was imagined, for example, that “fast breeder reactors” and other technological eggs-not-yet-hatched could be counted on to provide further increments of carrying capacity whenever nature’s limits began to hurt. (This attitude will be given a suggestive name in Chapter 4 and explored further in Chapter 11.)

During World War II, the brashly American words of a popular song proclaimed: “We did it before, and we can do it again!” A generation after that conflict, we seemed to be taking a demilitarized version of that cliche as the basis for presupposing the supportability of further increases in the population-technology load upon finite environments. People displayed either persistent ignorance of the carrying capacity concept, or naive faith that carrying capacity could always be expanded, that limits could always be transcended. Such an assumption seemed to underlie the stubborn refusal of capitalists and Marxists alike to acknowledge that the myth of limitlessness had at last become obsolete. There was also the assumption that further advances in technology would necessarily enlarge carrying capacity, not reduce it. Enlargement of carrying capacity had been the role of technology in the past; however, we shall see (in Chapter 9) that there has been a reversal of this role in the industrial era. Technology has enlarged human appetites for natural resources, thus diminishing the number of us that a given environment can support.

Back to Hunting and Gathering

The breakthrough we call industrialism was fundamentally unlike earlier ones. It did not just take over for human use another portion of the web that had previously supported other forms of life. Instead, it went underground to extract carrying capacity supplements from a finite and depletable fund – a fund that was created and buried by nature, scores of millions of years before man came along. The drawdown method that we call industrialism relied for its increase of opportunities upon use of resources that are not renewed in an annual cycle of organic growth. To expect to “do it again” is to expect to find other exhaustible resources each time we use up a batch of them. Only once could the technologically most advanced nations of mankind discover a second hemisphere to relieve the pressure in a filled-up first hemisphere; nevertheless, modern industrial societies have continued to behave as if massive “exploration” efforts could forever continue to “discover” additional deposits of mineral materials and fossil fuels. In short, industrial life depends on a perpetual hunt for required substances. To take one example, in order to continue present rates of use of copper, the United States must each year find 250 million tons of ore (containing 0.8 percent copper) – more than a ton for each of us.

The mineral and fuel deposits upon which we are now so dependent were put into the earth by geological processes that happen only at a pace enormously slow by human standards. Since 8000 BC mankind has been taking over management of contemporary botanical processes, the source of sustenance materials that have renewal times much shorter than a human lifespan. Now we rely, as members of industrial societies, upon other substances with renewal times that may be thousands or even millions of times longer than a human lifespan. Their renewal is by geological processes; present stocks of them were put in place by operation of those processes over immensely long stretches of earth history. Mankind cannot realistically hope to assume management of prehistoric events, or to replenish the ores and fuels now being extracted so ravenously. Instead, we must face the fact that, after ten millennia of progress, Homo sapiens is “back at square one”. Industrialization committed us to living again, massively, as hunters and gatherers of substances which only nature can provide, and which occur only in limited quantity. A major oil company whose credit card has been a convenience to me in my travels has recently confirmed this – unwittingly, of course – by printing at the bottom of my monthly statement a bit of institutional advertising. In an effort to enlist customer support for its resistance to congressional pressures against combined ownership of both “production” and “marketing” facilities, this company’s message proclaims that it “does the whole job – finding and delivering oil products you need” (my italics).

Our species had been an enormous biological success. But success carried to excess can be disastrous. The shift from takeover to drawdown actually yielded excessive success. As we shall see, this situation has had a natural sequel. Much of the turmoil so vexing to the generation that saw the fourth billion added to the world’s human population can be understood in such terms. We had already begun to encounter the penalties of becoming again what our remote ancestors were – consumers of substances provided by nature and not by man, substances we obtain from sources not subject to replenishment by our manipulations. We became heavily dependent upon hunting for natural deposits of these substances, and upon continually gathering vast quantities for our use. Euphemistically calling the new versions of these ancient activities “finding” and “delivering”, or “exploration” and “production”, only blinded us to what we were doing. It did not protect us from the consequences.

Notes

1. Calculations supporting this statement appear in the next chapter; the present chapter tells the story of our arrival in this predicament. For another statement indicating that this is indeed the nature of our situation, see Kingsley Davis, “Zero Population Growth: The Goal and the Means”, Daedalus 102 (Fall, 1973):26.

2. For examples of the reasoning behind any inference as to the size of pre-historic populations, see Hollingsworth 1969; Ehrlich, Holm, and Brown 1976, page 457; Coale 1974, page 41; Desmond 1962, pages 3-4.

3. For documentation of this and subsequently mentioned population estimates, see sources cited in the notes for Table 1.

4. Estimates of prehistoric world populations are less exact than modern population figures, of course; but the increase discussed in this paragraph would be no less significant if its magnitude were appreciably less or somewhat more than stated.

5. See Childe 1951, pages 25-26.

6. In technical terms, carrying capacity is represented by the upper limit of an S-shaped logistic growth curve, into which an initially exponential growth curve gets converted by the finiteness of the habitat and its resources.

7. It was not until the latter part of the seventeenth century that scientific study of population began. A British mathematician, John Graunt, in 1662 studied parish clerks’ records of baptisms and burials, and derived sex ratios, fertility ratios, measures of natural increase, et cetera. In 1693 the astronomer Edmund Halley constructed a life-expectancy table from church records.

8. Webb 1952, pages 17-18.

9. Desmond 1962, page 12.

10. See the brief comments in Boughey 1975, page 17, on “competitive exclusion” and “resource partitioning”, and the more extensive exposition by Hardin 1 960. To recognize the displacement of one population of humans by another (with more advanced technology) as an instance of this common ecological process, it is useful to think in terms of a concept devel oped in Chapters. 6 and 9, “quasi-speciation”.

11. From 1973, as shortages of fossil energy came to public attention, it was often supposed that “energy plantations” would afford a solution. The fact that this would put fuel-burning engines into the same competitive relation with food-consuming humans that formerly applied to farmers’ draft animals was almost universally overlooked.

12. Since “carrying capacity” is by definition the maximum permanently supportable population, the expression “permanent carrying capacity” is redundant. The redundancy may serve, nevertheless, to underscore the nature of our predicament. A related point is made by introducing in the next chapter the concept of “phantom carrying capacity” to refer to such things as fossil energy; to speak of “temporary carrying capacity” would be a contradiction.

Selected References

Ackerknecht, Erwin H. 1968. A Short History of Medicine. Revised edition. New York: Ronald Press.

Borrie, W D. 1970. The Growth and Control of World Population. London: Weidenfeld and Nicholson.

Boughey, Arthur S. 1975. Man and the Environment. 2nd edition. New York: Macmillan.

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