Human population explosion Long time ago, our ancestors, hunters and gatherers, worked four hours a day and enjoyed the unspoiled beauty of wild nature. Some of them proliferated like vermin, conquered other tribes, transformed nature into human feedlot, and traded their freedom for a society of mutual coercion. We have inherited their lustful genes and rapacious culture.

Have you ever roamed a wilderness? I have. When I met strangers, we were friendly because there was nobody else to talk to. If I met the same strangers on a busy street, we would avoid eye contact and walk away.

When the bubonic plague reduced european population, wages rose so much that labor saving machines became indispensable. Industrial revolution followed. Farms located on poor soil were abandoned. It is not hard to imagine the impact of population reduction on our modern society. Housing would become affordable. Traffic jams would disappear. There would be less noise, pollution, and crime. Life would be worth living.

Human population explosion
(data from U.S. Bureau of the Census)

Bruce Sundquist has compiled a review of literature about the Earth's carrying capacity. He believes that the maximum sustainable population of the Earth is about 1 billion people. It is determined by topsoil erosion and salination of irrigated land.

David Pimentel is a professor of ecology and agricultural science at Cornell University. Here are excerpts from his article: "More than 3 billion people worldwide are already malnourished, and 3 billion are living in poverty; grain production per capita started declining in 1984 and continues to decline... Fifty-eight academies of science, including the U.S. National Academy of Sciences, point out that humanity is approaching a crisis point with respect to the interlocking issues of population, natural resources, and sustainability..."

Norman Borlaug won the Nobel Peace Prize in 1970 for his contribution to the Green Revolution. He is the only agricultural scientist ever to win the Nobel Prize. "There can be no lasting solution to the world food problem until a more reasonable balance is struck between food production and human population growth," Borlaug said. "The efforts of those on the food-production front are, at best, a holding operation which can permit others on the educational, medical, family planning and political fronts to launch an effective, sustainable and humane attack to tame the population monster."

Kenyan conservationist Richard Leakey estimates that most wild species will be exterminated in the next 50 to 100 years.

Carrying capacity books and literature review by Ross McCluney.

Excerpt from Robert Kaplan's book The Coming Anarchy.

Population links.

Environmental maps:
human footprint, 800 kB.
last of the wild, 346 kB.
photosynthesis, 119 kB.

The Tragedy of the Commons

by Garrett Hardin

Source: Garrett Hardin, "The Tragedy of the Commons," Science, Vol. 162, 1968, pp. 1243-1248.

At the end of a thoughtful article on the future of nuclear war, J.B. Wiesner and H.F. York concluded that: "Both sides in the arms race are…confronted by the dilemma of steadily increasing military power and steadily decreasing national security. It is our considered professional judgment that this dilemma has no technical solution. If the great powers continue to look for solutions in the area of science and technology only, the result will be to worsen the situation." [1]

I would like to focus your attention not on the subject of the article (national security in a nuclear world) but on the kind of conclusion they reached, namely that there is no technical solution to the problem. An implicit and almost universal assumption of discussions published in professional and semipopular scientific journals is that the problem under discussion has a technical solution. A technical solution may be defined as one that requires a change only in the techniques of the natural sciences, demanding little or nothing in the way of change in human values or ideas of morality.

In our day (though not in earlier times) technical solutions are always welcome. Because of previous failures in prophecy, it takes courage to assert that a desired technical solution is not possible. Wiesner and York exhibited this courage; publishing in a science journal, they insisted that the solution to the problem was not to be found in the natural sciences. They cautiously qualified their statement with the phrase, "It is our considered professional judgment...." Whether they were right or not is not the concern of the present article. Rather, the concern here is with the important concept of a class of human problems which can be called "no technical solution problems," and more specifically, with the identification and discussion of one of these.

It is easy to show that the class is not a null class. Recall the game of tick-tack-toe. Consider the problem, "How can I win the game of tick-tack-toe?" It is well known that I cannot, if I assume (in keeping with the conventions of game theory) that my opponent understands the game perfectly. Put another way, there is no "technical solution" to the problem. I can win only by giving a radical meaning to the word "win." I can hit my opponent over the head; or I can falsify the records. Every way in which I "win" involves, in some sense, an abandonment of the game, as we intuitively understand it. (I can also, of course, openly abandon the game -- refuse to play it. This is what most adults do.)

The class of "no technical solution problems" has members. My thesis is that the "population problem," as conventionally conceived, is a member of this class. How it is conventionally conceived needs some comment. It is fair to say that most people who anguish over the population problem are trying to find a way to avoid the evils of overpopulation without relinquishing any of the privileges they now enjoy. They think that farming the seas or developing new strains of wheat will solve the problem -- technologically. I try to show here that the solution they seek cannot be found. The population problem cannot be solved in a technical way, any more than can the problem of winning the game of tick-tack-toe.

What Shall We Maximize?

Population, as Malthus said, naturally tends to grow "geometrically," or, as we would now say, exponentially. In a finite world this means that the per-capita share of the world's goods must decrease. Is ours a finite world?

A fair defense can be put forward for the view that the world is infinite or that we do not know that it is not. But, in terms of the practical problems that we must face in the next few generations with the foreseeable technology, it is clear that we will greatly increase human misery if we do not, during the immediate future, assume that the world available to the terrestrial human population is finite. "Space" is no escape. [2]

A finite world can support only a finite population; therefore, population growth must eventually equal zero. (The case of perpetual wide fluctuations above and below zero is a trivial variant that need not be discussed.) When this condition is met, what will be the situation of mankind? Specifically, can Bentham's goal of "the greatest good for the greatest number" be realized?

No -- for two reasons, each sufficient by itself. The first is a theoretical one. It is not mathematically possible to maximize for two (or more) variables at the same time. This was clearly stated by von Neumann and Morgenstern, [3] but the principle is implicit in the theory of partial differential equations, dating back at least to D'Alembert (1717-1783).

The second reason springs directly from biological facts. To live, any organism must have a source of energy (for example, food). This energy is utilized for two purposes: mere maintenance and work. For man maintenance of life requires about 1600 kilocalories a day ("maintenance calories"). Anything that he does over and above merely staying alive will be defined as work, and is supported by "work calories" which he takes in. Work calories are used not only for what we call work in common speech; they are also required for all forms of enjoyment, from swimming and automobile racing to playing music and writing poetry. If our goal is to maximize population it is obvious what we must do: We must make the work calories per person approach as close to zero as possible. No gourmet meals, no vacations, no sports, no music, no literature, no art… I think that everyone will grant, without argument or proof, that maximizing population does not maximize goods. Bentham's goal is impossible.

In reaching this conclusion I have made the usual assumption that it is the acquisition of energy that is the problem. The appearance of atomic energy has led some to question this assumption. However, given an infinite source of energy, population growth still produces an inescapable problem. The problem of the acquisition of energy is replaced by the problem of its dissipation, as J. H. Fremlin has so wittily shown. [4] The arithmetic signs in the analysis are, as it were, reversed; but Bentham's goal is unobtainable.

The optimum population is, then, less than the maximum. The difficulty of defining the optimum is enormous; so far as I know, no one has seriously tackled this problem. Reaching an acceptable and stable solution will surely require more than one generation of hard analytical work -- and much persuasion.

We want the maximum good per person; but what is good? To one person it is wilderness, to another it is ski lodges for thousands. To one it is estuaries to nourish ducks for hunters to shoot; to another it is factory land. Comparing one good with another is, we usually say, impossible because goods are incommensurable. Incommensurables cannot be compared.

Theoretically this may be true; but in real life incommensurables are commensurable. Only a criterion of judgment and a system of weighting are needed. In nature the criterion is survival. Is it better for a species to be small and hideable, or large and powerful? Natural selection commensurate the incommensurables. The compromise achieved depends on a natural weighting of the values of the variables.

Man must imitate this process. There is no doubt that in fact he already does, but unconsciously. It is when the hidden decisions are made explicit that the arguments begin. The problem for the years ahead is to work out an acceptable theory of weighting. Synergistic effects, nonlinear variation, and difficulties in discounting the future make the intellectual problem difficult, but not (in principle) insoluble.

Has any cultural group solved this practical problem at the present time, even on an intuitive level? One simple fact proves that none has: there is no prosperous population in the world today that has, and has had for some time, a growth rate of zero. Any people that has intuitively identified its optimum point will soon reach it, after which its growth rate becomes and remains zero.

Of course, a positive growth rate might be taken as evidence that a population is below its optimum. However, by any reasonable standards, the most rapidly growing populations on earth today are (in general) the most miserable. This association (which need not be invariable) casts doubt on the optimistic assumption that the positive growth rate of a population is evidence that it has yet to reach its optimum.

We can make little progress in working toward optimum population size until we explicitly exorcise the spirit of Adam Smith in the field of practical demography. In economic affairs, The Wealth of Nations (1776) popularized the "invisible hand," the idea that an individual who "intends only his own gain," is, as it were, "led by an invisible hand to promote…the public interest." [5] Adam Smith did not assert that this was invariably true, and perhaps neither did any of his followers. But he contributed to a dominant tendency of thought that has ever since interfered with positive action based on rational analysis, namely, the tendency to assume that decisions reached individually will, in fact, be the best decisions for an entire society. If this assumption is correct it justifies the continuance of our present policy of laissez faire in reproduction. If it is correct we can assume that men will control their individual fecundity so as to produce the optimum population. If the assumption is not correct, we need to reexamine our individual freedoms to see which ones are defensible.

Tragedy of Freedom in a Commons

The rebuttal to the invisible hand in population control is to be found in a scenario first sketched in a little-known Pamphlet in 1833 by a mathematical amateur named William Forster Lloyd (1794-1852). [6] We may well call it "the tragedy of the commons," using the word "tragedy" as the philosopher Whitehead used it [7]: "The essence of dramatic tragedy is not unhappiness. It resides in the solemnity of the remorseless working of things." He then goes on to say, "This inevitableness of destiny can only be illustrated in terms of human life by incidents which in fact involve unhappiness. For it is only by them that the futility of escape can be made evident in the drama."

The tragedy of the commons develops in this way. Picture a pasture open to all. It is to be expected that each herdsman will try to keep as many cattle as possible on the commons. Such an arrangement may work reasonably satisfactorily for centuries because tribal wars, poaching, and disease keep the numbers of both man and beast well below the carrying capacity of the land. Finally, however, comes the day of reckoning, that is, the day when the long-desired goal of social stability becomes a reality. At this point, the inherent logic of the commons remorselessly generates tragedy.

As a rational being, each herdsman seeks to maximize his gain. Explicitly or implicitly, more or less consciously, he asks, " What is the utility to me of adding one more animal to my herd?" This utility has one negative and one positive component.

1. The positive component is a function of the increment of one animal. Since the herdsman receives all the proceeds from the sale of the additional animal, the positive utility is nearly + 1.

2. The negative component is a function of the additional overgrazing created by one more animal. Since, however, the effects of overgrazing are shared by all the herdsmen, the negative utility for any particular decision-making herdsman is only a fraction of - 1.

Adding together the component partial utilities, the rational herdsman concludes that the only sensible course for him to pursue is to add another animal to his herd. And another.... But this is the conclusion reached by each and every rational herdsman sharing a commons. Therein is the tragedy. Each man is locked into a system that compels him to increase his herd without limit -- in a world that is limited. Ruin is the destination toward which all men rush, each pursuing his own best interest in a society that believes in the freedom of the commons. Freedom in a commons brings ruin to all.

Some would say that this is a platitude. Would that it were! In a sense, it was learned thousands of years ago, but natural selection favors the forces of psychological denial. [8] The individual benefits as an individual from his ability to deny the truth even though society as a whole, of which he is a part, suffers. Education can counteract the natural tendency to do the wrong thing, but the inexorable succession of generations requires that the basis for this knowledge be constantly refreshed.

A simple incident that occurred a few years ago in Leominster, Massachusetts shows how perishable the knowledge is. During the Christmas shopping season the parking meters downtown were covered with plastic bags that bore tags reading: "Do not open until after Christmas. Free parking courtesy of the mayor and city council." In other words, facing the prospect of an increased demand for already scarce space, the city fathers reinstituted the system of the commons. (Cynically, we suspect that they gained more votes than they lost by this retrogressive act.)

In an approximate way, the logic of the commons has been understood for a long time, perhaps since the discovery of agriculture or the invention of private property in real estate. But it is understood mostly only in special cases which are not sufficiently generalized. Even at this late date, cattlemen leasing national land on the Western ranges demonstrate no more than an ambivalent understanding, in constantly pressuring federal authorities to increase the head count to the point where overgrazing produces erosion and weed-dominance. Likewise, the oceans of the world continue to suffer from the survival of the philosophy of the commons. Maritime nations still respond automatically to the shibboleth of the "freedom of the seas." Professing to believe in the "inexhaustible resources of the oceans," they bring species after species of fish and whales closer to extinction. [9]

The National Parks present another instance of the working out of the tragedy of the commons. At present, they are open to all, without limit. The parks themselves are limited in extent -- there is only one Yosemite Valley -- whereas population seems to grow without limit. The values that visitors seek in the parks are steadily eroded. Plainly, we must soon cease to treat the parks as commons or they will be of no value to anyone.

What shall we do? We have several options. We might sell them off as private property. We might keep them as public property, but allocate the right to enter them. The allocation might be on the basis of wealth, by the use of an auction system. It might be on the basis of merit, as defined by some agreed­upon standards. It might be by lottery. Or it might be on a first-come, first-served basis, administered to long queues. These, I think, are all objectionable. But we must choose -- or acquiesce in the destruction of the commons that we call our National Parks.


In a reverse way, the tragedy of the commons reappears in problems of pollution. Here it is not a question of taking something out of the commons, but of putting something in -- sewage, or chemical, radioactive, and heat wastes into water; noxious and dangerous fumes into the air; and distracting and unpleasant advertising signs into the line of sight. The calculations of utility are much the same as before. The rational man finds that his share of the cost of the wastes he discharges into the commons is less than the cost of purifying his wastes before releasing them. Since this is true for everyone, we are locked into a system of "fouling our own nest," so long as we behave only as independent, rational, free enterprisers.

The tragedy of the commons as a food basket is averted by private property, or something formally like it. But the air and waters surrounding us cannot readily be fenced, and so the tragedy of the commons as a cesspool must be prevented by different means, by coercive laws or taxing devices that make it cheaper for the polluter to treat his pollutants than to discharge them untreated. We have not progressed as far with the solution of this problem as we have with the first. Indeed, our particular concept of private property, which deters us from exhausting the positive resources of the earth, favors pollution. The owner of a factory on the bank of a stream -- whose property extends to the middle of the stream -- often has difficulty seeing why it is not his natural right to muddy the waters flowing past his door. The law, always behind the times, requires elaborate stitching and fitting to adapt it to this newly perceived aspect of the commons.

The pollution problem is a consequence of population. It did not much matter how a lonely American frontiersman disposed of his waste. "Flowing water purifies itself every ten miles," my grandfather used to say, and the myth was near enough to the truth when he was a boy, for there were not too many people. But as population became denser, the natural chemical and biological recycling processes became overloaded, calling for a redefinition of property rights.

How to Legislate Temperance?

Analysis of the pollution problem as a function of population density uncovers a not generally recognized principle of morality, namely: the morality of an act is a function of the state of the system at the time it is performed. [10] Using the commons as a cesspool does not harm the general public under frontier conditions, because there is no public; the same behavior in a metropolis is unbearable. A hundred and fifty years ago a plainsman could kill an American bison, cut out only the tongue for his dinner, and discard the rest of the animal. He was not in any important sense being wasteful. Today, with only a few thousand bison left, we would be appalled at such behavior.

In passing, it is worth noting that the morality of an act cannot be determined from a photograph. One does not know whether a man killing an elephant or setting fire to the grassland is harming others until one knows the total system in which his act appears. "One picture is worth a thousand words," said an ancient Chinese; but it may take ten thousand words to validate it. It is as tempting to ecologists as it is to reformers in general to try to persuade others by way of the photographic shortcut. But the essence of an argument cannot be photographed: it must be presented rationally -- in words.

That morality is system-sensitive escaped the attention of most codifiers of ethics in the past. "Thou shalt not…" is the form of traditional ethical directives which make no allowance for particular circumstances. The laws of our society follow the pattern of ancient ethics, and therefore are poorly suited to governing a complex, crowded, changeable world. Our epicyclic solution is to augment statutory law with administrative law. Since it is practically impossible to spell out all the conditions under which it is safe to burn trash in the back yard or to run an automobile without smog control, by law we delegate the details to bureaus. The result is administrative law, which is rightly feared for an ancient reason -- Quis custodies ipsos custodes? -- Who shall watch the watchers themselves? John Adams said that we must have a "government of laws and not men." Bureau administrators, trying to evaluate the morality of acts in the total system, are singularly liable to corruption, producing a government by men, not laws.

Prohibition is easy to legislate (though not necessarily to enforce); but how do we legislate temperance? Experience indicates that it can be accomplished best through the mediation of administrative law. We limit possibilities unnecessarily if we suppose that the sentiment of Quis custodiet denies us the use of administrative law. We should rather retain the phrase as a perpetual reminder of fearful dangers we cannot avoid. The great challenge facing us now is to invent the corrective feedbacks that are needed to keep custodians honest. We must find ways to legitimate the needed authority of both the custodians and the corrective feedbacks.

Freedom to Breed Is Intolerable

The tragedy of the commons is involved in population problems in another way. In a world governed solely by the principle of "dog eat dog" -- if indeed there ever was such a world -- how many children a family had would not be a matter of public concern. Parents who bred too exuberantly would leave fewer descendants, not more, because they would be unable to care adequately for their children. David Lack and others have found that such a negative feedback demonstrably controls the fecundity of birds. [11] But men are not birds, and have not acted like them for millenniums, at least.

If each human family were dependent only on its own resources; if the children of improvident parents starved to death; if thus, over breeding brought its own "punishment " to the germ line -- then there would be no public interest in controlling the breeding of families. But our society is deeply committed to the welfare state, [12] and hence is confronted with another aspect of the tragedy of the commons.

In a welfare state, how shall we deal with the family, the religion, the race, or the class (or indeed any distinguishable and cohesive group) that adopts over breeding as a policy to secure its own aggrandizement? [13] To couple the concept of freedom to breed with the belief that everyone born has an equal right to the commons is to lock the world into a tragic course of action.

Unfortunately this is just the course of action that is being pursued by the United Nations. In late 1967, some thirty nations agreed to the following: "The Universal Declaration of Human Rights describes the family as the natural and fundamental unit of society. It follows that any choice and decision with regard to the size of the family must irrevocably rest with the family itself, and cannot be made by anyone else.” [14]

It is painful to have to deny categorically the validity of this right; denying it, one feels as uncomfortable as a resident of Salem, Massachusetts, who denied the reality of witches in the seventeenth century. At the present time, in liberal quarters, something like a taboo acts to inhibit criticism of the United Nations. There is a feeling that the United Nations is "our last and best hope," that we shouldn't find fault with it; we shouldn't play into the hands of the archconservatives. However, let us not forget what Robert Louis Stevenson said: "The truth that is suppressed by friends is the readiest weapon of the enemy." If we love the truth we must openly deny the validity of the Universal Declaration of Human Rights, even though it is promoted by the United Nations. We should also join with Kingsley Davis [15] in attempting to get Planned Parenthood-World Population to see the error of its ways in embracing the same tragic ideal.

Conscience Is Self-Eliminating

It is a mistake to think that we can control the breeding of mankind in the long run by an appeal to conscience. Charles Galton Darwin made this point when he spoke on the centennial of the publication of his grandfather's great book. The argument is straightforward and Darwinian.

People vary. Confronted with appeals to limit breeding, some people will undoubtedly respond to the plea more than others. Those who have more children will produce a larger fraction of the next generation than those with more susceptible consciences. The differences will be accentuated, generation by generation.

In C. G. Darwin's words: "It may well be that it would take hundreds of generations for the progenitive instinct to develop in this way, but if it should do so, nature would have taken her revenge, and the variety Homo contracipiens would become extinct and would be replaced by the variety Homo progenitivus.[16]

The argument assumes that conscience or the desire for children (no matter which) is hereditary-but hereditary only in the most general formal sense. The result will be the same whether the attitude is transmitted through germ cells, or exosomatically, to use A. J. Lotka's term. (If one denies the latter possibility as well as the former, then what's the point of education?) The argument has here been stated in the context of the population problem, but it applies equally well to any instance in which society appeals to an individual exploiting a commons to restrain himself for the general good -- by means of his conscience. To make such an appeal is to set up a selective system that works toward the elimination of conscience from the race.

Pathogenic Effects of Conscience

The long-term disadvantage of an appeal to conscience should be enough to condemn it; but it has serious short-term disadvantages as well. If we ask a man who is exploiting a commons to desist "in the name of conscience," what are we saying to him? What does he hear? -- not only at the moment but also in the wee small hours of the night when, half asleep, he remembers not merely the words we used but also the nonverbal communication cues we gave him unawares? Sooner or later, consciously or subconsciously, he senses that he has received two communications, and that they are contradictory: 1. (intended communication) "If you don't do as we ask, we will openly condemn you for not acting like a responsible citizen"; 2. (the unintended communication) "If you do behave as we ask, we will secretly condemn you for a simpleton who can be shamed into standing aside while the rest of us exploit the commons."

Every man then is caught in what Bateson has called a "double bind." Bateson and his co-workers have made a plausible case for viewing the double bind as an important causative factor in the genesis of schizophrenia. [17] The double bind may not always be so damaging, but it always endangers the mental health of anyone to whom it is applied. "A bad conscience," said Nietzsche, "is a kind of illness."

To conjure up a conscience in others is tempting to anyone who wishes to extend his control beyond the legal limits. Leaders at the highest level succumb to this temptation. Has any president during the past generation failed to call on labor unions to moderate voluntarily their demands for higher wages, or to steel companies to honor voluntary guidelines on prices? I can recall none. The rhetoric used on such occasions is designed to produce feelings of guilt in noncooperators.

For centuries it was assumed without proof that guilt was a valuable, perhaps even an indispensable, ingredient of the civilized life. Now, in this post-Freudian world, we doubt it.

Paul Goodman speaks from the modern point of view when he says: "No good has ever come from feeling guilty, neither intelligence, policy, nor compassion. The guilty do not pay attention to the object but only to themselves, and not even to their own interests, which might make sense, but to their anxieties.” [18]

One does not have to be a professional psychiatrist to see the consequences of anxiety. We in the Western world are just emerging from a dreadful two centuries-long Dark Ages of Eros that was sustained partly by prohibition laws, but perhaps more effectively by the anxiety-generating mechanisms of education. Alex Comfort has told the story well in The Anxiety Makers; [19] it is not a pretty one.

Since proof is difficult, we may even concede that the results of anxiety may sometimes, from certain points of view, be desirable. The larger question we should ask is whether, as a matter of policy, we should ever encourage the use of a technique the tendency (if not the intention) of which is psychologically pathogenic. We hear much talk these days of responsible parenthood; the coupled words are incorporated into the titles of some organizations devoted to birth control. Some people have proposed massive propaganda campaigns to instill responsibility into the nation's (or the world's) breeders. But what is the meaning of the word conscience? When we use the word responsibility in the absence of substantial sanctions are we not trying to browbeat a free man in a commons into acting against his own interest? Responsibility is a verbal counterfeit for a substantial quid pro quo. It is an attempt to get something for nothing.

If the word responsibility is to be used at all, I suggest that it be in the sense Charles Frankel uses it. [20] "Responsibility," says this philosopher, "is the product of definite social arrangements." Notice that Frankel calls for social arrangements -- not propaganda.

Mutual Coercion Mutually Agreed Upon

The social arrangements that produce responsibility are arrangements that create coercion, of some sort. Consider bank robbing. The man who takes money from a bank acts as if the bank were a commons. How do we prevent such action? Certainly not by trying to control his behavior solely by a verbal appeal to his sense of responsibility. Rather than rely on propaganda we follow Frankel's lead and insist that a bank is not a commons; we seek the definite social arrangements that will keep it from becoming a commons. That we thereby infringe on the freedom of would-be robbers we neither deny nor regret.

The morality of bank robbing is particularly easy to understand because we accept complete prohibition of this activity. We are willing to say "Thou shalt not rob banks," without providing for exceptions. But temperance also can be created by coercion. Taxing is a good coercive device. To keep downtown shoppers temperate in their use of parking space we introduce parking meters for short periods, and traffic fines for longer ones. We need not actually forbid a citizen to park as long as he wants to; we need merely make it increasingly expensive for him to do so. Not prohibition, but carefully biased options are what we offer him. A Madison Avenue man might call this persuasion; I prefer the greater candor of the word coercion.

Coercion is a dirty word to most liberals now, but it need not forever be so. As with the four-letter words, its dirtiness can be cleansed away by exposure to the light, by saying it over and over without apology or embarrassment. To many, the word coercion implies arbitrary decisions of distant and irresponsible bureaucrats; but this is not a necessary part of its meaning. The only kind of coercion I recommend is mutual coercion, mutually agreed upon by the majority of the people affected.

To say that we mutually agree to coercion is not to say that we are required to enjoy it, or even to pretend we enjoy it. Who enjoys taxes? We all grumble about them. But we accept compulsory taxes because we recognize that voluntary taxes would favor the conscienceless. We institute and (grumblingly) support taxes and other coercive devices to escape the horror of the commons.

An alternative to the commons need not be perfectly just to be preferable. With real estate and other material goods, the alternative we have chosen is the institution of private property coupled with legal inheritance. Is this system perfectly just? As a genetically trained biologist I deny that it is. It seems to me that, if there are to be differences in individual inheritance, legal possession should be perfectly correlated with biological inheritance-that those who are biologically more fit to be the custodians of property and power should legally inherit more. But genetic recombination continually makes a mockery of the doctrine of "like father, like son" implicit in our laws of legal inheritance. An idiot can inherit millions, and a trust fund can keep his estate intact. We must admit that our legal system of private property plus inheritance is unjust -- but we put up with it because we are not convinced, at the moment, that anyone has invented a better system. The alternative of the commons is too horrifying to contemplate. Injustice is preferable to total ruin.

It is one of the peculiarities of the warfare between reform and the status quo that it is thoughtlessly governed by a double standard. Whenever a reform measure is proposed it is often defeated when its opponents triumphantly discover a flaw in it. As Kingsley Davis has pointed out, [21] worshipers of the status quo sometimes imply that no reform is possible without unanimous agreement, an implication contrary to historical fact. As nearly as I can make out, automatic rejection of proposed reforms is based on one of two unconscious assumptions: (1) that the status quo is perfect; or (2) that the choice we face is between reform and no action; if the proposed reform is imperfect, we presumably should take no action at all, while we wait for a perfect proposal.

But we can never do nothing. That which we have done for thousands of years is also action. It also produces evils. Once we are aware that the status quo is action, we can then compare its discoverable advantages and disadvantages with the predicted advantages and disadvantages of the proposed reform, discounting as best we can for our lack of experience. On the basis of such a comparison, we can make a rational decision which will not involve the unworkable assumption that only perfect systems are tolerable.

Recognition of Necessity

Perhaps the simplest summary of this analysis of man’s population problems is this: the commons, if justifiable at all, is justifiable only under conditions of low-population density. As the human population has increased, the commons has had to be abandoned in one aspect after another.

First we abandoned the commons in food gathering, enclosing farm land and restricting pastures and hunting and fishing areas. These restrictions are still not complete throughout the world.

Somewhat later we saw that the commons as a place for waste disposal would also have to be abandoned. Restrictions on the disposal of domestic sewage are widely accepted in the Western world; we are still struggling to close the commons to pollution by automobiles, factories, insecticide sprayers, fertilizing operations, and atomic energy installations.

In a still more embryonic state is our recognition of the evils of the commons in matters of pleasure. There is almost no restriction on the propagation of sound waves in the public medium. The shopping public is assaulted with mindless music, without its consent. Our government has paid out billions of dollars to create a supersonic transport which would disturb 50,000 people for every one person whisked from coast to coast 3 hours faster. Advertisers muddy the airwaves of radio and television and pollute the view of travelers. We are a long way from outlawing the commons in matters of pleasure. Is this because our Puritan inheritance makes us view pleasure as something of a sin, and pain (that is, the pollution of advertising) as the sign of virtue?

Every new enclosure of the commons involves the infringement of somebody's personal liberty. Infringements made in the distant past are accepted because no contemporary complains of a loss. It is the newly proposed infringements that we vigorously oppose; cries of "rights" and "freedom" fill the air. But what does "freedom" mean? When men mutually agreed to pass laws against robbing, mankind became more free, not less so. Individuals locked into the logic of the commons are free only to bring on universal ruin; once they see the necessity of mutual coercion, they become free to pursue other goals. I believe it was Hegel who said, "Freedom is the recognition of necessity."

The most important aspect of necessity that we must now recognize, is the necessity of abandoning the commons in breeding. No technical solution can rescue us from the misery of overpopulation. Freedom to breed will bring ruin to all. At the moment, to avoid hard decisions many of us are tempted to propagandize for conscience and responsible parenthood. The temptation must be resisted, because an appeal to independently acting consciences selects for the disappearance of all conscience in the long run, and an increase in anxiety in the short.

The only way we can preserve and nurture other and more precious freedoms is by relinquishing the freedom to breed, and that very soon. "Freedom is the recognition of necessity" -- and it is the role of education to reveal to all the necessity of abandoning the freedom to breed. Only so, can we put an end to this aspect of the tragedy of the commons.


1. J. B. Wiesner and H. F. York, Scientific American 211 (No. 4), 27 (1964).

2. G. Hardin, Journal of Heredity 50,68 (1959), S. von Hoernor, Science 137, 18, (1962).

3. J. von Neumann and O. Morgenstern, Theory of Games and Economic Behavior (Princeton University Press, Princeton, N.J., 1947), p. 11.

4. J. H. Fremlin, New Scientist, No.415 (1964), p. 285.

5. A. Smith, The Wealth of Nations(Modern Library, New York, 1937), p. 423.

6. W. F. Lloyd, Two Lectures on the Checks to Population (Oxford University Press, Oxford, England,1833).

7. A. N. Whitehead, Science and the Modern World (Mentor, New York, 1948), p. 17.

8. G. Hardin, Ed., Population, Evolution, and Birth Control (Freeman, San Francisco, 1964), p. 56.

9. S. McVay, Scientific American 216(No. 8), 13 (1966).

10. J. Fletcher, Situation Ethics(Westminster, Philadelphia, 1966).

11. D. Lack, The Natural Regulation of Animal Numbers (Clarendon Press, Oxford, England, 1954).

12. H. Girvetz, From Wealth to Welfare(Stanford University Press, Stanford, Calif, 1950).

13. G. Hardin, Perspectives in Biology and Medicine 6, 366 (1963).

14. U Thant, International Planned Parenthood News, No. 168 (February 1968), p. 3.

15. K. Davis, Science 158, 730(1967).

16. S. Tax, Ed., Evolution After Darwin (University of Chicago Press, Chicago, 1960), vol. 2, p. 469.

17. G. Bateson, D. D. Jackson, J. Haley, J. Weakland, Behavioral Science 1, 251 (1956).

18. P. Goodman, New York Review of Books10 (8), 22 (23 May 1968).

19. A. Comfort, The Anxiety Makers(Nelson, London, 1967).

20. C. Frankel, The Case for Modern Man (Harper & Row, New York, 1955), p. 203.

21. J. D. Roslansky, Genetics and the Future of Man (Appleton-Century-Crofts, New York, 1966), p.177.

Garrett Hardin was born in Dallas, Texas in 1915. He attended the University of Chicago and went on to earn doctorate in biology from Stanford University in 1941. In 1946 he became a professor of human ecology at the University of California at Santa Barbara. Originally a plant biologist, he became increasingly interested in genetics, evolution, and the problems of pollution and population growth. He campaigned for legalized abortion during the 1960s, was director of the American Eugenics Society in 1971-74, and president of the Environmental Fund in 1980-81. He was the author of several books about human population explosion and father of four children. Garrett Hardin and his wife Jane committed suicide on September 14, 2003.

Garrett Hardin Society.


"It is an act of true moral cowardice to allow children to be born with known genetic defects." - James Watson, the first director of the
Human Genome Project

Race Australian Aboriginals Blacks U.S. Blacks (80% black, 20% white) U.S. Hispanics U.S. Whites U.S. East Asians Ashkenazi Jews
Mean IQ 64 70 85 89 103 107 117

Richard Lynn, "Eugenics: A Reassessment," in Human Evolution, Behavior, and Intelligence series, edited by Seymour W. Itzkoff, Praeger Press, 2001.

Preimplantation genetic diagnosis.

Canine racism.

Humans as Cancer

by A. Kent MacDougall

When a spot on a person's skin changes color, becomes tough or rough and elevated or ulcerated, bleeds, scales, scabs over and fails to heal, it's time to consult a doctor. For these are early signs of skin cancer.

As seen by astronauts and photographed from space by satellites, millions of manmade patterns on the land surface of Earth resemble nothing so much as the skin conditions of cancer patients. The transformation of the natural contours of the land into the geometric patterns of farm fields, the straightening of meandering rivers into canal-like channels, and the logging of forests into checkerboard clearcuts all have their counterparts in the loss of normal skin markings in cancer victims. Green forests logged into brown scrub and overgrazed grasslands bleached into white wasteland are among the changes in Earth's color. Highways, streets, parking lots and other paved surfaces have toughened Earth's surface, while cities have roughened it. Slag heaps and garbage dumps can be compared to raised skin lesions. Open-pit mines, quarries and bomb craters, including the 30 million left by US forces in Indochina, resemble skin ulcerations. Saline seeps in inappropriately irrigated farm fields look like scaly, festering sores. Signs of bleeding include the discharge of human sewage, factory effluents and acid mine drainage into adjacent waterways, and the erosion of topsoil from deforested hillsides to turn rivers, lakes and coastal waters yellow, brown and red. The red ring around much of Madagascar that is visible from space strikes some observers as a symptom that the island is bleeding to death.

If skin cancer were all that ailed Earth, the planet's eventual recovery would be less in doubt. For with the exception of malignant melanoma, skin cancer is usually curable. But the parallels between the way cancer progresses in the human body and humans' progressively malignant impact on Earth are more than skin-deep. Consider:

Cancer cells proliferate rapidly and uncontrollably in the body; humans continue to proliferate rapidly and uncontrollably in the world. Crowded cancer cells harden into tumors; humans crowd into cities. Cancer cells infiltrate and destroy adjacent normal tissues; urban sprawl devours open land. Malignant tumors shed cells that migrate to distant parts of the body and set up secondary tumors; humans have colonized just about every habitable part of the globe. Cancer cells lose their natural appearance and distinctive functions; humans homogenize diverse natural ecosystems into artificial monocultures. Malignant tumors excrete enzymes and other chemicals that adversely affect remote parts of the body; humans' motor vehicles, power plants, factories and farms emit toxins that pollute environments far from the point of origin.

A cancerous tumor continues to grow even as its expropriation of nutrients and disruption of vital functions cause its host to waste away. Similarly, human societies undermine their own long-term viability by depleting and fouling the environment. With civilization as with cancer, initial success begets self-defeating excess.

It's easy to dismiss the link between cancer the disease in humans and humans as a disease on the planet as both preposterous and repulsive -- or as a mere metaphor rather than the unifying hypothesis its leading proponent claims for it. Only a handful of limited-circulation periodicals, including this one (see Forencich 1992/93), have granted the concept a respectful hearing.

Accepting the humans-as-cancer concept comes easier if one also accepts the Gaia hypothesis that the planet functions as a single living organism. To be sure, the Earth is mostly inanimate. Its rocky, watery surface supports only a relatively thin layer of plants, animals and other living organisms. But so, too, is a mature tree mostly dead wood and bark, with only its thin cambium layer and its leaves, flowers and seeds actually alive. Yet the tree is a living organism. Earth behaves like a living organism to the extent that the chemical composition of its rocky crust, oceans and atmosphere has both supported and been influenced by the biological processes of living organisms over several billion years. These self-sustaining, self-regulating processes have kept the Earth's surface temperature, its concentrations of salt in the oceans and oxygen in the atmosphere, and other conditions favorable for life.

James Lovelock, who propounded the Gaia hypothesis in 1979, initially rejected humans' cancer-like impacts as a corollary, declaring flatly: "People are not in any way like a tumor" (Lovelock 1988, p. 177). But before long he modified this view, observing: "Humans on the Earth behave in some ways like a pathogenic micro-organism, or like the cells of a tumor or neoplasm" (Lovelock 1991,p. 153).

Others have stated the connection more strongly. "If you picture Earth and its inhabitants as a single self-sustaining organism, along the lines of the popular Gaia concept, then we humans might ourselves be seen as pathogenic," Jerold M. Lowenstein, professor of medicine at the University of California, San Francisco, has written. "We are infecting the planet, growing recklessly as cancer cells do, destroying Gaia's other specialized cells (that is, extinguishing other species), and poisoning our air supply....From a Gaian perspective... the main disease to be eliminated is us" (Lowenstein 1992).

Dr. Lowenstein isn't the first physician to examine the planet as a patient and find it afflicted with humanoid cancer. Alan Gregg pioneered the diagnosis. As a long-time official of the Rockefeller Foundation, responsible for recommending financial grants to improve public health and medical education, Dr. Gregg traveled widely in the years following World War II and observed the worldwide population boom. By 1954 he had seen enough. In a brief paper delivered at a symposium and subsequently published in Science, Gregg (1955) compared the world to a living organism and the explosion in human numbers to a proliferation of cancer cells. He sketched other parallels between cancer in humans and humans' cancer-like impact on the world. And he expressed hope -- unrealized to this day -- that "this somewhat bizarre comment on the population problem may point to a new concept of human self-restraint."

It has fallen to a physician who is also an epidemiologist to flesh out and fill in Gregg's sketchily drawn analysis. Warren M. Hern wrote his Ph.D. dissertation on how the intrusion of Western civilization has increased birth rates among Peruvian Amazon Indians. He does his bit to keep the US birth rate down by operating an abortion clinic in Boulder, Colorado. Hern (1990) published a major article that laid out in detail, and buttressed with anthropological, ecological and historical evidence, the ways in which the human species constitutes a "malignant eco-tumor." He proposed renaming us Homo esophagus (for "the man who devours the ecosystem"). Illustrations accompanying the article included aerial photographs of US cities juxtaposed with look-alike photos of brain and lung tumors.

Dr. Hern has delivered papers on the hypothesis at symposia organized by the Population Association of America, the American Association for the Advancement of Science, and the American Public Health Association. Two papers have subsequently been published (Hern 1993a, 1993b). But in general the scientific community doesn't take his hypothesis seriously, preferring to see it as a mere metaphor or analogy. Indeed, it has evoked hostility in some quarters. When Hern presented the hypothesis at the International Conference on Population and Development in Cairo in 1994, listeners reacted angrily, with one threatening, "Are you ready to die?" A Denver radio talk show host called Dr. Hern an "ecoquack" and a "fellow-in-good-standing of the Sky-Is-Falling School."

Such disparagement can be seen as yet another parallel between cancer the scourge in humans and humans as a carcinogenic scourge on the world. For just as Warren Hern encounters indifference, denial and downright hostility to his views, until recently American doctors routinely kept their cancer patients in the dark about the nature of their illness. The aim was to spare patients the shock, fear, anger and depression that the bad news commonly evokes. Families were reluctant to admit that a relative had died of cancer, and newspaper obituaries referred euphemistically to the cause of a death from cancer as "a long illness." In Japan, cancer remains a taboo topic. Public opinion polls indicate that people would rather not know if they have cancer and doctors would rather not tell them. When Emperor Hirohito was dying of cancer of the duodenum, his doctors lied, telling both him and the public that he had "chronic pancreatitis" (Sanger 1989).

In the United States, even some environmentally enlightened analysts remain in denial when it comes to the humans-as-a-planetary-cancer hypothesis. Christopher D. Stone, a law professor at the University of Southern California and son of the late leftist journalist I. F. Stone, authored an influential essay on environmental law, Should Trees Have Standing? Toward Legal Rights for Natural Objects. But in his latest book Stone (1993, p.4) casts doubt on the proposition that "the earth has cancer, and the cancer is man." "The interdependency of the earth's parts does not amount to the interdependency of organs within a true organism," he notes. "The earth as a whole, including its life web, is not as fragile...the Gaian relationships are not so finely, so precariously tuned."

Even deep ecologists acknowledge that Earth is qualitatively different from a true organism, that its legitimate status as a superecosystem falls short of qualifying it as a superorganism. Frank Forencich, who argued in "Homo Carcinomicus: A Look at Planetary Oncology" (Forencich 1992/93) that "the parallels between neoplastic growth and human population are astonishing," concedes that even a nuclear winter wouldn't completely destroy the living biosphere, much less the inanimate lithosphere, hydrosphere and atmosphere. "We can't kill the host," he says. "Civilization will break up before the biosphere goes" (Forencich 1993).

Still another objection is that any generalization about cancer is suspect because cancer is not a single disease, but rather a group of more than 100 diseases that differ as to cause and characteristics. Some cancers -- breast cancer, for instance -- typically grow rapidly and spread aggressively. Others, such as cancers of the small intestine, usually grow slowly. Prostate cancer often grows so slowly that it causes no problem. "It's completely possible for an organism to have cancer cells for its entire lifetime and suffer no ill effects" (Garrett 1988, p.43).

The lack of a perfect correspondence between cancer the disease in humans and humans' cancer-like effects on the Earth invalidates the humans-as-cancer concept for some observers. But Warren Hern insists humans-as-cancer is a hypothesis because it is subject to verification or refutation and because it is useful as a basis for further investigation. Frank Forencich, in contrast, is content to consider the concept a metaphor. "That humans are like cancer is indisputable," he says. "But humans are not cancer itself."

Whether as metaphor or hypothesis, the proposition that humans have been acting like malignant cancer cells deserves to be taken seriously. The proposition offers a unifying interpretation of such seemingly unconnected phenomena as the destruction of ecosystems, the decay of inner cities and the globalization of Western commodity culture. It provides a valuable macrocosmic perspective on human impacts, as well as a revealing historic perspective in tracing humans' carcinogenic propensities back to the earliest times.

The progenitors of modern humans exhibited one of cancer cells' most significant characteristics, loss of adhesion, one to two million years ago. Because cancer cells are attached more loosely to one another than normal cells are, they separate easily, move randomly and invade tissues beyond those from which they were derived. Our direct ancestors, Homo erectus, demonstrated this trait in migrating out of Africa. Living in small mobile groups, these foragers/scavengers/hunters spread across Asia and Europe. The next hominid species in the evolutionary line, Homo sapiens, extended the dispersal into previously uninhabitable northern forests and tundra. Their successors, anatomically modern Homo sapiens sapiens, have spread to every continent and major ice-free island. With the aid of clothing, shelter, technology and imported supplies, they now occupy forests, wetlands, deserts, tundra and other areas formerly considered too wet, too dry, too cold, or too remote for human habitation. Humans now occupy, or have altered and exploited, two-thirds to nine-tenths (estimates vary) of the planet's land surface. It seems only a matter of time before they take over all the remaining "empty" spaces.

Humans' ongoing expropriation of the planet has proceeded apace with the eruption of human numbers; and the eruption of human numbers has features in common with the proliferation of cancer cells. In a healthy body, genetic controls enable a large number of individual cells to live together harmoniously as a single organism. Genetic switches signal normal cells when it is time to divide and multiply, and when it is time to break apart and be absorbed by neighboring cells. When the genetic switches are damaged, as by chemicals, radiation, or viruses, they can get locked in the "on" position. This turns normal cells into malignant cells that divide and multiply in disregard of the health of the entire organism.

When humans lived in semi-nomadic bands in harmony with an environment they did not dominate, they limited their numbers so as not to exceed the supply of food they could gather, scavenge, and hunt. Nor did they produce more young than they could carry between seasonal camps. Their contraceptive measures included coitus interruptus (withdrawal), pessaries, and prolonged breastfeeding to depress the hormones that trigger ovulation. When these methods failed, they resorted to abortion and infanticide. Like normal cells in a healthy body, hunter-gatherers seemed to know when to stop growing.

However, technological and cultural contaminants upset this delicate natural balance, permitting humans to multiply beyond numbers compatible with the harmonious health of the global ecosystem. The first and still the foremost contaminant was fire. By 400,000 years ago -- perhaps even earlier -- hunter-gatherers had learned to control and use fire. Thus began the transformation of humans from just another large mammal in competition with other fierce predators into the undisputed overlord of all species, plant and animal. Addiction to combustion has defined human existence ever since, and has escalated into the current orgy of fossil-fuel burning with the potential of overheating Gaia and jeopardizing the existence of all her inhabitants.

Fire was generally benign when used by hunter-gatherers to thin dense forests into more open and park-like landscapes supporting more game. But the increase in food supply that more effective hunting and the cooking of tough meat and fibrous vegetable matter made possible swelled hunter-gatherer populations. As humans proliferated and spread out, overhunted and overgathered, large game and suitable wild foods became less abundant. This made hunting and gathering less efficient, leaving horticulture, which previously hadn't been worth the extra effort, as the only viable alternative.

Clearing forests to farm began some 10,000 years ago in Asia Minor. About 2000 years later, shifting horticulturists began slashing and burning their way northwestward across Europe. They overwhelmed and pushed aside less numerous hunter-gatherers before giving way in turn to agriculturalists whose plow cultivation of permanent fields permitted more intensive food production and denser populations.

Agriculture condemned peasants to a short, harsh life of monotonous toil, an inadequate diet, the constant threat of crop failure and starvation and exposure to virulent contagious diseases. It fostered social stratification and sexual inequality, cruel treatment of animals, despotism and warfare. And it encouraged further cancer-like encroachment on wilderness to feed increased populations and to replace fields and pastures eroded and depleted of soil fertility by overcropping and overgrazing. The elites that came to dominate sedentary agrarian societies caused still more woodland to be cleared and marshland to be drained to maximize production they could expropriate for their own use. This economic surplus, in turn, helped support an increasing concentration of people in river valleys, along seacoasts, and in cities.

The massing of humans into cities is all too similar to the way crowded cancer cells harden into tumors. Whereas normal cells in a tissue culture stop reproducing when they come in contact with other cells, cancer cells continue to divide and pile up on top of one another, forming clumps. Normal cells display contact inhibition, growing only to the limits of their defined space and then stopping. Cancer cells never know when to quit.

Likewise, human populations grow even under extremely crowded conditions. The very essence of civilization is the concentration of people in cities. As scattered farming villages evolved into towns, and some towns became trading, manufacturing, ceremonial and administrative centers, the city was born. Fed by grain grown in the provinces and served by slaves seized there, the administrative centers of empires grew large; Rome may have reached one million people at its height in 100 C.E. Yet not until industrialization and the extensive exploitation of distant resources after 1800 did cities really begin getting out of hand, and in 1900, still only one in ten people lived in cities. Half will in 2000, with 20 metropolitan areas expected to have 10 million or more people each.

The propensity of modern cities to spread out over the countryside -- absorbing villages, destroying farm fields, filling in open land, and creating vast new agglomerations -- was noted early in this century by the Scottish garden-city planner Patrick Geddes. Geddes (1915) identified half a dozen such "conurbations" in the making in Britain, and he foresaw the approach of a 500-mile megalopolis along the northern Atlantic seaboard in the United States. Geddes compared urban sprawl to an amoeba, but it fell to his American protege Lewis Mumford to liken disorderly, shapeless, uncoordinated urban expansion to a malignant tumor, observing that "the city continues to grow inorganically, indeed cancerously, by a continuous breaking down of old tissues, and an overgrowth of formless new tissue" (Mumford 1961, p. 543).

A malignant tumor develops its own blood vessels as it grows. Similarly, cities vascularize with aqueducts, electric power lines, highways, railroads, canals and other conduits. A tumor uses its circulation network to pirate nutrients from the body. Similarly, cities parasitically tap the countryside and beyond to bring in food, fuel, water, and other supplies. However, just as a tumor eventually outgrows its blood supply, causing a part of it, often at the center, to die, inner city neighborhoods and even older suburbs often atrophy. Alan Gregg (1955) noted this parallel 40 years ago, observing "how nearly the slums of our great cities resemble the necrosis of tumors."

Humans are increasingly concentrated along seacoasts. Sixty percent of the world's people now live within 100 kilometers of a seacoast. In Australia, one of the world's most highly urbanized nations, nine of every ten people live along the coast. The boom in international trade, from which coastal areas receive a disproportionate share of the benefits, helps explain the worldwide trend; but the pattern goes back thousands of years and parallels yet another carcinogenic process: metastasis.

In metastasis, a tumor sheds cancer cells that then migrate to distant sites of the body and set up secondary growths. The medium for the migration of the cells is the blood and lymphatic systems. In the ancient world of the Mediterranean, another fluid -- water -- facilitated the migration of people and goods. The Phoenicians, Greeks, Carthagenians and Romans all took advantage of the relative ease of travel and transport by water to establish colonies all around the Mediterranean. At the height of the Roman Empire, no fewer than 500 settlements flourished along the African coast from Morocco to Egypt.

Just as secondary tumors in the human body destroy the tissues and organs they invade, colonizers of the ancient Mediterranean devastated the fertile but fragile ecosystems of the coastal regions they colonized. They logged coastal forests for ship timbers and building materials, to provide charcoal to fire bricks and pottery and smelt mineral ores, and to create farm fields and pastures. Overcropping, fires, sheep and goats prevented regeneration. Intense winter rains washed the thin, easily eroded soil down hillsides into coastal plains to smother farm fields, choke the mouths of rivers, create malarial marshes, bury port cities and strand many of them miles from the sea. The slopes, left barren, have not recovered to this day.

The voraciousness of secondary tumors as they invade and consume tissues and organs has its counterpart in the orgies of destruction that states and especially empires have engaged in for 5000 years. In many cases, the destruction has exceeded what was in the destroyer's own self-interest. Many invaders routinely obliterated the cities they conquered, massacred their inhabitants, and destroyed their fields and flocks instead of just taking them over. Carpet bombing of cities and the mass slaughter of their civilian noncombatant populations during World War II constitute the modern equivalent. Ancient Romans ransacked their empire for bears, lions, leopards, elephants, rhinos, hippos and other live animals to be tormented and killed in public arenas until there were no more to be found. European invaders of North America and Siberia did in the fur trade from which they so hugely profited by the self-defeating overkill of fur-bearing animals.

Human destruction of ecosystems has increased relentlessly since industrialization. The annihilation of 60 million bison on the North American Great Plains was made possible by the intrusion of railroads and the invention of the repeating rifle. The reckless exploitation of whales was speeded by the invention of the explosive harpoon, cannon-winch and engine-driven ship. Enormous nets towed by today's factory trawlers permit oceans to be strip-mined for fish -- and any other creature unlucky enough to become ensnared in these curtains of death. Tractors and other modern farm machinery alternately compact and pulverize topsoil, increasing its vulnerability to erosive winds and rains. Chain saws and bulldozers level forests faster than axes and hand saws ever could. Dynamite and drag line excavators permit strip mining on a scale hitherto unimaginable, decapitating mountains, turning landscapes into moon craters, and rendering islands such as phosphate-rich Nauru in the South Pacific all but uninhabitable. Boring holes in the earth to get at minerals, of course, resembles the way cancer bores holes in muscle and bone. As Peter Russell (1983, p.33) has observed, "Technological civilization really does look like a rampant malignant growth blindly devouring its own ancestral host in a selfish act of consumption."

Just as a fast-growing tumor steals nutrients from healthy parts of the body to meet its high energy demands, industrial civilization usurps the resources of healthy ecosystems that their natural plant and animal inhabitants depend on for survival. In 1850, humans and their livestock accounted for 5 percent of the total weight of all terrestrial animal life. Today, that portion exceeds 20 percent, and by the year 2030 it could reach 40 percent (Westing 1990, pp. 110-111).

"Never before in the history of the earth has a single species been so widely distributed and monopolized such a large fraction of the energetic resources. An ever diminishing remainder of these limited resources is now being divided among millions of other species. The consequences are predictable: contraction of geographic ranges, reduction of population sizes, and increased probability of extinction for most wild species; expansion of ranges and increased populations of the few species that benefit from human activity; and loss of biological diversity at all scales from local to global" (Brown and Maurer 1989).

Decline in diversity is common to both cancer and civilization. In both cases, heterogeneity gives way to homogeneity, complexity to simplification. Malignant cells fail to develop into specialized cells of the tissues from which they derive. Instead, "undifferentiated, highly malignant cells tend to resemble one another and fetal tissues more than their adult normal counterpart cells" (Ruddon 1987, p.230).

De-differentiation in human societies is at least as old as agriculture and animal husbandry. Farmers have been replacing diverse species of native plants with pure stands of domesticated crops for thousands of years. Instead of the thousands of kinds of plants that pre-agricultural peoples gathered for food, just seven staples -- wheat, rice, maize, potatoes, barley, sweet potato and cassava -- now supply three-quarters of the caloric content of all the world's food crops. The world's astonishing abundance and variety of wildlife is going fast, with many species soon to be seen only in zoos and game parks, their places taken by cattle, sheep, goats, pigs and other domesticated livestock.

Despite their value in providing wildlife habitat, modulating flood waters and filtering out pollutants, more than half of the world's swamps, marshes, bogs, seasonal flood plains and other wetlands have been drained, dredged, filled in, built on or otherwise destroyed. Temperate forests dominated by trees of many species and of all ages are giving way to single species, same-aged conifer plantations supporting far fewer birds and other wildlife. And the tropical forests that harbor more than half of all species on Earth are being mowed down faster than their bewildering biodiversity can be identified, leading some experts to warn that we are causing the greatest mass extinction since the disappearance of the dinosaurs 65 million years ago.

The tendency of civilizations to homogenize and impoverish ecosystems is nowhere clearer than in urban areas. Major cities are becoming indistinguishable from one another in appearance and undifferentiated in function. Central business districts so resemble one another that travelers can be forgiven for forgetting whether they are in Boston, Brussels or Bombay. Shanty cities in poor countries look alike, as do suburbs in rich countries.

As Lewis Mumford pointed out more than 30 years ago, the archetypal suburban refuge in the United States consists of "a multitude of uniform, unidentifiable houses, lined up inflexibly, at uniform distances, on uniform roads, in a treeless communal waste, inhabited by people of the same class, the same income, the same age group, witnessing the same television performances, eating the same tasteless pre-fabricated foods, from the same freezers, conforming in every outward and inward respect to a common mold, manufactured in the central metropolis. Thus the ultimate effect of the suburban escape in our time is, ironically, a low-grade uniform environment from which escape is impossible" (Mumford 1961, p.486).

Globalization of the economy is enclosing the entire world in a single market for machine-made goods that are increasingly standardized whatever their country of origin. Western material values and capitalist commodity culture, led by American television, movies, music, street fashions and fast food, are dominant internationally. Local and regional individuality, along with indigenous cultures, languages and world views, are fading fast.

The decline of natural and cultural diversity is as threatening to the planet as undifferentiated cells are to the cancer patient. Whereas a well-differentiated prostate cancer tends to grow slowly, remain localized and cause no symptoms, a poorly differentiated one often spreads aggressively. Similarly, traditional farmers who keep weeds, pests and plant diseases in check by rotating crops, fertilizing naturally, and maintaining the tilth of the soil don't threaten Earth's health the way single-crop plantations relying on pesticides, synthetic fertilizers and heavy machinery do. Unfortunately, monocultural agriculture is becoming the norm on every continent.

Hemorrhaging is still another symptom of the carcinogenic process. The first sign of cancer is often spontaneous bleeding from a body orifice, discharge from a nipple, or an oozing sore. Vomiting can warn of a brain tumor or leukemia. Signs that Earth, too, has cancer abound. Cities vomit human sewage and industrial wastes into adjacent waterways. Mines and slag heaps ooze mercury, arsenic, cyanide and sulfuric acid. Wells gush, pipelines leak and tankers spill oil. Farm fields discharge topsoil, fertilizers, pesticides and salts to silt up and poison rivers and estuaries. Cattle feedlots add manure. Most serious of all, deforested, eroded hillsides hemorrhage floods of mud.

Fever is another symptom of cancer in both humans and the planet. Cancer patients become fevered because of increased susceptibility to infection caused by a depressed immune system. Chemotherapy and irradiation can also cause fever, as can temperature-elevating substances released by a malignant tumor. Global warming is the planetary counterpart. Waste products released by industry and motor vehicles, deforestation and other feverish human activities pump inordinate quantities of carbon dioxide, nitrous oxide, methane, chlorofluorocarbons and other greenhouse gases into the atmosphere where they trap heat and raise temperatures.

Wasting, or cachexia, is still another sign of advanced cancer. A cancer patient becomes fatigued and weak, losing both appetite and weight as the tumor releases toxic hormones and makes metabolic demands on the body. "Many cancer patients die not of cancer itself, but of progressive malnutrition" (Rosenbaum 1988, p.264). The planetary counterpart includes loss of forests, fisheries, biodiversity, soil, groundwater and biomass.

It's not in a tumor's self-interest to steal nutrients to the point where the host starves to death, for this kills the tumor as well. Yet tumors commonly continue growing until the victim wastes away. A malignant tumor usually goes undetected until the number of cells in it has doubled at least 30 times from a single cell. The number of humans on Earth has already doubled 32 times, reaching that mark in 1978 when world population passed 4.3 billion. Thirty-seven to 40 doublings, at which point a tumor weighs about one kilogram, are usually fatal (Tannock 1992, pp. 157, 175).

Like a smoker who exaggerates the pain of withdrawal and persists because the carcinogenic consequences of his bad habit don't show up for 20 or 30 years, governments generally avoid the painful adjustments needed to prevent social, economic and environmental disasters in the making. "Governments with limited tenure, in the developing as well as in the developed countries, generally respond to immediate political priorities; they tend to defer addressing the longer term issues, preferring instead to provide subsidies, initiate studies, or make piecemeal modifications of policy" (Hillel 1991, p. 273). So it usually takes a crisis, often a catastrophe, before even the most commonsensical action is taken -- and then it is often too late to avoid irreversible ecological damage.

Is the prognosis for the planet as grim as it is for a patient with advanced cancer? Or will infinitely clever but infrequently wise Homo sapiens alter geocidal behaviors in time to avoid global ruin? Even the most pessimistic doomsayers concede that humans have the capacity to arrest Gaia's deteriorating condition. Cancer cells can't think, but humans can. Cancer cells can't know the full extent of the harm they're doing to the organism of which they are a part, whereas humans have the capacity for planetary awareness. Cancer cells can't consciously modify their behavior to spare their host's life and prolong their own, whereas humans can adjust, adapt, innovate, pull back, change course.

Gaia's future, and humans' with it, depends on their doing so.


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A. Kent MacDougall (911 Oxford St., Berkeley CA 94707) is professor emeritus of journalism at the University of California, Berkeley. He completed his 25-year newspaper reporting career in 1987 with a 24,000-word series of articles for the Los Angeles Times on deforestation around the world and through the ages. The series won the Forest History Society's John M. Collier Award for Forest History Journalism.