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The Habitable Planet: A Systems Approach to Environmental Science 

Looking Forward: Our Global Experiment Interview with Edward O. Wilson

Interviewer: Tell us about your early life, when you first realized you were going to be a naturalist.

EDWARD: I became a naturalist probably at the age of 9. I became so devoted to it that I decided even at early as that, 9 or 10, that I was going to be an entomologist when I grew up. I just loved bugs. Of course, most kids are interested in them. Kids do have a bug period. Some never grow out of it. And I was one of those that never did. The interest in insects was compounded by a fascination with wild environments. As a little kid I read about these places in the world where explorers go and naturalists have adventures and discover beautiful butterflies and beetles and so on. At that time we lived in Washington, D.C. I had the added advantage of being close to the National Zoo, so close to our apartment in Washington I could walk over to it with my butterfly net and collect butterflies in Rock Creek Park around the zoo and spend long hours in the zoo. That’s the way I wanted to spend my life. And that’s the way I feel today. I just never changed.

Interviewer: What is the feeling that you get when you go into a tropical forest?

EDWARD: The feeling that I have when I walk into a tropical forest, especially the extremely rich rainforest of the continental areas, is probably very different from what others get. I walk in as a scientific naturalist, as an entomologist, as a specialist on ants. I have a very specific search image, that is, I start looking for certain kinds of insects, usually ants, because that’s what I do my research on. And, of course, in a tropical forest, I’m immediately rewarded. I often don’t go more than 100 yards in from the edge to become completely occupied with what I’m doing. On the periphery of my image of searching is a never diminishing sense of wonder about the variety of life that is there. And the evidences of it having been built up over millions of years into a multi-tiered architecture of living forms. It’s commonly said that rainforests have three levels: an under story, a mid level of trees, and then a towering upper story that has most of the canopy that captures sunlight. And each one of those levels has its own life forms, but when you explore that, as you’re able to explore it, then that’s just the beginning because then there is the brown level. The level of soil and litter, enormously rich fauna and flora of bacteria, fungi, and other organisms responsible for the decomposition of all that vegetable matter that falls down on it when branches are broken or leaves die or fall off. The combination of those four levels in a highly productive, one might say, almost over-heated system is awesome to the naturalist and to the tropical biologist and contains within it the explanation of the tropical rainforest which, although they cover only six percent or so of the earth’s land surface, are believed by most specialists to contain a majority of the species of plants and animals in the world. So you are entering a treasure house when you go into a tropical forest. I know that’s not the way most people see it. They’re looking for parrots and monkeys. And they’re a little scared of maybe encountering a snake, although they rarely do. Or maybe something like a jaguar, but eventually everyone could come to appreciate the tropical rainforest in much the way that I do.

Interviewer: One of our programs is focusing on Stewart Davies, who is making catalogues of trees in twelve different areas around the world in forest research sites. Would you make a connection for us between this incredibly rich ecosystem as a whole and the trees? What is the role of the trees?

EDWARD: The role of the trees in the tropical rainforest is pretty much the same as in forests in other parts of the world. That is, they have come in a forest environment to dominate the capture of the sunlight energy. So in that sense they are super competitors. If there is enough moisture and the soil conditions are right, the trees and shrubs will grow. The woody vegetation will dominate. So that’s one aspect of them. You wouldn’t think of them as having a particular role in the ecosystem that makes them distinct from grasses in a grassland or even lichens on an Arctic tundra. But the fact is that having created a spectacular three-dimensional structure by being dominant, where trees and shrubs can be dominant, they enormously enhance the variety of habitat available to herbivores, to insects that eat plants, both for food and also for shelter. And upon the insects then, one can base a growing number, a large number of other creatures: spiders and other insect predators and larger animals; lizards, birds, mammals, that can feed on the insects and on the birds and then on the fruit of a wide variety of kinds, so that the forests are able to control photosynthesis, a good part of it, but at the same time they’re providing a home and a source of energy for an immense variety of creatures that depend upon the plants. And that is one of the explanations for the great diversity found in forests.

Interviewer: What about trees in a tropical forest?

EDWARD: The trees in a tropical forest are multi-layered. We speak of them in rather hazy terms, but in a manner that is illuminating as being in three layers, but certainly in multiple layers. Let’s say three. Roughly the under story, which is about the height of a person or a little bit more, and then the middle story of trees, of somewhat small size. And then the towering trees of the upper canopy, that create the upper canopy. That division into layers provides a wide variety of niches for other organisms that include epiphytes, like orchids, gasneria, and so on, and the creatures that live in them and on them. It includes even space at different levels and degrees of solar energy capture of organisms that live only on the leaves on what are called epiphylls, little miniature woodlands of moss and lichens. In those are other creatures or small insects and mites and so on, found only in those epiphylls. You get stacked, one upon the other, different levels of energy in the energy flow, and niche differentiation so that species can specialize to a very fine degree. This is made far possible, especially by the structure of the tropical rainforest. It’s part of the reason why rainforests are, in fact, as far as we know, the repository of more than half of the plants and animals species on earth.

Interviewer: Why is it important to start by looking at the number of the species of trees in trying to assess the health of an entire ecosystem?

EDWARD: Very generally we expected from theory, from theoretical calculation, and now have confirmed by experiments, both in the laboratory and the field, that the more species of plants there are, the more stable the environment, the more productive it is, and the greater the number of niches it can provide for animals and other kinds of organisms. There’s a common sense element to this: the more species you have, the more likely you’re going to have an insurance policy for the whole ecosystem. In other words, let’s suppose that one tree species is very important for the functioning of the ecosystem. It can be something as in, for example, a mangal forest, which has an obviously very small number of species. Or it can be a rainforest where just a small number of species provide a large part of the canopy and are responsible for much of the animal diversity. If one species becomes drastically reduced or extinct locally, if you have many species, then there are other species that can fill in. This is known as the insurance policy, or the insurance principal of tropical and other forests.

Interviewer: Why should we care about the health of the tropical forests?

EDWARD: I would argue very generally we should care about the health of any ecosystem, yes, even the very sparse ecosystems of some deserts, or parts of the Arctic or Antarctic, but I think we need to pay a special attention to the tropical forests because that’s where most of the diversity of life is on earth at the species level. And we should look at it not just for the economic return that the close study of all these species and development of many kinds of products that we can anticipate coming from their study provides. But also because of the stability of the regions in which they live. It’s been estimated, for example, that in the Amazon a very large percentage of the rainfall is generated by the forest itself. The rainfall keeps the Amazon moist. So if you cut back too much of the Amazon forest, then you might very well reach a tipping point in which the remaining forest is not receiving enough rainfall, and it too will fade away, and with it can change the entire climate, and probably not favorably because most of the soils there are poor. So we need those forests to hold the cap on the existing world of land environment. We don’t know what crazy and destructive directions local climate and soil conditions and rainfall and so on, will move in if we destroy too much of the forest. But then, you know, there’s the spiritual reason. For heaven’s sake we’re talking about most of the creation in these forests! If we measure it, say, by different kinds of plants and animals and microbial organisms, do we really want to see these forests continued to be destroyed? The species that are in them are often millions of years old and have taken almost unimaginably long periods of time to evolve, to be adapted to one another, and to create unique genetic combinations and unique physiology and unique life cycles, and so on. Every time we allow one species to go extinct, and they’re going extinct at a pretty high rate in the tropical forest today, we’re erasing a million years or so, maybe a little less, maybe a lot more, of genetic evolution and the unique products of that evolution. We’re losing it often without even knowing it was ever there.

Interviewer: Can you draw parallels between the human impact on tropical forests and the human impact on coral reefs?

EDWARD: Very similar. Coral reefs have been called the rainforest of the sea, and probably they do indeed collectively have more kinds of organisms, mostly animal and symbiotic algae that live in the coral combined, but lots of other life forms, microscopic especially. And so the coral reefs of the world are like a rainforest, and an especially rich and precious resource. They, too, are disappearing due to human action from action change; they’re overheating corals, and that apparently causes bleaching. But also it’s just outright destruction from pollution, from dynamiting to collect fish and from building material of all things. It’s like dynamiting Notre Dame to be able to get enough rubble to build a supermarket nearby. It’s awful. But that’s happening to the rainforest at least the same rate worldwide as it’s happening to the tropical rainforest.

Interviewer: What’s your feeling about our whole fishing industry in terms of the riches in the ocean?

EDWARD: I think it’s a source of astonishment to the world to wake up maybe as early as a couple of decades ago and learn that we really could fish the seas out. And that is what we have done. We have driven down the major food fishes of the world drastically, so the average size of the fish being taken in is dropping. We kill them off before they can grow up and be big! And, of course, some fish species have been driven to what’s called commercial extinction, that is, they’re no longer producing sufficient income for the fisherman who specialize on them to pay off. Others are being relentlessly pushed down to that level, and the extinction of some species is imminent. In one case that I know of, the barndoor skate, a huge ray-like animal that reaches six feet across, is extinct. It’s been wiped out of its habitat on the North Atlantic as a by-catch. It wasn’t hunted deliberately, but these fish get caught in nets and they have been reduced apparently to extinction. So it can happen. We are drastically changing even the open sea as well as the sea bottom, particularly the shallow sea bottom, in ways that are going to be difficult to recover. Bottom trolling is roughly the equivalent of, not only say, cutting a forest, but plowing the land. And a large part of the shallow, or continental, shelf bottom has been altered by dragging nets over it. This is the destruction of the places where the species not only live, but also they spawn. So we are destroying them and we’re destroying the cradle that produces them. And furthermore, our removal of wetlands, marshes and mangal swamps especially, which are the birth places and breeding areas, the nursery areas for young fish and other marine life, are being destroyed at such a rapid rate that this is going to have a big impact not only locally where they are, but also out to sea and along the ocean floor.

Interviewer: Why is it important to know what we’re doing in terms of this kind of destruction? Why do we have scientists going out and counting species and looking at how many have disappeared and measuring the rainforest?

EDWARD: Well, if we don’t know what’s there, how can we manage our own affairs in a way not to destroy the base of our life, which is a healthy environment, a healthy living environment, especially. To not know what the species are and to try and to plan ways of making use of the biodiversity in these ecosystems as well as protect them for long-term sustainability – we have to know what they are. There’s a close parallel, it’s like trying to do medicine by not knowing what people look like inside. You can do it with witchcraft and luck, but you’re not going to get very far.

Interviewer: What do you think the future holds in terms of the environment, looking 25-50 years from now into your crystal ball?

EDWARD: I’ve often said that I’m cautiously optimistic and people immediately challenge me and say, how could you be any kind of optimistic. And my answer is reading trends and also having some faith in human nature. As Abba Eban, Israeli foreign minister, once said in the middle of one of these Mid-east wars, and it’s my favorite quote, “When all else fails, men turn to reason.” So I have a lot of faith in human beings and their desire not to destroy the world, and a lot of moral ineptitude, it should be remembered, is due to poor planning rather than innate wickedness. I think people are innately good, but they tend to be terrible planners so they get themselves into situations when they do bad things. I believe that’s the situation we’re in right now in the environment, so I say that the signs are, we are waking up, the world is waking up. People around the world are now generally aware of important environmental changes, led by climate change. That’s accepted in most places. And they are aware that species are going extinct at an accelerating rate. And they understand that it’s not a good thing if we destroy the rainforest and coral reefs. In fact, it’s a very bad and dangerous thing. And this rising awareness, I think, can be read as a trend, which is a source of optimism. The question is, will we wake up? Will we reach a tipping point, and I hope there will be a tipping point where this becomes part of the global ethic in time to avoid real catastrophe in terms of climate change that will affect all of us, and in terms of mass destruction, possibly up to half the species on earth, say, by the end of the present century.

Interviewer: Is there a danger that we’ll wake up and it will already be too late? Is that human nature?

EDWARD: The question is, will we wake up to the environment crises and actually mobilize ourselves and our resources to stop it, slow it anyway, and then eventually stop the deterioration of the environment. And note, it’s not just a matter of achieving this, of curing an ongoing pathology, human environmental pathology. But also it can be a very substantial source of new wealth. As we learn more about life on earth in particular, we have more sources of wealth available to us. And as we develop the technology to preserve the environment and turn the environment into a sustainable system, then a new technology and new sources of wealth will be available from that. That’s always been the case with human economic growth, in the industrial age particularly, and now the post-industrial age. So I think we have a good chance of catching it in time. I’m particularly interested now, personally, in enlisting religious believers. I think we have — I mean by we, the secularist scientists who have provided the information of what’s happening and generally have been the leaders in raising the alarm about what’s happening — they have done so as a minority without really taking the right steps to enlist engagement of the rest of the people. It’s an amazing fact to me that there are 30 million members of the National Association of Evangelists in this country and then large numbers of other evangelicals, and then still larger numbers out there of people of other denominations in the Judeo-Christian realm, particularly in America, versus 5000 members of the combined three largest secular humanist organizations. It’s the secular humanists who seem to be the cutting edge for the most part for our environment. My belief is that maybe we should be looking for an alliance here. Stop worrying about who knows about science, stop worrying about what the differences are in religious interpretations, and the culture wars over evolution and other religion versus secularism disputes. Put that aside, for heaven’s sake, and realize that science and religion are the two most powerful social forces in the world. That the vast majority of Americans, for example, are intensely religious, or are at least comfortable with religious beliefs, and guide a lot of their lives by religious beliefs directly or indirectly. And try to understand that these are not dumb people. They are very smart people. It’s just that they have a different worldview from the secular scientists. I think they’re fundamentally environmentalists. They want a clean, healthy environment for themselves, I’m sure, and their children and their grandchildren. And I’m sure too, that if you just put it to them plainly, yes, they don’t want to see the creation, that is, the biological diversity of the world wiped away carelessly. And if we could get together on that one ground of paying attention to the living environment and doing something really as a people to solve the problem, we would solve it.

Interviewer: We have a few small bright spots on the horizon which we can talk about, for example, the Yellowstone ecosystem – the Yellowstone National Park and its surrounding areas – where they reintroduced the wolf. Would you talk about how, just in terms of an ecosystem, how adding back something like the top predator that was taken away, can open up all these possibilities for everything else and bring back balance?

EDWARD: Introducing a wolf brings the ecosystem back, since it’s a top predator, to something like its original balance in the sense that now the herds of elk and other herbivores are cut back and then we know that they can be at least in a rough balance, with fewer herbivores. Then, with the herbivores kept in control to some extent, you have an improvement in growth of a lot of plant species that were otherwise being trimmed back to very low levels. So a single species sometimes, can make a huge difference whether it is present or absent. It should be borne in mind that those ecosystems in the Yellowstone and surrounding regions evolved for tens of thousands or hundreds of thousands of years to have a wolf in them, a wolf species in them. So you take it away, then you’re in a condition that has not existed before, and you’re going to throw it out of balance. An even better example, one that’s more spectacular, is the sea otter, off the Pacific coast of North America. The sea otter was hunted down to near extinction because its fur is very valuable. When that happened, it turned out that we had explosions of the sea urchin population because sea otters feed to a large extent on sea urchins, these little spiny creatures that are all over the bottom of the ocean. And because now there were so many of these little invertebrate animals on the sea floor, we witnessed the destruction of the kelp beds, the natural vegetation, pretty much like wolves in the Yellowstone. So that one species being cut back by human activity eliminated a lot of the kelp forest, and large numbers of species of animals that live in them along much of the Pacific coast.

Interviewer: Another example we mentioned is the sea turtle and sea grass.

EDWARD: There are a lot of examples. You don’t have to look far to find many examples of what we call keystone species, that is, species that if removed or in the case of invasive species, insect pests for example, can change an entire ecosystem. That’s why we need to know a lot about the ecosystem and the species in them and be able to monitor and hopefully even predict what happens if we take one out or put one in.

Interviewer: What can we learn from the past that will help us now and in the future?

EDWARD: In evaluating environmental change, historical and even archeological records are invaluable. That’s the only way that we can find direct evidence of what has happened in the last few centuries or even in some cases, all the way to a thousand years. For example, thanks to historical records, we know now that as recently as 2000 years ago in the Roman era, the Mediterranean area was much more forested. You could walk from Carthage to Alexandria in a shade of trees. North Africa was not the searing desert it is today; it was a savannah with wild animals of the kinds you now find in East Africa, including elephants and lions and all these things that were captured and shown off in the Roman Coliseum. And go over to Hawaii – – now that’s history – – go over to Hawaii and you discover that before the first Polynesians arrived, that’s the first humans who arrived around 400 A.D., that there was something like 125, maybe 150 species of birds native to Hawaii. And they were spectacular. There was a flightless ibis, there was a Hawaiian eagle, there were giant goose-like birds, and a wide variety of other birds including, particularly, the beautiful honeycreepers. We know from archeological records that they were there, that is, going back a few centuries or millennia, and that they disappeared pretty promptly, a large percentage of them, when the Polynesians showed up. And we know that many more disappeared after the Europeans and other colonists came in starting in the 18th century. Those records tell us not only the extent of the damage of human activity, but they tell us quite precisely which species disappeared. We know those species only by remnants, sub-fossil, the material in the archeological excavations.

Interviewer: What is the importance of the places that we’re saving to the future of mankind?

EDWARD: Reserves of natural environments -natural environments of the world – are shrinking fast so we’re setting aside some and we need a lot more. We need to ensure that there are wilderness reserves as well. For example, for tropical forests you can still have wilderness-size reserves in the Amazon, the Congo basin, and New Guinea. We need these for a variety of reasons: environmental stability, the economic potential of having a sustainable environment, and so on. But I think we also need them for the human spirit, and let me just put it in terms of a very fundamental principal that most people I hope would agree with. Humanity needs choices. Human beings — and this will be true down indefinitely into the future — humanity needs and deserves the choice of visiting natural areas in which the human species evolved, and to which we are more akin and spiritually attached than most people realize. If we completely humanize the world, then there is only that choice. If we leave these reserves and include wilderness areas in them, where you can enter and see the planet as it was before humanity began to transform it, then we have a choice. And we know from a mass of evidence that now includes psychiatric, post surgical recuperative care, trends in architecture, interpretations by historians, and on and on, that there is a very strong need for humanity to have natural environment. The wealthiest people in the world take note. They use a good portion of their wealth to be able to go to these areas and they have their own habitations there, in them or on the edge of them. We should allow humanity as a whole and humanity on into the future to have no less. As a simple precaution we should not let an irreplaceable resource, human resource if you want to call it that, the natural places in the world disappear. Because once they’re gone, they’re gone forever.

Series Directory

The Habitable Planet: A Systems Approach to Environmental Science 


Harvard Smithsonian Center for Astrophysics in association with the Harvard University Center for the Environment. 2007.
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  • ISBN: 1-57680-883-1