Human existence depends inextricably on other life forms. All humans need Earth's flora, fauna, and microorganisms for sustenance, materials, energy, and even the air they breathe. We all have the capacity to learn from and enjoy life on Earth through its diverse beauty, complexity, and invention. Some humansparticularly scientistsdedicate themselves to exploring the secrets of the incredible array of biota on our small, blue planet. Through the deeper understanding that their work provides, all humans can directly or indirectly derive benefits. But how much of Earth's biotic complexity do we, as citizens or scientists, understand, and what more do we most need to find out to ensure that Earth's biota can continue to provide for us and for generations to come?
The extent and variability of life on Earth is referred to as “biodiversity.” Scientists in many disciplines have engaged in extensive exploration of biodiversity. Many exciting advances in understanding have occurred in the last decade, since the National Forum on BioDiversity was held in Washington, DC, in 1986, under the auspices of the National Academy of Sciences and the Smithsonian Institution. The advances have taken place because scientists have identified new theoretical frameworks, developed new technologies to observe life in the field, and analyzed new data while discovering tens of thousands of new kinds of organisms. Thus, our collective knowledge is growing rapidly. But many scientific advances are still needed, and much current information is not widely known beyond the community of scientists who study biodiversity.
The National Academy of Sciences, the Smithsonian Institution, the Library of Congress, and the American Association for the Advancement of Science rec-
ognize that advancing the biodiversity sciences and improving public understanding of it require effective communication between the public and the scientific community. To that end, those four organizations convened the Second National Forum on BiodiversityNature and Human Society: The Quest for a Sustainable Futureon October 27–30, 1997. The 3-day conference was held at the National Academy of Sciences in Washington, DC. The papers presented in this volume are based upon presentations made at the conference. The material in this book is not an official report of the Board on Biology or the National Research Council and any opinions expressed are solely those of the individual forum participants.
The second forum provided a venue for the world's leading experts in the biodiversity sciencesranging from agronomy to zoologyto discuss their understanding and future scientific directions. Through the World Wide Web, it engaged the experts in a dialogue with the American public about biodiversity, especially its relevance to humans, our understanding of it, and the challenges that lie ahead. The forum had three goals, as follows:
• Review state-of-the-art science that helps us to understand Earth's biological diversity. The forum accomplished that goal by engaging scientists who work in fields that focus on different aspects of the extent and variability of life on Earth. The activities of the forum provided opportunities for scientists to share new information with each other and the public, to confirm some theories and refute others, to discuss emerging fields that need new information, and to develop strategies to learn more about biodiversity and the proper management of it.
• Engage scientists and nonscientists in a discussion of what science is, how it works, and the issues that scientists should address, including issues of practical importance to the public. That goal was accomplished by holding brownbag lunch sessions on each day of the forum where the speakers were available to discuss general questions posed to them by forum attendees.
• Make the information discussed at the forum accessible to the general public in an understandable way. This proceeding's volume accomplishes that goal. It is derived from the research literature and forum activities, and it explains biodiversity to the general public in lay terms.
Given those goals, what was perhaps most striking about the ideas presented at the forum was the discovery of the convergence that had occurred over the preceding decade between the concept of biodiversity, which used to be taken loosely to mean a roster of species, and the concept of “sustainable development.” It is now widely understood that biodiversity is what makes our planetary home what it is and makes our life here possible; in turn, it is biodiversity that we must use to build our sustainable future. The living systems of Earth are powered by perhaps 350,000 of the estimated 7 million or more species that share the planet with us: the plants, algae, and photosynthetic bacteria that alone have the ability to capture a small portion of the Sun's energy and transform it into chemical bonds, which in turn provide the energy needed for the metabolism of those organisms and indirectly for all others, including humans.
Our planet is 4.5 billion years old, and life existed at least 3.8 billion years ago. The earliest life forms were bacteria, and for at least 3.5 billion years of Earth history, cyanobacteriaphotosynthetic bacteriahave been changing the nature of the atmosphere from a reducing one to the oxidizing one we have today. The accumulated bodies of cyanobacteria have likewise over the years been transformed into the oil and natural-gas deposits that humans have been using, with coal, to power their industrial processes for more than 200 years. By about 1.5 billion years ago, the first eukaryotic cells (cells with nuclei) had appeared, in part as a result of processes of serial symbioses that provided the basis for their intracellular complexity. Eukaryotic cells had aggregated to form multicellular organisms by about 700 million years ago, and these multicellular organismsthe ancestors of terrestrial vertebrates, arthropods, fungi, and plantsinvaded the land, first becoming terrestrial about 430 million years ago.
On land, with its greater array of distinct habitats, organisms proliferated greatly. Today, some 85% of all living species occur on land, even given the much greater fundamental diversity of marine organisms. As terrestrial organisms evolved in part into larger and more complex forms, forests came into existence, by at least 300 million years ago; the masses of decaying vegetation from the forests, under suitable circumstances, became coal. In the forests and other vegetation types that characterized the world of the Mesozoic Era (65–245 million years ago), biological diversity increased greatly. The Mesozoic Era began with the most extensive extinction event recorded, the great majority of all living species disappearing forever, and ended with the most recent extinction event, that at the end of the Cretaceous Period, the third and final geological period into which the Mesozoic is divided.
About 65 million years ago, it is estimated that two-thirds of all terrestrial organisms disappeared; the character of life changed permanently. Perhaps 500,000 kinds of organisms survived the extinction event at the end of the Cretaceous, and they have gradually given rise to what has conservatively been estimated as 7 million kinds of living eukaryotic organisms today and an unknown number of kinds of prokaryotic ones (cells without nuclei). This great elaboration of life has resulted not only in the elaboration of species and the forms of individual organisms, but also in the development of increasingly complex biological communities, particularly at low latitudes.
We are now participating in the sixth great extinction event; again, an estimated two-thirds of the kinds of terrestrial organisms are threatened with extinction in the near future. The extinction event that closed the Mesozoic Era seems almost certainly to have resulted from the collision of an asteroid Earth somewhere off the end of what is now the Yucatan Peninsula, but humans are the active force driving the wholesale, massacre of living things that is taking place today. How has that come to be?
Our genus, Homo, evolved from Australopithecus in Africa some 2 million years ago but existed at relatively low population densities until quite recently, geologically speaking. At the time when our ancestors were developing crop agriculture, starting about 10,000 years ago, the human population of Earth numbered several million fewer than visit the Smithsonian museums each yearfar fewer than
the population of the Washington, DC, areascattered over Eurasia, Africa, Australia, North America, and South America at about the density of aboriginal people in Australia before European contact. With a dependable supply of food that could be stored, however, humans developed increasingly complex societies, went to war with one another, developed technologies to harness power of diverse kinds, formed states, and began to exert pressure on the living world to a degree that had not been experienced earlier.
With the accelerated growth in the human population, there were some 130 million people by the time of Christ, about 500 million in early Renaissance times, and about 1 billion at the start of the 19th century, when an English clergyman named Thomas Malthus was warning of the danger that population growth might outstrip our ability to feed ourselves. Our numbers had grown to 2.5 billion by 1950 and then the growth really underwent great acceleration: over just 50 years, 3.5 billion people have been added to the human population, and we shall enter the 21st century with more than 6 billion people spread throughout the world.
The illusion of abundant, cheap energy that we have created has fueled population growth by increasing the rate and intensity of all of our activities. Consider some of the changes that have occurred during the last 50 years. We have lost about one-fourth of the topsoil and one-fifth of our agricultural land, so that we are feeding 6 billion instead of 2.5 billion people with greatly decreased natural resources. We have altered the character of the atmosphere, adding about one-sixth to the atmospheric carbon dioxide, the primary greenhouse gas, and diminishing the stratospheric ozone layer by about 7%, thus increasing the incidence of skin cancer at middle latitudes in the Northern Hemisphere by about one-fifth. About one-third of the forests that existed in 1950 have been cut without being replaced, and human pressures continue to grow at such a pacefueled by growing numbers of people, increased affluence (consumption), and the use of inappropriate technologiesthat it is increasingly difficult for any ecosystem to regenerate itself.
Worst of all is the increased level of extinction, now hundreds of times above the background rate for the last 65 million years, as reviewed by Stuart Pimm and Thomas Brooks for this volume, and likely to lead to the disappearance of about two-thirds of all kinds of living organisms by the end of the next centuryan extinction event that would be, as mentioned above, roughly equivalent to the one that occurred at the end of the Cretaceous Period, but in this case driven by only one species: humans. Violating the principle enunciated by conservationist Aldo Leopold years ago“The first rule of intelligent tinkering is to save all the cogs and wheels”we are in the unfortunate situation of trying to build an “age of biology” while wasting the organisms that are of fundamental importance in meeting our objective, whether individually or collectively. There is ample reason to try to reverse the trend, but we seem to have neither the collective wisdom nor the will to attempt to do so in a meaningful way.
One of the most damaging illusions that is being perpetrated in our time is the one that because humans have solved other problems in the past history of Earth, they certainly can solve the ones that we are facing now. Such a view ignores the scale of the problem that we face, when we are consuming or wasting an
estimated 45% of all terrestrial net photosynthetic productivity, and using about 55% of the available fresh water. No pressures remotely like those have existed before. To build a world that is sustainableone in which animals, plants, fungi, microorganisms, and people will be able to continue to exist peacefully, harmoniously, and sustainably over the long run will require every ounce of wisdom, science, common sense, and affection for one another that we can possibly muster. Anyone who denies this conclusion is simply misinformed or uninterested in our common future; since you, dear reader, know better, you are obligated to tell them that they are wrong, to comport yourself, your business, your country, your neighborhood, your church, your National Academy of Sciences, or any other organization in which you are involved, in such a way as to help to make the future a pleasant, abundant, and prosperous reality instead of an increasingly devastated, homogeneous, and exhausted one.
This all became very personal for me when I saw Susan Middleton, that talented photographer, in the National Geographic movie that premiered at the forum, Don't Say Goodbye, stepping gingerly on rocks around my manzanita. I call it my manzanita, because I discovered that plant in 1952, the only known survivor of Arctostaphylos hookeri subsp. ravenii, when I was 15 years old and collecting plants in the Presidio of San Francisco, never imagining that it might be the only one or that so many species of organisms soon would be threatened with extinction. Instead of stepping gingerly around the plant as Susan did, I just walked right up to it, cut off a few branches for herbarium specimens, pressed them, and went on my way.
People weren't worried about extinction then, and few worried about human population growth. America was bustling with energy after the conclusion of World War II and after capturing nearly 40% of the world's economic activity, giving our nation an incredible level of prosperity that has never been duplicated in relative terms since and cannot realistically be duplicated in the future. In the United States we have about 4.5% of the world's population and control about one-fourth of the world's economy, but sometimes we seem incapable of recognizing our interdependence with the other nations of the world.
But to move forward with our storywe became increasingly concerned with population in the 1960s, when we had begun to recognize and to worry about our impact on the environment, both local and global. The first Earth Day was held in 1970; President Nixon signed the key environmental legislation, under which our country has operated since, in the early 1970s; and we moved forward, our national population and that of the entire world growing rapidly. As we have seen, we live in a nonsustainable world that we are destroying and homogenizing as we use up its resources; and the characteristics of our world are both unjust and unstable. Of the 6 billion people alive today, 2 billion live in abject poverty, with less than $1 per day in income; some 700 million are malnourished to the extent that their brains do not develop properly and their bodies are wasting away. The proportion of people living in industrialized countries has fallen from one in three in 1950 to one in five today; but the industrialized countries, with only one-fifth of the global population, control 85% of the world's economy, use comparable proportions of its resources, and cause a proportionate amount of pollution
and environmental degradation. Put another way, 80% of the people in the world live in developing countries, which have about 80% of the world's biodiversity (and by far the less well-known part of that biodiversity), 15% of the world's wealth, and no more than a tenth of the world's scientists, most of them in a few countries. Most of the world's biodiversity is in countries where there is little scientific basis for dealing with it or using it sustainably for the benefit of their people, so their biological heritage, which is of great common value to all people on Earth, is being lost without any chance of doing anything about it. By paying so little attention to so many poor people, we are discriminating against them, and particularly against the women and children who live among them, and thus denying ourselves the benefit of their creativity in addressing the serious problems that we are confronting together. We cannot afford to do that, whether we recognize the problem or not.
But what has happened since 1986, since we held the National Forum on Biodiversity? In general, I think we have come to recognize with Dan Janzen that the world is indeed a garden, and that humans are, for better or worse, responsible for all of it, dominating every ecosystem, depositing manufactured chemicals onto every square centimeter every minute. We dominate every ecosystem on Earth, as abundantly demonstrated by the papers included in this volume, and we ought to accept the responsibility of managing our planet much better and more sustainably than we are now: we owe such behavior to the future. A majority of all lands are intensively incorporated into human activities of one kind or another, and the proportion and intensity continue to grow rapidly. Parks and other protected areas must be viewed as special parts of human-dominated ecosystems and managed as such; there is no turning back to an earlier world, in which such areas might have been segregated and held apart from human activities.
In the year after First National Forum on BioDiversity, the report of the World Commission on the Environment and Development, the “Brundtland report”, was published as Our Common Future. That report, more than any other, popularized the concept of sustainable development and began to delineate the issues debated at Rio de Janeiro's Earth Summit in 1992, on which the future of all countries, all companies, all institutions, and all of nature ultimately depend. In putting together the concept of sustainable development with that of biodiversity, we have come to see that to preserve, nurture, rebuild, restore, and refresh the increasingly modified living systems that support us, we have one primary tool and that tool is biodiversity.
The concept that DNA is the carrier of genetic information was first reported in 1944, about 50 years ago. The first transfer of one gene from one kind of organism to an unrelated kind of organism took place in 1973, only about 25 years ago. And it is only in the last few years that we have begun to determine the complete sequences of genetic material of prokaryotic and eukaryotic organisms. Until now, no one could make a reasonable estimate of how much and how the genome of, say, corn differs from that of a human; we are just beginning to learn. If the 21st century ushers in the age of biology, we shall need to understand biodiversitythe incredible diversity of life on Earthif we are to be able to achieve the kinds of results that we confidently expect and that potentially have
such a great bearing on the human prospect. In that context, the impending extinction of perhaps one-fifth of the species of organisms within a quarter-century or two-thirds of the total within the next century is unacceptable, especially considering that we have even cataloged and named only about one-fourth of the total that we estimate exist.
Looking at the planet Earth from somewhere else, observers would find it impossible to believe that we have no common, well-organized international effort devoted to preserving our organisms. They would be incredulous at the thought that the rapidly shrinking 20% of us who live in industrialized countries have not long since joined hands with the people who live in developing countries, and by doing so created a collegial and mutually supporting economic situation within which it would be possible to save as complete as possible a selection of the world's biodiversity. The way we are behaving amounts to sheer madness, and we must find a way to stop it. Can we not find a way to do so?
As David Suzuki points out vividly, our response to the ecological crises we face is not appropriate, given the enormity of those crises; but we are facing thousands of ecological Pearl Harbors today, mostly without even noting them, much less making any effort to avert them. His powerful analogy presenting the state of the world's ecology as though we were all passengers in a huge car going as fast as possible toward a brick wall and just sort of chatting amiably as it speeds along, with most of the people in the world actually locked in the trunk: that's something to think about! At the very core of human existence, or of human prospects for the future, are the kinds of values that Jim Morton discusses in this forum. Why do we find them so hard to embrace and act on?
The situation that I have outlined briefly here, and that is discussed in a number of the papers in this volume, demands the reformulation of both philosophical systems and human actions around the principles of sustainability, with a proper appreciation of biodiversity at the heart of the matter.
Many responses are possible to the crises that are so well laid out in the papers included in this volume. It is clear that our knowledge of biodiversity is incompleteit is in no way adequate for the challenges that we face in trying to build a sustainable world. Even according to the conservative estimates presented by Bob May, we have named no more than one-fourth of the world's eukaryotic species, and the prokaryotic species are so poorly known that we cannot reasonably provide even an order-of-magnitude estimate of their numbers. We must therefore accelerate and at the same time make more selective our approaches to learning about global biodiversity: there is no hope of completing an inventory during a century in which up to two-thirds of the species are likely to vanish permanently. Completing the inventories of some better-known groups and those of economic importancesuch as vertebrate animals, butterflies, ticks, mosquitoes, and plantsseems reasonable; taking appropriate steps to gain an appreciation of the diversity and patterns of geographic distribution of othersespecially those of ecological or economic significance, such as fungi, nematodes, mites, and selected groups of insectsalso seems reasonable. The simple fact is that if we do not do so, we shall never have an idea of how many species there were or where they existed; we shall certainly be less able save them over the coming years.
It will be necessary for the industrialized countries of the world20% of the world's population with 80% of the wealth, about 90% of the scientists and engineers, and 20% of the biodiversityto recognize that the world's biodiversity is both our common heritage and the key to our future sustainability. By understanding it, learning how to use it sustainably, protecting it, and preserving it, we shall be making a priceless gift to future generations and acting responsibly in the face of one of the greatest challenges that ever confronted humanity. To the extent that this forum has contributed to that goal, it should be judged a success and a helpful building block along the way to a sound and sustainable future.