World Book Encyclopedia Presents Earth in the Balance rectrectrect
An Interview with Peter Raven


Peter Raven, a noted botanist and expert on the rain forest, explains how Earth's biological diversity is being threatened and describes what ordinary people can do to help solve the problem. Raven is the director of the Missouri Botanical Garden and the Engelmann Professor of biology at Washington University in St. Louis.   (World Book photo by Tim Parker.)

PHOTO: Peter RavenScience Year: As a distinguished botanist known for your interest in tropical rain forests, you've dedicated much of your life to educating people about the threats to Earth's biological diversity or biodiversity, the terms scientists use to describe Earth's rich variety of plant and animal species. By now most of us realize that animals such as rhinos, tigers, and spotted owls are in danger of becoming extinct. What else do we need to know?

Peter H. Raven: First, that organisms all around you--not just the tigers of the world--are facing extinction. For instance, botanists predict that nearly 800 plant species in the United States may become extinct during the 1990's unless we take steps to protect them. So you should understand that the problem isn't just that a few large and well-known types of animals are being killed off. Between 20 and 25 percent of all the species on Earth may disappear within the next 30 to 40 years.

The cost of rain forest destruction

SY: Why do you think so many organisms are at risk?

Raven: It's simple: Human beings are breaking down the habitats of plants and animals across the planet. Earth no longer has any unoccupied frontiers, and every inch of the planet's surface is affected by human activities. You can see this most clearly in Earth's tropical rain forests--which are found in nations such as Brazil, Zaire, and Indonesia. These forests contain an almost unbelievable diversity of life. About two-thirds of the world's species make their home there. But people are destroying the rain forests so rapidly that only small patches may be left in 60 years.

SY: What's the cause of this destruction?

Raven: The short answer is that the populations in many of the nations that contain rain forests are growing so rapidly that people must exploit the resources of the forest for short-term gain. Actually, the problem is that, on average, 40 percent of the people in these countries are less than 15 years old. Most of the people are choosing to have smaller families. But because the populations are so young, a tremendous number of individuals are reaching childbearing age each year. As those young people start having children, the population rate soars. The result of all this is that many of the people are living in poverty, and up to a third of them are malnourished. These people have an immediate need to use their forests for economic gain. They do this by cutting trees for lumber or clearing land to grow crops on. In addition, the forests are often cut for profit, without considering the region's long-term or general benefits, just as in the United States.

SY: When North America was being settled, immigrants cut down forests for lumber and to bring land into cultivation. Is that different from what individuals are doing to the rain forest today?

Raven: The effects are not the same, because clearing land does greater damage to the rain forest. Most of the soil in rain forests lacks the fertility of soil in temperate forests such as those in the United States. Only one or two years after a patch of rain forest is cleared, the land is barren. The rain forest plants cannot become reestablished, and the people must clear yet another patch of forest to get usable cropland.

Problem likely to worsen

SY: The rate of rain forest destruction appears to have slowed since the mid-1980's. Do you think the overall loss of biodiversity may soon cease to be a problem?

Raven: On the contrary: It's likely to get worse in the decades to come. The problem, after all, is that human beings are putting too much pressure on their environment. Imagine what will happen as the global human population doubles--as it's expected to--before leveling off at 10 billion or more in about 100 years.

SY: As you know, not everyone agrees that an increase in the human population will by itself lead to ecological disaster. A few economists, for example, propose that a larger worldwide population means more minds at work to solve any environmental problems that come our way. Why do you feel that this view is wrong?

Raven: The loss of one-fifth of the world's topsoil, the pollution of the atmosphere, and the loss of biodiversity--all these things show clearly that even now we are not managing the world in a way that we can sustain. There is no way that adding still more people is going to make these problems easier to solve.

An ethical practicality

SY: Why do you think it's so important to protect Earth's biodiversity?

Raven: To me, avoiding the destruction of so many of the other organisms in the world is the right thing to do from a moral, ethical, or religious point of view. As far as we know, the living things that share the world with us are the only living things in the whole universe. That alone ought to give us a respect or reverence for life. It ought to make us want to avoid driving the species into extinction permanently.

SY: Is the issue purely an ethical one?

Raven: Not at all. There are scientific and practical reasons to protect biodiversity as well. For one thing, having a rich array of organisms on Earth is like having a well stocked storehouse. Individual organisms provide most of the things we use to support ourselves--our food, the wood we use for shelter, the fibers for clothing, the natural compounds we use as drugs. We can draw on these stores to sustain us in the future. If Earth's average temperature rises due to global warming, for example, we may need to find tropical plants to replace crops now grown farther north.

Unfortunately, in many cases we have no idea what wonderful, beautiful, and useful creatures are disappearing forever. More than 85 percent of the organisms we're about to lose are unknown to science. We know next to nothing even about those we have named--a single feature of the species, a place where it's been found, or a very brief description. This helps explain why many scientists find the loss of biodiversity so distressing.

SY: The most common argument for protecting diversity is one you just mentioned--the potential use of organisms as sources of new drugs. Is it the most important reason?

Raven: It is important. Did you know that the 20 best selling prescription medications in the world are compounds produced by living organisms or modeled on compounds produced by living organisms? One of the most recent discoveries is taxol, a promising new cancer drug that comes from the bark of the Pacific yew tree. There are many other examples. For instance, drugs used to treat childhood leukemia are extracted from the rosy periwinkle.

Yet that's only one practical reason to protect biodiversity. Another is that collections of living things provide what scientists call "ecosystem services"-protecting soil from erosion, influencing the characteristics of the atmosphere, transforming energy from the sun into food energy, shaping local and regional climates, and other functions. Because prairies, rain forests, and other ecosystems do these things, Earth is a suitable place for us to live, and the planet operates as a self-perpetuating system. Without them, we simply couldn't survive.

Global responsibility

SY: You bring up one of the reasons many people are deeply concerned about the loss of the rain forests. Not only do the forests contain great biological diversity in the form of millions of species, but they also provide the ecosystem service of removing massive amounts of carbon dioxide from the atmosphere. This gas, a by-product of the combustion of fossil fuels, has been linked with the potential warming of Earth's climate. Does it seem to you that the health of the planet as a whole is now at the mercy of the tropical nations?

Raven: Actually, the planet is at the mercy of the industrialized nations as well. Those of us who live in the United States, Canada, Great Britain, and the other developed countries--which together account for only 23 percent of the world's population--use about 80 to 90 percent of the resources that support life on Earth. We're really having the major effect on the stability of the biological world.

SY: How so?

Raven: We're the ones who have released into the atmosphere tremendous amounts of compounds called chlorofluorocarbons, which are eating away at the ozone layer that blocks harmful ultraviolet rays from the sun. We're the ones who burn most of the fossil fuels and pump most of the carbon dioxide into the air. And we must share the responsibility for destroying communities of plants and animals.

Natural versus human caused extictions

SY: There's nothing inherently "unnatural" about vast numbers of species becoming extinct, however. In fact, there were a half-dozen or more episodes of mass extinction long before humanity's time on Earth. Could it be that today's extinctions are no different from those earlier mass extinctions?

Raven: I see tremendous differences. For one thing, this is the first major extinction in the history of the Earth that is caused by the activities of a single species--ours. It may also kill off more species than did the last mass extinction, which occurred about 65 million years ago. Many scientists think that a huge asteroid hit Earth at that time, casting up a cloud that darkened the sky for many months. This extinction killed off the last of the dinosaurs along with many other organisms. Now, as far as we can tell from studying the fossil record, the number of species in the world has been increasing steadily for the past 65 million years. We may now have an all-time high number. Losing 20 to 25 percent of them within just the next 30 to 40 years will mean that this extinction could easily kill off more species than the last one.

SY: It's true, however, that none of the episodes of mass extinction caused irreparable harm to the Earth. The planet's biodiversity, along with the ecosystem services you talked about earlier, have always been able to recover.

Raven: But not very quickly. It took more than 10 million years for Earth to recover from the extinction that killed the dinosaurs. That's a tremendously long period of time, especially when you consider that our species has been around for only a fraction of it, and that agriculture, for example, is only about 11,000 years old! The planet will recover from the loss of biodiversity, but whether we will or not is another matter.

SY: So people and dinosaurs may end up having a lot in common?

Raven: Indeed--except that dinosaurs could not reason about the world around them, while we have large and complex brains and are supposed to be thinking about what's good for us and taking action based on that. The human brain is the most complex and marvelous product of evolution in many ways. It gives us the ability to understand the nature of our dependence on the natural world. We ought to be using our brains to devise a way to prevent another mass extinction.

Preventing mass extinction

SY: You and one of your colleagues, the well-known biologist Edward O. Wilson, have created the framework for such a system.

Raven: Yes. We feel very strongly that there needs to be a world plan for learning about biodiversity and then a mechanism for managing it.

SY: How would that be accomplished?

Raven: First, scientists would learn about the better known groups of organisms as rapidly as possible. These groups include flowering plants, animals with backbones, and butterflies. We can use our knowledge of those species to calculate the overall biodiversity of the world. Then, during the next 50 years, scientists would try to learn about the other groups of organisms. In the end, we'd have a pretty good outline of the 10 million or so species on Earth. At the same time, we should be conserving Earth's biodiversity. The easiest way is by creating new parks and reserves, but if the areas where certain species live are being destroyed, then we've got to bring the organisms into zoos, botanical gardens, or seed banks.

SY: What do you think about the more fanciful solutions to the problem? For example, do you envision genetic engineers creating new species to replace those we're losing?

Raven: Every species on Earth is a unique product of 4 billion years of evolution. The idea of replacing such a species with one we've concocted is wrong for aesthetic or ethical reasons. Just as an individual human being is not a string of DNA but rather a unique person, so an individual species is more than a collection of genes doing a job.

Besides, we could never replace the losses of whole communities of plants and animals. Scientists first transferred genes from one organism to another fairly recently--in the early 1970's. Imagine the impossibility of trying to put together whole organisms out of strings of genes that we made up, and then somehow grouping those organisms together into communities that would produce something as complex and self-sustaining as a prairie or a rain forest. Remember, we barely understand how existing organisms function in natural communities or ecosystems. So the notion is crazy.

What genetic engineering can do is help tremendously in making human altered communities more productive, taking the stress off natural ecosystems. That is, if we could make plantations more productive by improving the growth rates of individual kinds of trees, then we might not have to cut down the ancient forests in the Pacific Northwest--thus keeping the area beautiful and preserving large amounts of biodiversity. Such techniques applied to farming could also make crops more productive, which would help us avoid destroying more rain forest to get new farmland.

The problem of poverty

SY:Wouldn't developing nations benefit greatly from this kind of technology?

Raven: Of course. Unfortunately, the industrialized countries have 94 percent of the world's scientists and engineers, and most developing countries have virtually none at all. So fostering scholarly interchanges and building institutions are extremely important for adding to the scientific and technical capabilities in developing nations. With our vast pool of scientific talent, the United States has an enormous contribution to make in that area. And such contributions are entirely in our own interest, because the better equipped these nations are to deal with their problems, the more likely they'll be to act in ways that benefit all of us.

SY: Do you think it's possible to address the loss of biodiversity without dealing with the poverty of many tropical nations?

Raven: No, I don't. Here's one way of looking at the problem: People who live in developing nations--77 percent of the people in the world--have 80 percent of the world's biodiversity but only 15 percent of the money.

SY: That fact has prompted so-called debt for nature swaps, arrangements in which industrialized nations forgive the international debts of developing nations. In return, the debtor nation agrees to protect its tropical forests, for example, by creating national parks. What do you think of these swaps?

Raven: They have limitations. Some nations, for example, are too poor to start creating national parks even if a debt is forgiven. But the industrialized world does hold the developing world in an economic stranglehold. I would be for abolishing developing nations' international debts tomorrow, because anything that would stop or even slow down the flow of money from poor nations to rich ones would help solve many of humanity's problems--such as the fact that 1.5 billion people live in absolute poverty and 700 million people are starving or severely malnourished. Eliminating the poverty would give us a chance to nurture more of the human talent in the world for solving our other problems.

SY: How about encouraging private industry to step in? In 1991, for example, the pharmaceutical firm Merck paid $1 million to a Costa Rican institute for the right to cooperate with Costa Rican scientists in "chemical prospecting" for new drug compounds in species native to Costa Rica.

Raven: Such arrangements are highly desirable. Unfortunately, extremely poor nations such as Burkina Faso or Burma are not going to be able to make million dollar deals of their own, because they don't have the means to manage their resources the way Costa Rica has. Also, it's simply not logical to rely on private companies to make everything all right. It's like the idea that charity or volunteers can solve any problem--something a lot of people in the United States have been saying for the last decade or so. If everyone were charitable and willing to be a volunteer, then that would be marvelous. But, realistically, the most efficient way to provide large amounts of money for any purpose is for people to voluntarily tax themselves. When you're talking about major social problems, we can never deliver more than a small amount of what's needed through volunteerism or private industry. Those things can make important contributions, but only government intervention can deliver the goods.

How citizens can help

SY: Not all young people will want to pursue a career in environmental protection, but many of them may be interested in protecting biodiversity. What would you advise them to do?

Raven: The most important thing is to learn all they can about the environment. You cannot lead an informed life as a citizen of the future, making good decisions for yourself, your company, or your family, if you don't understand global ecology. Understanding will make you a better citizen and will motivate you to take action when it's needed.

SY: Are there some concrete actions readers can take?

Raven: Yes. First, we can all look at our level of consumption and think about how we can lead better lives by using less. The U.S. population comprises 4.5 percent of the people in the world, but we use at least 25 percent of everything that the world produces to maintain our standard of living. Per person, we use up more metals, plastics, wool, and food than any other nation. We waste more energy per person, and we produce more garbage per person. I urge families to discuss how they can use their cars less, waste less food, and use less electricity. That doesn't necessarily mean lowering their standard of living. It may mean turning to new, energy saving inventions or technologies. It definitely means being more thoughtful.

Finally, we have to take seriously our role in the political process in the United States. It's completely foolish to say that a mayor, governor, or President doesn't pay as much attention to the environment as we want him or her to do. After all, you and I are responsible for electing representatives and telling them what issues are important. Too many of us sit around and wait for somebody else to take action. We need to give our elected representatives input so that they'll do what we want.

Balance--the ultimate goal

SY: And what should be the end result of all these efforts?

Raven: Bringing ourselves into balance with what the world has to offer. If we can find a population level that our single, common, planetary home can support, and if we can learn how to manage that planetary home so that it continues to sustain us, then we'll be able to save whatever biodiversity is left at that time. We'd better hope we save a good sample of it, because only biological diversity is going to allow us to continue to exist and improve our lives in the future. That's why blowing away 20 to 25 percent of all the species on Earth ought to be seen as an insane act.

SY: Do you think we'll achieve the goals you've described?

Raven: I have enormous faith. I'm very optimistic about the power of individual human beings. That optimism makes me want to take action and get other people to do so, too. Whatever is left of life on Earth in 100 years will depend directly upon how you and I accepted our responsibility to the planet. Like it or not, we're in the position of Noah just before the flood--looking at an upcoming extinction of enormous proportions and realizing we alone are responsible for saving as many creatures as we can.


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