Unit 12 Four Laws of Ecology (Part II)

Lesson 12 


Four Laws of Ecology (Part II) 


Barry Commoner 


The Third Law of Ecology: Nature Knows Best 


In my experience this principle is likely to encounter considerable resistance, for it appears to contradict a deeply held idea about the unique competence of human beings. One of the most pervasive features of modern technology is the notion that it is intended to "improve on nature"—to provide food, clothing, shelter, and means of communication and expression which are superior to those available to man in nature. Stated baldly, the third law of ecology holds that any major man-made change in a natural system is likely to be detrimental to that system. This is a rather extreme claim; nevertheless I believe it has a good deal of merit if understood in a properly defined context. 


I have found it useful to explain this principle by means of an analogy. Suppose you were to open the back of your watch, close your eyes, and poke a pencil into the exposed works. The almost certain result would be damage to the watch. Nevertheless, this result is not absolutely certain. There is some finite possibility that the watch was out of adjustment and that the random thrust of the pencil happened to make the precise change needed to improve it. However, this outcome is exceedingly improbable. The question at issue is: why? The answer is self-evident: there is a very considerable amount of what technologists now call "research and development" (or, more familiarly, "R & D") behind the watch. This means that over the years numerous watchmakers, each taught by a predecessor, have tried out a huge variety of detailed arrangements of watch works, have discarded those that are not compatible with the over-all operation of the system and retained the better features. In effect, the watch mechanism, as it now exists, represents a very restricted selection, from among an enormous variety of possible arrangements of component parts, of a singular organization of the watch works. Any random change made in the watch is likely to fall into the very large class of inconsistent, or harmful, arrangements which have been tried out in past watch-making experience and discarded. One might say, as a law of watches, that "the watchmaker knows best." 


There is a close, and very meaningful, analogy in biological systems. It is possible to induce a certain range of random, inherited changes in a living thing by treating it with an agent, such as x-irradiation, that increases the frequency of mutations. Generally, exposure to x-rays increases the frequency of all mutations which have been observed, albeit very infrequently, in nature and can therefore be regarded as possible changes. What is significant, for our purpose, is the universal observation that when mutation frequency is enhanced by x-rays or other means, nearly all the mutations are harmful to the organisms and the great majority so damaging as to kill the organism before it is fully formed. 


In other words, like the watch, a living organism that is forced to sustain a random change in its organization is almost certain to be damaged rather than improved. And in both cases, the explanation is the same—a great deal of "R & D." In effect there are some two to three billion years of "R & D" behind every living thing. In that time, a staggering number of new individual living things have been produced, affording in each case the opportunity to try out the suitability of some random genetic change. If the change damages the viability of the organism, it is likely to kill it before the change can be passed on to future generations. In this way, living things accumulate a complex organization of compatible parts; those possible arrangements that are not compatible with the whole are screened out over the long course of evolution. Thus, the structure of a present living thing or the organization of a current natural ecosystem is likely to be "best" in the sense that it has been so heavily screened for disadvantageous components that any new one is very likely to be worse than the present ones. 


This principle is particularly relevant to the field of organic chemistry. Living things are composed of many thousands of different organic compounds, and it is sometimes imagined that at least some of these might be improved upon if they were replaced by some man-made variant of the natural substance. The third law of ecology suggests that the artificial introduction of an organic compound that does not occur in nature, but is man-made and is nevertheless active in a living system, is very likely to be harmful. 


This is due to the fact the varieties of chemical substances actually found in living things are vastly more restricted than the possible varieties. Obviously there are a fantastically large number of protein types that are not made by living cells. And on the basis of the foregoing, one would reason that many of these possible protein types were once formed in some particular living things, found to be harmful, and rejected through the death of the experiment. In the same way, living cells synthesize fatty acids (a type of organic molecule that contains carbon chains of various lengths) with even-numbered carbon chain lengths (i.e., 4, 6, 8, etc., carbons), but no fatty acids with odd-numbered carbon chain lengths. This suggests that the latter have once been tried out and found wanting. Similarly, organic compounds that contain attached nitrogen and oxygen atoms are singularly rare in living things. This should warn us that the artificial introduction of substances of this type would be dangerous. This is indeed the case, for such substances are usually toxic and frequently carcinogenic. And, I would suppose from the fact that DDT is nowhere found in nature, that somewhere, at some time in the past, some unfortunate cell synthesized this molecule—and died. 


One of the striking facts about the chemistry of living systems is that for every organic substance produced by a living organism, there exists, somewhere in nature, an enzyme capable of breaking that substance down. In effect, no organic substance is synthesized unless there is provision for its degradation; recycling is thus enforced. Thus, when a new man-made organic substance is synthesized with a molecular structure that departs significantly from the types which occur in nature, it is probable that no degradative enzyme exists, and the material tends to accumulate. 


Given these considerations, it would be prudent, I believe, to regard every man-made organic chemical not found in nature which has a strong action on any one organism as potentially dangerous to other forms of life. Operationally, this view means that all man-made organic compounds that are at all active biologically ought to be treated as we do drugs, or rather as we should treat them: prudently, cautiously. Such caution or prudence is, of course, impossible when billions of pounds of the substance are produced and broadly disseminated into the ecosystem where it can reach and affect numerous organisms not under our observation. Yet this is precisely what we have done with detergents, insecticides, and herbicides. The often catastrophic results lend considerable force to the view that "Nature knows best." 


The Fourth Law of Ecology: There Is No Such Thing as a Free Lunch 


In my experience, this idea has proven so illuminating for environmental problems that I have borrowed it from its original source, economics. The "law" derives from a story that economists like to tell about an oil-rich potentate who decided that his new wealth needed the guidance of economic science. Accordingly he ordered his advisers, on pain of death, to produce a set of volumes containing all the wisdom of economics. When the tomes arrived, the potentate was impatient and again issued an order—to reduce all the knowledge of economics to a single volume. The story goes on in this vein, as such stories will, until the advisers are required, if they are to survive, to reduce the totality of economics science to a single sentence. This is the origin of the "free lunch" law. 


In ecology, as in economics, the law is intended to warn that every gain is won at some cost. In a way, this ecological law embodies the three previous laws. Because the global ecosystem is a connected whole, in which nothing can be gained or lost and which is not subject to over-all improvement, anything extracted from it by human effort must be replaced. Payment of this price cannot be avoided; it can only be delayed. The present environmental crisis is a warning that we have delayed nearly too long. 


The preceding pages provide a view of the web of life on the earth. An effort has been made to develop this view from available facts, through logical relations, into a set of comprehensive generalizations. In other words, the effort has been scientific. 


Nevertheless, it is difficult to ignore the embarrassing fact that the final generalizations which emerge from all this—the four laws of ecology—are ideas that have been widely held by many people without any scientific analysis or professional authorization. The complex web in which all life is enmeshed, and man's place in it, are clearly—and beautifully—described in poems of Walt Whitman. A great deal about the interplay of the physical features of the environment and the creatures that inhabit it can be learned from Moby Dick. Mark Twain is not only a marvelous source of wisdom about the nature of the environment of the United States from the Mississippi westward, but also a rather incisive critic of the irrelevance of science which loses connection to the realities of life. As the critic Leo Marx reminds us, "Anyone familiar with the work of the classic American writer (I am thinking of men like Cooper, Emerson, Thoreau, Melville, Whitman, and Mark Twain) is likely to have developed an interest in what we recently have learned to call ecology." 


Unfortunately, this literary heritage has not been enough to save us from ecological disaster. After all, every American technician, industrialist, agriculturist, or public official who has condoned or participated in the assault on the environment has read at least some of Cooper, Emerson, Thoreau, Melville, Whitman, and Mark Twain. Many of them are campers, birdwatchers, or avid fishermen, and therefore to some degree personally aware of the natural processes that the science of ecology hopes to elucidate. Nevertheless, most of them were taken unawares by the environmental crisis , failing to understand, apparently, that Thoreau's woods, Mark Twain's rivers, and Melville's oceans are today under attack. 


The rising miasma of pollution has helped us to achieve this understanding. For, in Leo Marx's words, "The current environmental crisis has in a sense put a literal, factual, often quantifiable base under this poetic idea [i.e., the need for human harmony with nature]." This is perhaps the major value of the effort to show that the simple generalizations which have already emerged from perceptive human contact with the natural world have a valid base in the facts and principles of a science, ecology. Thus linked to science, these ideas become tools for restoring the damage inflicted on nature by the environmental crisis.