Perspectives on Biology

1 PERSPECTIVES ON BIOLOGY Before immersing ourselves in the subject of environmental biology, in this chapter we consider factors to motivate, facilitate, and provide a context for that study. Thus, we start by discussing reasons, history, mindsets, and ethics that can guide our approach to the subject. 1.1 WHY ENVIRONMENTAL ENGINEERS AND SCIENTISTS SHOULD STUDY BIOLOGY For an environmental scientist, the answer to the question posed in the title of this section is fairly evident. However, for environmental engineers it is worthwhile to consider this in more detail. For example, environmental engineers need to know a broader range of science than does any other kind of engineer. Physics has always been at the core of engineering, and remains so for environmental engineers concerned with advective transport (flow) in the fluid phases of our world. The involvement of environmental engineers with chemistry has increased. Formerly, it was limited to chemical precipitation and acid–base chemistry in water, and relatively simple kinetics. Now it is necessary also to consider the thermodynamics and kinetics of interphase multimedia transport of organics, the complex chain reaction kinetics of atmospheric pollutants or of ozone in water, and the organic reaction sequences of pollutant degradation in groundwater. In a similar way, the role of biology in environmental engineering has burgeoned. Traditionally, the biology taught to environmental engineers has emphasized microbiology, because of its links to human health through communicable diseases and due to our ability to exploit microorganisms for treatment of pollutants. Often, there is a simple exposure to ecology. However, the ecology that is taught is sometimes limited 1 2 PERSPECTIVES ON BIOLOGY to nutrient cycles, which themselves are dominated by microorganisms. As occurred with chemistry, other subspecialties within biology have now become important to environmental engineering. Broadly speaking, there are three main areas: microbiology, ecology, and toxicology. The roles of microbiology are related to health, to biological pollution control, and to the fate of pollutants in the environment. Ecological effects of human activity center on the extinction of species either locally or globally, or to disturbances in the distribution and role of organisms in an ecosystem. Toxicology concerns the direct effect of chemical and physical pollutants on organisms, especially on humans themselves. This book aims to help students develop their appreciation for, and awareness of, the science of biology as a whole. Admittedly, applied microbiology is often included in many environmental engineering texts, focusing on disease transmission, biodegradation, and related metabolic aspects. However, little if any material is provided on the broader realm of biology in relation to environmental control. Such an approach notably overlooks a considerable number of important matters, including genetics, biochemistry, ecology, epidemiology, toxicology, and risk assessment. This book places this broad range of topics between two covers, which has not been done previously. There are other factors that should motivate a study of biology in addition to the practical needs of environmental engineers and scientists. The first is the need to understand the living world around us and, most important, our own bodies, so that we can make choices that are healthy for ourselves and for the environment. Another is that we have much to learn from nature. Engineers sometimes find that their best techniques have been anticipated by nature. Examples include the streamlined design of fish and the countercurrent mass-transfer operation of the kidney. An examination of strategies employed by nature has led to the discovery of new techniques that can be exploited in systems having nothing to do with biology. For instance, the mathematical pattern-recognition method called the artificial neural network was inspired by an understanding of brain function. New process control methods are being developed by reverse-engineering biological systems. Furthermore, there may be much that engineers can bring to the study of biological systems. For example, the polymerase chain reaction technique that has so revolutionized genetic engineering was developed by a biologist who was starting to learn about computer programming. He borrowed the concept of iteration to produce two DNA molecules repeatedly from one molecule. Twenty iterations quickly turn one molecule into a million. Engineers can also bring their strengths to the study of biology. Biology once emphasized a qualitative approach called descriptive biology. Today it is very much a quantitative science, using mathematical methods everywhere, from genetics to ecology. Finally, it is hoped that for engineers the study of biology will be a source of fascination, opening a new perspective on the world that will complement other knowledge gained in an engineering education. 1.2 PRESENT PERSPECTIVES ON ENVIRONMENTAL ENGINEERS AND SCIENTISTS Science is defined as ‘‘knowledge coordinated, arranged, and systematized’’ (Thatcher, 1980). The McGraw-Hill Dictionary of Science and Engineering (Parker, 1984) defines engineering as ‘‘the science by which the properties of matter and the sources of power in nature are made useful to humans in structures, machines, and products.’’ PRESENT PERSPECTIVES ON ENVIRONMENTAL ENGINEERS AND SCIENTISTS 3 Thus, engineering is defined as one of the sciences. Yet in the professional world, those who classify themselves as scientists and those who call themselves engineers seem to distinguish themselves from each other. To be sure, engineers study the sciences relevant to their disciplines, although not as deeply as scientists might prefer (the subject of this book being an instance of this). On the other hand, wouldn’t scientists benefit from a better understanding of how to apply engineering analysis to their fields? For example, aren’t mass and energy balances or transport phenomena useful for analyzing the multiplicity of phenomena affecting a laboratory experiment? The following comparison of engineers’ and scientists’ approaches were obtained from the authors’ observations, plus informal discussions with science and engineering practitioners. They reflect the perception of differences between engineers and scientists, not necessarily reality. They certainly do not apply to all. A common complaint to be heard from a scientist about an engineer is that the latter ‘‘wants to reduce everything to a number’’ and tends not to look at the system holistically. This may be due to the basic function for which an engineer is trained—to design: that is, to create an arrangement of matter and energy to attain a goal or specification, using the minimum amount of resources. Ultimately, this is reduced to such things as how big, how much, or for how long an arrangement must be made. An engineer designing an in situ groundwater bioremediation project uses models and design equations (and judgment) to determine flow rates, well locations, nutrient dosages, duration of treatment, and finally, the financial resources needed to eliminate a subsurface contaminant. However, nonquantitative factors may be just as important to the success of a project. Are microorganisms present that are capable of utilizing the contaminant? In fact, is the contaminant biodegradable at all? Are the by-products of the biodegradation process more or less toxic than the starting material? Although such considerations are taught in engineering courses, a quick look at homework and exams shows that the emphasis is on the ‘‘single-valued outcome,’’ the bottom-line answer. Paradoxically, there is also a sense in which an engineer’s approach is more holistic than a scientist’s. To make a problem tractable, the scientist may simplify a system, such as by considering it as a batch or closed system: one in which material cannot cross the boundary. Alternatively, a scientist may restrict systems to be either constant temperature or adiabatic (insulated): a reaction in a beaker, microbial growth in a petri dish, or a laboratory ecosystem known as a microcosm. An engineer deals more often with flow or open systems. He or she will literally turn on the pump, adding and removing material and energy. The underlying process is the same from a scientist’s point of view. However, the study of open systems is dealt with much more often in engineering courses than in science courses. This study enables scientific principles to be applied more directly to real problems in industrial or environmental situations. An engineer may be more likely to draw conclusions inductively from previous cases to find solutions to a problem. On the other hand, a scientist prefers to avoid assumptions and to base decisions on case-specific information only. For example, in examining a contaminated landfill, an engineer expects it to be similar to others in his or her experience, until information to the contrary appears. A scientist may be more deductive and may be reluctant to proceed until a thorough study has been conducted. The former approach is more economical, except when unanticipated problems arise. The latter approach is more rigorous but may sometimes be impractical because of cost. One must decide between the risk of overlooking unexpected problems vs. that of experiencing ‘‘paralysis by analysis.’’ 4 PERSPECTIVES ON BIOLOGY A scientist is looking for knowledge; an engineer is looking for solutions. Thus, when an engineer is done with his or her work, a problem has been solved. When a scientist is done, there may be more questions than before. Engineers are trained to consider the cost-effectiveness of their actions. Economic feasibility may be farther down the list of a scientist’s priorities. Some engineers are more willing to make environmental trade-offs; an environmental scientist prefers to ‘‘draw the line’’ against any environmental costs. If wetlands would be destroyed by a project, an engineer may weigh it against the value of the project. If the project is important enough, the value of the wetlands may be compensated for by mitigation or by replacement methods. A scientist may accept the necessity of this, but may still consider the loss of the original wetlands a tragedy. The tasks of both scientists and engineers are to explain (analyze), predict (forecast), and prescribe (design). A scientist needs to know about all of the individual phenomena that may affect a system and how they are related. An engineer often depends on having a mathematical model to represent the phenomena. If such a model can be created, engineers can produce quantitative results. However, science comes into play again when the limitations of the model are considered. These include extreme conditions where assumptions of the model may be violated and effects of phenomena (and every system will have such phenomena) that are not amenable to mathematical modeling. For example, suppose that an industry that uses well water from a shallow aquifer is having problems with iron in the water. After use, the water is contaminated with biodegradable organics and ammonia and is treated in a lagoon system before discharge to surface water. In considering the pollutional inputs to the system and an analysis of the groundwater, a scientist, might identify the problem as being due to a recycling effect where some of the water seeps from the lagoon into the soil, whereupon microbially mediated nitrification consumes some of the alkalinity in the water, lowering the pH, dissolves iron from the soil, and then is again taken up in the well. The scientist might then prescribe a long-term solution involving adding alkalinity to the water after use. An engineering approach might be to model the system using acid–base chemistry to predict the effect of the nitrification on the effluent, followed by groundwater flow and water quality modeling to predict the water quality at the well. The model could be used to determine the alkalinity dosage required, leading to a design for the treatment process. This process started with a scientific analysis and continued with engineering methods. Now, suppose further that after implementation, the lagoon effluent being discharged to the surface water is found toxic to fish. Again, a scientific analysis is called for: a toxicity identification evaluation (TIE). It may be found that at the higher pH, more of the ammonia in the effluent is in non-ionized form, which is more toxic to fish than is the ammonium ion. No one will doubt that science and engineering cannot be divorced from each other, but the better that engineers and scientists understand each other’s disciplines, the better the outcome will be. The engineering approach can be fruitful for scientific inquiry. Consider the problem of explaining why multicellular life-forms evolved. A biologist may think first of survival, fitness, and adaptation. An engineering approach might focus on considerations of energy efficiency and the effect of area/volume ratio on mass and energy transfer between the organism and the environment. Both approaches are valid and contribute to understanding. Engineers and scientists have much to learn from one another, which they do by working together. In addition, both will profit from a direct study of each other’s disciplines. PAST PERSPECTIVES ON ENVIRONMENTAL ENGINEERS AND SCIENTISTS 5 There are many instances in this book of mathematical or engineering analysis applied to biology. These should help convince engineers that biology really is a ‘‘hard’’ science. By learning and applying knowledge of biology, engineers can help convince scientists that engineering isn’t always simplification and abstraction—that they can take into account the full complexity of a system. At the same time, engineers should be humble about their capability. The following statement by LaGrega et al. (2001) with respect to toxicology should be true of other biological disciplines as well: ‘‘What is the single, most important thing for an engineer to know about toxicology? The engineer cannot and should not practice toxicology.’’ Still, the more the nonspecialist understands, the better his or her decision making will be. 1.3 PAST PERSPECTIVES ON ENVIRONMENTAL ENGINEERS AND SCIENTISTS Environmental biology is not a unified discipline. Almost every chapter in this book could constitute a different field with its own history. What we can describe here is a bit of history of the development of the associations that have formed between biology and environmental engineers. Barely a century ago, environmental and sanitary issues were largely the domain of scientists rather than engineers. In fact, long before the practice of environmental engineering had ever been conceived, physicists, chemists, and biologists were already hard at work investigating a range of pollution problems that they recognized as a serious threat. These sorts of concerns about procuring clean waters and discarding wastes safely had actually been documented and addressed for at least two millennia. However, by the time that Charles Dickens had written his classic, A Tale of Two Cities, the ‘‘worst of times’’ had truly befallen most industrialized countries. Humankind’s waste emissions had finally overtaxed nature’s assimilatory capacity, and the telltale signs were readily evident. Skies were blanketed with coal smoke and soot, rivers were befouled with a sickening blend of filth, and waste piles offered frightful opportunities for the dissemination of disease. In the latter half of the nineteenth century, the heightened level of pollution brought by the Industrial Revolution triggered a response from scientists, whose contributions continue to this day. For example, one of England’s leading chemists, Edward Frankland, routinely monitored water quality changes in the Thames River, and his microbiologist son, Percy, tried to resolve the bacterial reactions found in sewage. John Tyndall, a renowned physicist, focused a considerable amount of his talent on air quality and contaminant analysis problems. Charles Darwin’s eminent friend and staunch supporter, Thomas Huxley, played a major role in the cause of sanitary reformation as a practical extension to his expertise in biology. The roots of our modern practice of environmental engineering sprang largely from the sciences. These investigators were not motivated by regulatory requirement, legal threat, or financial gain. Instead, their fledgling efforts were effectively compelled by personal concerns about an environment whose quality had already deteriorated seriously. These scientists had been trained to appreciate the balance of nature and were duly concerned about the stress imposed by a rapidly escalating range of pollution problems. It was the field of biology, however, which truly gave these yesteryear environmental efforts their 6 PERSPECTIVES ON BIOLOGY highest motivation. Biologists working at the end of the nineteenth century demonstrated successive refinements in their sense of awareness and appreciation for the technical importance of the environmental problems that they faced. The connection between biology and environmental engineering is best demonstrated by tracing the academic lineage extending beyond Thomas Huxley’s seminal work with sanitary health. Although apparently self-educated, Huxley was a preeminent leader in the emerging field of biology late in the nineteenth century and gained worldwide recognition for his forceful backing of Charles Darwin’s evolutionary theories. Having been invited to present the opening speech for Johns Hopkins University’s inaugural ceremony in 1894, he used the opportunity to recommend one of his students H. Newell Martin, as chairman of the first biology department in the United States. Under Martin’s leadership, students were imbued with an inherent sense of ‘‘environmental’’ concern. For William Sedgwick, this issue became a lifelong cause. After receiving his doctorate, Sedgwick joined the biology program at Harvard, where he introduced a radical new focus on sanitary matters. Together with his own student, George Whipple, he then cofounded public health programs at Harvard and the Massachusetts Institute of Technology (MIT), which in the coming years would lead formatively to distinct academic offerings in public health, sanitation, and industrial hygiene. At much the same time, Sedgwick and Whipple created a technical program at MIT that dealt with the applied aspects of sanitary science, thereafter known as the first-ever environmental engineering program. 1.4 AMBIGUITY AND COMPLEXITY IN BIOLOGY Often in fields such as physics or engineering it is possible to identify all the variables that affect a process (in terms of a model). In fact, the number of variables can be reduced to a minimum by the use of dimensional analysis, producing a set of dimensionless numbers that describe a situation completely. In biology, it is more common for there to be unknown influences and obvious gaps in our knowledge. Consequently, many biological ‘‘facts’’ are conditional—answers often have to be prefaced with ‘‘it depends . . .’’ or important questions may be totally lacking an answer. Despite the recent explosion of knowledge in chemical genetics, we still cannot give a satisfactory explanation of how an embryonic cell ‘‘knows’’ to grow into part of a fingertip and not a hair follicle. We need to have a certain humility in our studies: In school we start each course at the beginning of a long book full of things that are known but that we do not yet know. We understand that beyond that book lies another book and that beyond that course lies another course. The frontier of knowledge, where it finally borders on the unknown, seems far away and irrelevant, separated from us by an apparently endless expanse of the known. We do not see that we may be proceeding down a narrow path of knowledge and that if we look slightly left or right we will be staring directly at the unknown. (Gomory, 1995) Few appreciate the difficulty of making ironclad distinctions in the study of biology. Actually, the same is true for all fields, although it is perhaps more apparent in biology. In engineering, the mathematical constructions create an abstract ideal out of concepts. When we speak of the velocity of water in a pipe, the idea seems very clear and can be manipulated fairly unambiguously, such as to compute flow or pressure drop. However, AMBIGUITY AND COMPLEXITY IN BIOLOGY 7 if the turbulent nature of the flow is examined in detail, we find that we need to use probability distributions to describe the velocity, and even that is incomplete. We use the simplified abstraction so often, and with such success, that we often forget the underlying complexity. In biology, the uncertainties behind the abstractions are often closer to the surface. For example, consider the concept of species. We would like to define species such that all living things belong unambiguously to a species. This turns out to be impossible. One definition is that a species is a group of organisms that interbreed with each other in nature and produce healthy and fertile offspring. Thus, the horse and the donkey are different species even though they can mate, because all their offspring are infertile. A number of problems occur with this definition. First, not all organisms reproduce by breeding (sexual reproduction). More important for this discussion is that there are populations we would like to define into separate species that can interbreed, such as the domestic dog and the African golden jackal. So perhaps we would alter the definition to include organisms that can potentially interbreed. However, there are cases in nature where organism A can breed with B, B with C, C with D, but D cannot breed with A. Similar problems occur every time we make a classification. The euglena is a singlecelled organism that can move at will through its aqueous environment. This motility, together with its lack of a cell wall, would indicate that it should be classified as an animal. However, it has the green pigment chlorophyll, which enables it, like a plant, to capture light energy. Biologists have created a separate category, the protists, in part to eliminate the problem of where to put the euglena. However, some protists, the algae, are very similar to plants; others, such as protozoans, are animal-like. Thus, the classifications lack an iron-clad quality. Textbook definitions sometimes include the word mostly, as in ‘‘animals are mostly multicellular.’’ Whether an organism is single-celled or multicellular is an important characteristic used in classification. However, some may either be at different stages in their life cycle or may simply change in response to environmental conditions. The slime mold is an unusual organism that grows on the forest floor and behaves at one stage as a mass of single-celled protozoans; at another stage the cells fuse into a single supercell with many nuclei; and at yet another stage it forms fruiting bodies on stalks resembling a plant. Another idea that must be recognized as somewhat arbitrary is the notion of an event. This is another kind of useful fiction. In classical science (i.e., other than in quantum mechanics), there are no events, only processes. Consider the ‘‘moment of conception,’’ when a sperm enters and fertilizes an egg. Examined more closely, we must realize that the event consists of a sequence of changes. If we say that fertilization occurs as soon as a sperm penetrates an egg’s cell membrane, we must ask, ‘‘penetrates how far?’’ If, instead, we place the event at the moment that the chromosomes join into a single nucleus, we must ask how complete the joining must be. It is like asking when two asymptotic curves combine. The problem is not that science cannot say when the critical moment occurs. No such moment actually exists. Another thing that is important to appreciate about biology is that a certain amount of caution is necessary when making predictions or judgments about the validity of reported observations. Living things often surprise and contradict. The following quote by the Dutch biologist C. J. Brejèr (1958) applies as well to biology as a whole: ‘‘The insect world is nature’s most astonishing phenomenon. Nothing is impossible to it; the most improbable things commonly occur there. One who penetrates deeply into its mysteries 8 PERSPECTIVES ON BIOLOGY is continually breathless with wonder. He knows that anything can happen, and that the completely impossible often does.’’ There is no perfect way around these difficulties; the complexity of nature sometimes resists our attempts to coordinate, arrange, and systematize it. All life-forms are unique, defying easy classification; so we create a working definition and go on. We must use the distinctions when they are useful and alter them when they’re not. Biology is also unique in the number of levels of scale that it is necessary to examine in its understanding. In Section 2.2 we describe how living systems can be examined at many levels of detail, from the chemical to the cell to the organism to the ecosystem. Within each level are numerous types of entities (e.g., cells or organisms) and myriad instances of each type. The number of potential interactions is staggering. Sometimes the reductionist approach is appropriate and an individual entity or interaction will be studied almost in isolation. Other times it is necessary to look holistically at the behavior of the group. It is often the goal of scientific studies to ‘‘explain’’ behaviors observed at one level by looking at behaviors of its component parts. For example, the primary productivity (production of algal biomass) of a eutrophic lake can be predicted by measuring the productivity of individual species cultured in a lab under similar conditions. However, it is often the case that the aggregate behavior of numerous individuals cannot be predicted straightforwardly, even if the behavior of the individuals were well understood. For example, proteins are polymers of 20 different amino acids, in varying sequences. Although the individual amino acids do not function as catalysts, proteins do. A protein is not simply the ‘‘sum of its parts.’’ ‘‘New’’ properties that arise from the interaction of numerous similar parts are called emergent properties. A mathematical field of study called complexity theory has arisen to study the relation between large numbers of interacting autonomous parts and resulting emergent properties. A related source of complexity is chaotic behavior. Chaos is dynamic behavior characterized by ‘‘extreme sensitivity to initial conditions.’’ Consider the sequence of real numbers, (x1, x2, . . .) between 0.0 and 1.0 generated by what is known as the quadratic iterator: ð1:1Þ xiþ1 ¼ 4xi ðxi
1Þ Figure 1.1 shows plots of two such series that start at nearly the same point, 0.9000 and 0.9001, plus a plot of the difference between the two series. Note that after a dozen iterations the two series become uncorrelated. The difference between the two series seems almost random. This demonstrates that although we know the rule generating the data, without perfect knowledge of the initial condition, we cannot predict very far into the future. This extreme sensitivity to initial conditions is also called the butterfly effect, after the analogy for chaos in weather systems which states that a butterfly flapping its wings in Beijing can cause a hurricane in New York City two weeks later. A consequence of chaotic behavior is that extremely complex behaviors can result from very simple rules, as in the example just given. The paleontologist Steven Jay Gould proposed that small mutations can greatly alter body plans, producing great leaps in evolution. The benefit of this for the study of biology is that complex processes do not rule out the possibility of simple explanations. The difficulty is that it places a limit on the reductionist view. Having a high degree of understanding of the dynamics of nerve cells does little to explain how the human brain can so quickly recognize a face or decide on a chess move. CONSERVATION AND ENVIRONMENTAL ETHICS 9 a. Initial point = 0.9000 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0 5 10 15 20 25 30 25 30 b. Initial point = 0.9001 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0 5 10 15 20 c. Difference between the two series. 1.2 0.8 0.4 0.0 –0.4 –0.8 –1.2 0 5 10 15 20 25 30 Figure 1.1 Quadratic iterator, illustrating chaotic behavior and extreme sensitivity to initial conditions. 1.5 CONSERVATION AND ENVIRONMENTAL ETHICS The study of biology helps create an increased appreciation for the natural world. It causes us to question our collective and individual actions that may harm it. However, we seem to be constrained in our concern by our own need for survival. What is needed is an ethic to answer questions such as: How should we value the natural world? What is our place in it? What are our responsibilities toward it? Why do we pollute, in effect spoiling our own nests? The problem is in a paradox of individual freedom that is called the tragedy of the commons (Hardin, 1968): 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. 10 PERSPECTIVES ON BIOLOGY 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 þ1. 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 decisionmaking 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. Morality is about when we should act against our own immediate self-interest. Ethics is the study of systems for deciding the morality, or rightness or wrongness, of our actions. Environmental ethics is the study of the morality of actions that affect the environment. An understanding of environmental ethics will help us to apply the knowledge and power we gain from our education. It is a popular saying that one cannot teach someone to be ethical. This is not true. Public educational campaigns are often used with good effect to encourage ‘‘right’’ behavior, such as to institute recycling programs. Furthermore, an understanding of ethical principles can help counter specious or just plain wrong arguments that people sometimes use in support of self-serving actions. Finally, an understanding of ethics can help guide and reinforce those who want to do the right thing. A moral principle is a rule or set of rules used to decide moral questions. Several moral principles have been proposed that are specific to our effect on the environment. A moral principle will not be an infallible guide to behavior. We will still be faced with dilemmas in which each alternative has its own moral cost. What is the basis of moral principles? James Q. Wilson argues that we have inborn ‘‘moral senses,’’ including the senses of sympathy, fairness, self-control, and duty. These senses then propel the development of moral principles. The Harvard biologist Edward O. Wilson postulates that concern for the environment stems from an innate affinity that people have for all living things, a principle he calls the biophilia hypothesis. This affinity becomes most apparent when contact with living things is limited. Antarctic researchers who are isolated over the winter must ration time spent in the plant growth chamber. The station’s doctor prescribes such time to treat depression. NASA has conducted experiments in which crews are isolated in closed environmental systems for as long as 90 days to simulate space missions. The crew in one such experiment found that one of their greatest pleasures was growing their small lettuce crop. Planting and harvesting decisions were made only after considerable group discussion, and crew members often enjoyed opening the growth chamber just to look at the plants. Two basic types of ethics are utilitarian ethics and rights-based ethics. Utilitarianism is the principle that rules or acts are moral if they produce the greatest amount of good for all concerned. A problem for utilitarianism is that some may suffer unfairly for the greater CONSERVATION AND ENVIRONMENTAL ETHICS 11 good of the majority. Rights-based ethics get around this problem by postulating moral rights that are universal (possessed by all), equal (no one has the right in any greater or lesser degree than another), inalienable (cannot be given up or taken away), and natural (not created by human acts, as are legal rights). A major problem with rights-based ethics is that different rights may conflict, and criteria need to be selected for choosing among them. Both of the aforementioned types of ethics are focused on needs of individuals and thus are humanistic. Some propose a holistic ethic that places value on systems rather than individuals. This approach is used to raise to the level of moral principles ideas such as the diversity and integrity of ecosystems or the sustainability of economic systems. The Judeo-Christian tradition forms the basis of much of Western thought. Various interpretations have been applied to its view of the relationship between humans and the rest of the natural world. A negative view has been blamed on the biblical injunction to ‘‘have dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth. . . . Be fruitful, and multiply, and replenish the earth, and subdue it: and have dominion over the fish of the sea, and over the fowl of the air, and over every living thing that moveth upon the earth’’ Genesis 1:26–28. However, other passages imply that all of creation has value. Genesis 1:31 states that ‘‘God saw every thing that he had made, and, behold, it was very good.’’ The animals are also commanded to be fruitful and multiply. This leads to the stewardship concept, which states that humans have responsibility for the protection of creation. In any case, the Western tradition developed in which humans were viewed as the center and pinnacle of creation, a notion that is called anthropocentrism. Some Asian religions, such as Zen Buddhism, Taoism, and Hinduism (especially the Buddhists), teach unity with nature, including compassion toward other humans as well as animals. For native Americans, unity means an interdependence and kinship between all animals, including humans, and natural systems. They believe that all animals have spirits that deserve respect. Animals can only be killed out of necessity, after which humans have to make apologies and atonement to the spirit of the killed animal. Many tribes also link their identity to prominent landscape features. The Darwinian revolution dethroned humans from their special position in creation. Instead, they are part of a continuum with the animals, plants, and ultimately with the nonliving chemical world. The other parts of the living and nonliving world are seen as kin, which gives us an incentive to make our ethic include that which is good for them. The wildlife biologist and amateur philosopher Aldo Leopold (1949) proposed such an ethical system in his book A Sand County Almanac. He calls it the land ethic. This book is considered the ‘‘gospel’’ of the conservation movement, much as Rachel Carson’s (1962) Silent Spring sounded the alarm that stimulated the environmental movement. The idea of a land ethic is developed further by Callicott (1986). Leopold describes how ethics developed from responsibilities toward other people. Eventually, these responsibilities were expanded to include the family and the clan, and then larger and larger groups, ultimately encompassing all of society. As the boundaries of the community expanded, the inner ones remained. These can be viewed as a concentric hierarchy of responsibilities to larger and larger communities (Figure 1.2): from self to nuclear family, extended family, clan, nation, and all of humanity. A person’s responsibility toward the outer rings does not cancel the inner ones, but rather is layered 12 PERSPECTIVES ON BIOLOGY The Individual Individual The Family Family The The Nation Nation The Humanity Humanity TheLand Land The Figure 1.2 Hierarchy of responsibility in the land ethic. over them. Leopold’s contribution was to describe this hierarchy and to extend the idea of community to include the land. By the land he meant not just the soil but the pyramid of energy starting with the soil, to the plants it supports, the herbivores that live on the plants, the predators that depend on all the levels below it, and the organisms of decay that return the nutrients to the soil. Furthermore, the particular responsibilities due each layer in the hierarchy are different. One does not owe all of humanity the same share of attention and resources that is owed to family members. So what is our responsibility to the land? According to Leopold, human use of the land should preserve and enhance the diversity, integrity, stability, and beauty of the biotic community. This does not prohibit our use of natural resources but requires that we do so in a sustainable way with a minimum of waste. This leads us to one of the great moral challenges before our society. At the same time that the world’s population continues to increase, the per capita use of natural resources is also increasing, and wilderness habitats are continually giving way to human uses. Optimists may expect that continuing technological developments will enable growth to continue. However, eventually we will have to achieve a steady-state condition in which resources are consumed at essentially the same rate at which they are regenerated. Humans have the capacity to plan, so society has the potential to bring about such a steady state without having it imposed by catastrophe. How will such a ‘‘sustainable society’’ look? What will be its population, how much will each person have to eat, and how much will remain of the wilderness and biodiversity that we have today? Although a sustainable society may take generations to become reality, it will never happen unless earlier generations begin to bring it about. GUIDELINES FOR STUDY 13 A final note of particular relevance to an engineer or scientist is professional ethics, often stated in a code of ethics. An example is the code of ethics adopted by the American Society of Civil Engineers, which states their responsibilities to the environment:  Engineers uphold and advance the integrity, honor, and dignity of the engineering profession by using their knowledge and skill for the enhancement of human welfare.  Engineers shall hold paramount the safety, health, and welfare of the public in the performance of their professional duties.  Engineers should be committed to improving the environment to enhance the quality of life. 1.6 GUIDELINES FOR STUDY In many of the fields of science the task of ‘‘coordinating, arranging, and systematizing’’ the knowledge can be difficult precisely because mathematics cannot easily be applied. Although mathematics has the reputation of being a difficult subject, it is tremendously efficient at compressing information. If a picture is worth a thousand words, an equation is worth a thousand pictures. Consider, for example, the effect of temperature, volume, and composition on the total pressure of a mixture of three solvents in equilibrium with its vapor, or the shape of the cone of depression around a well as it depends on soil permeability and water flow. We cannot easily visualize high-dimensional relationships, so they must be represented by a family of curves. Alternatively, the information could be contained concisely in a single mathematical representation. However, biological systems often are not described so compactly. This leads us to discuss how to approach the study of biology. The method usually first thought of is to apply memorization. This is laborious and unproductive. It is extremely difficult to keep numerous unconnected facts in your head for any amount of time. The key, then, is to establish connections, to seek out relationships. This recovers some of the efficiency of the mathematical equation. We can think graphically about concepts, mentally plotting developmental trends, sequences, patterns, and networks of relationships. Make studying an active process by keeping notes: Outline the reading and write lists, even lists of lists, under a unified topic. See if you can create an explanation of the concepts in each section of this book in your own words. If you have trouble with this at some point, you should formulate the difficulty as a question and seek the answer in the references or from your instructor. To learn a complex relationship from a figure such as the oxidation of glucose in Figure 5.5 or the nitrogen cycle in Figure 14.7, try copying it (possibly with less detail), and then try reproducing it again with the book closed. Create what are known as concept maps. These are graphical representations of the relationships among information. For example, Figure 1.3 shows a concept map for science and engineering science topics in environmental engineering education, emphasizing the place of biology and leading to the twin roles of environmental engineers: design and prediction. To create a concept map, start with a list of related concepts. Then, state an organizing principle, which is a concept or idea used to arrange and connect items appropriately. The organizing principle behind Figure 1.3 is that connections lead from one topic to others that require their application. Another arrangement of 14 PERSPECTIVES ON BIOLOGY Mathematics General Chemistry General Physics Organic Chemistry Biochemistry Fluid Mechanics Physical Chemistry General Biology Mass Transfer Environmental Microbiology Mass Balance and Reactors Environmental Chemistry Ecology Toxicology Treatment Process Design Environmental Modeling and Impact Prediction Figure 1.3 Concept map. the items could have been created using a different organizing principle, for example as the sequence in which the subjects developed historically. Such data structures organize and compress information, creating a mentally retrievable path to the information when called for. There is no right or wrong way to create structures. As long as it makes sense to you, it’s right. The act of creating them results in learning. In addition, this technique is an excellent way to communicate any kind of technical data to others. Besides the organizing techniques just described, the major activity for the study of biology is simply to read. Read beyond the required material. Seek out the references—these expand and reinforce the basic concepts. Multiple sources of information on the same topics can provide alternative viewpoints that highlight and clarify the key information. PROBLEMS 1.1. Create a concept map using the chapters of this book as a starting list of items to be related. What organizing principle are you using? 1.2. How would responsibility to your employer or to your consulting client fit into Aldo Leopold’s hierarchy? Where do government regulations come in?