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Public Radio's Environmental News Magazine (follow us on Google News)

June 9, 1995

Air Date: June 9, 1995


Nature as Healer

Living on Earth host Steve Curwood explores the emerging evidence that surrounding oneself with nature can be a healing act, and that being cut off from nature can contribute to stress and even social conflict. This report is the second in a periodic series exploring the “Biophilia Hypothesis” of biologist Edward O. Wilson. (13:17)

Mite Makes Right: Biological Insect Control in Benin / David Baron

A tiny insect has saved Benin, Africa from possible famine. Scientists discovered and then imported a natural predator wasp to kill off mealy-bugs that were devastating the nation’s staple cassava harvest. David Baron of member station WBUR reports. (07:50)

Show Credits and Funders

Show Transcript

Copyright c 1995 by World Media Foundation. No portion of this transcript may be copied, sold, or transmitted without the written authority of World Media Foundation.

HOST: Steve Curwood
REPORTERS: Stephanie O'Neill, Jennifer Schmidt, David Baron

(Theme music intro)

CURWOOD: From National Public Radio, this is Living on Earth.

(Music up and under)

CURWOOD: I'm Steve Curwood.

We all love nature, but how important is it to us, really? New evidence suggests that being cut off from natural landscapes can increase stress, slow recovery from injuries, and threaten our sanity.

ROSZAK: Let me put it as bluntly as I, as we can. We have detached ourselves so much from the natural environment that it is wounding our mental health.

CURWOOD: Also, chemicals are out and benign insects are in, in a successful effort to prevent an African famine. The technology is effective and affordable.

NEUENSCHWANDER: You don't need foreign currency, foreign exchange, to import things. You do not need machinery, you do not need water and so on. This offers sustainable solutions.

CURWOOD: This week on Living on Earth. First, the news.

Environmental News

NUNLEY: From Living on Earth, I'm Jan Nunley. The first real test of the North American Free Trade Agreement's environmental provisions is underway. The Audubon Society's US and Mexican chapters and others want NAFTA's Commission for Environmental Cooperation to investigate the deaths of up to 40,000 migratory birds in Mexico's Silver Reservoir last year. Under NAFTA, the Commission must probe the incident and make recommendations to the US, Mexico, and Canada. The complainants also want the Commission's help to find funding for cleaning up the reservoir.

Scientists and environmental activists have compromised on a plan to measure global warming by broadcasting sounds across the Pacific Ocean. From Los Angeles, Stephanie O'Neill reports.

O'NEILL: Scientists from the Scripps Institution of Oceanography have promised environmentalists that they will spend at least 18 months studying the effects of human-generated underwater noise on marine life before proceeding with their climate research. Under the original plan, the scientists were to blast the ocean with loud sounds every day for 20 minutes every 4 hours. Critics feared the project would hurt marine mammals near the speakers and would disrupt feeding habits and migration routes. The compromise allows less frequent blasts, and it commits $4.5 million to the marine mammal study, which would be the largest such study of marine mammals by university scientists. The plan would also examine the effect of commercial ship noise on marine mammals. Under the $35 million study, which is funded by the Defense Department, scientists hope that by transmitting the sound through the Pacific Ocean they can measure subtle temperature shifts, as sound travels faster through warmer water. For Living on Earth, I'm Stephanie O'Neill in Los Angeles.

NUNLEY: Radon gas may be responsible for as much as 30% of lung cancer deaths among non-smokers in the US. That's according to a National Cancer Institute study, which also suggests the naturally occurring radioactive gas may cause 10% of all US lung cancer deaths. Researchers compared lung cancer mortality among miners who are frequently exposed to radon at work with their level of exposure to the gas. Based on those numbers, the epidemiologists estimate that nearly 14,000 people die from home exposure to radon every year. The EPA recommends that all homes be tested for radon.

This year's hurricane season may pose a high risk for US coastal communities. The periodic warming of waters in the eastern Pacific known as El Niño has kept hurricane activity below normal for the past 4 years. But researchers at the National Hurricane Center in Miami say this El Niño cycle has ended, and warn that more storms could hit the southeastern US. This year's first hurricane was spotted June 3rd, the earliest hurricane to arrive since reliable records began to be kept.

Recycling has gone on-line, thanks to a Washington-based company. The National Materials Exchange Network lets companies and consumers exchange materials they don't need any longer. From Seattle, Jennifer Schmidt reports.

SCHMIDT: The intent of the service is to encourage the recycling of goods that otherwise might end up in a landfill. All it takes to tap into the exchange is a computer and access to the Internet. The network is a little like a free version of the Classifieds. It's an organized list of unwanted materials available all around the country. A recent browse turned up more than 30 categories and an array of free items, including glass windows, computer components, even car seats. While not everything is being given away, Materials Exchange director Bob Smead says nobody is trying to make a huge profit by listing their products.

SMEAD: The majority of them are free or very inexpensive to avoid disposal costs. Our concept here is to be the garage sale on the Information Superhighway.

SCHMIDT: The Exchange also includes a Wanted section where companies or individuals that need products can advertise for them at no charge. For instance, a church has used the Exchange in hopes of finding free carpet. A day care center tapped into the network looking for kitchen sinks. The concept of the Materials Exchange is not new. For several years, regional exchanges have distributed free catalogues of listings to local businesses. But organizers hope having an Internet site and access to millions of people will encourage recycling across the country, or even across international borders. For Living on Earth, I'm Jennifer Schmidt in Seattle.

NUNLEY: Fifty years after the end of World War II, Britain is waging another battle against invasion by determined foes. But this enemy has four legs. A census by London's Chartered Institute of Environmental Health shows there are now 60 million rats in Britain. That's 2 million more rodent than human residents. Researchers say the rodent population bomb is aided by an increasingly litter-prone human populous on the sceptered isle. Scientists say the rodents are also stronger than ever, having developed resistance to common poisons.

That's this week's Living on Earth news. I'm Jan Nunley.

Back to top

(Theme music up and under)

Nature as Healer

CURWOOD: This is Living on Earth. I'm Steve Curwood.


CURWOOD: It's a universal human experience, that moment when the natural world takes away our breath with its beauty, its poignancy, its wacky inventiveness. It can happen on a hike, on a stroll at the beach, or with the discovery of a bird's nest in our own back yard. Nature has always struck a powerful chord in humans.

(Modem "deep space" electronic sounds)

CURWOOD: But in a world that's increasingly paved over and resynthesized, it's a chord that's sounding less and less often.

(Modem sounds continue)

CURWOOD: What does it mean when we're cut off from the natural world? Does it affect our mental health? Turn the questions around. What does contact with the natural world do for our well being? More and more researchers are asking these questions and finding some startling answers.

WILSON: I think the evidence is mounting that we are in great need of the remainder of life.

HEERWAGEN: I think the sense of pleasure that we can get from the environment probably has very profound implications for our well being.

ROSZAK: I think the biophilia hypothesis suggests that there is a level of the human mind or spirit that is linked almost genetically to the natural world.


WILSON: Biophilia means the natural, by which I mean hereditary, affiliation that human beings have and feel for the natural environment.

CURWOOD: That's Harvard biologist Edward O. Wilson, a great thinker who has won 2 Pulitzer Prizes. Professor Wilson says that because humans evolved in nature, we have an innate love of life. Not just human life but the whole natural order that nurtured us. Scientists often use Latin names, so Professor Wilson calls his notion the Biophilia Hypothesis: literally, the Love of Life. And humans, he says, need nature to thrive.

WILSON: That's not a new idea. It's been very much in the spirit of the times and the thinking of natural philosophers going back to Lucretius.

CURWOOD: What is new is that Professor Wilson and others exploring his biophilia hypothesis are looking for evidence that the human need for nature is rooted in our genes, which hold our deep memories that go back for millions of years. And they think they're starting to find it, in the way people respond to certain types of environments.

(Chamber music)

CURWOOD: Think, Professor Wilson says, of the gardens of the world.

WILSON: And here we have something that does run across cultures, from Babylon to Mesoamerica, back to the formal gardens of Europe and on to the exquisite gardens of old China and Japan.

CURWOOD: Think of the palaces and estates that people have built the world over when they have grand resources. They look remarkably like the African savannas, Professor Wilson says, where the great apes first came down out of the trees, stood upright, and turned into humans.

WILSON: The optimum environment appears to be upon a prominence overlooking parkland, that is, savanna-like environments with dots of trees and copses, and also overlooking water. In other words, the optimum environment is precisely what the rich and the powerful choose everywhere in the world, when they're able to make a free choice. In Manhattan it's a penthouse with a terrace, well-stocked with tropical plants and shrubs and overlooking the lake in Central Park.

(Chamber music continues)

CURWOOD: And simple back yards and public parks also serve those of us who aren't so rich as well. Central Park was built back when people were flocking to the highly unnatural factories and urban congestion of the industrial revolution. Its designer, Frederick Law Olmstead, suggested that the building of great public green spaces might be a self-preserving instinct of civilization. And indeed, researchers exploring the biophilia hypothesis, point to how city people rejoice in their back yard gardens and public parks as evidence of the deep human need for contact with nature.

HEERWAGEN: We are responding in a very old and an ancient way, I think, to current living conditions.

CURWOOD: Judith Heerwagen, an environmental psychologist at the Batelle Northwest Laboratories in Seattle, who is exploring how humans respond to different kinds of environments. In one study, Dr. Heerwagen showed people images of both natural and built landscapes. Her sample was narrow, but her findings were provocative. Her subjects almost always preferred the images of natural environments. Dr. Heerwagen thinks that evolution explains this preference for nature.

HEERWAGEN: We need to think of it in terms of what does this do for us? How does it help us survive? How does it help us live? I think that the sense of pleasure and well-being that we get out of nature comes from the very long evolutionary history of living in natural environments and having to extract information and resources from nature, so it had a lot of payoffs for us to be able to tell if an environment was safe or not, and if it had protection and resources.

CURWOOD: This emotional relationship to nature, Dr. Heerwagen says, is part of our evolutionary survival mechanism.


CURWOOD: And there's evidence that nature nurtures us, as well.

ULRICH: One category of influences has been broadly termed restorative influences.

CURWOOD: Roger Ulrich is a professor of landscape architecture at Texas A&M University. He studied the vital signs of people first shown a stressful movie, and then shown videotapes of either natural settings or urban environments without nature. There were clear differences in heart rates, blood pressure, and muscle tension. Compared to those who had looked at buildings and pavement, the group which watched the nature clip showed signs of lower stress. Ulrich has also studied the actual health outcomes and recovery rates of some US hospital patients, whose rooms look out on trees and grass, versus those who see only other buildings. And he says the patients with the natural views healed better.

ULRICH: Examples would be reduced need for pain drugs, fewer minor complications, say, develop following surgery that are thought to have a psychological component such as persistent headache or nausea. Blood pressure will decline. Muscles will become more relaxed. Brain electrical activity will change in such a way to suggest that the person is feeling more wakefully relaxed. Such restorative effects for hospital patients have been recorded in a study or studies using real patients, not in laboratories or simulated situations, in real hospitals, looking out real windows, for instance, at real nature, or real urban lacking nature. And these beneficial influences have been found.

CURWOOD: Like Judith Heerwagen and E.O. Wilson, Professor Ulrich believes what he's seeing are adaptive responses to evolutionary pressures.

ULRICH: After all, daily life for early humans was full of challenges and taxing experiences. So one is left with the notion that it would have been sensible to have the capacity to be restored from this experience, rather quickly. And that if we encountered an unthreatening, natural environment with the right characteristics, this should elicit a fairly quick onset restoration. This would be adaptive because it would help us conserve our physical and psychological resources, and we would be in a much better position to respond or deal quickly with a new situation.

(Trains pulling into a station)

CURWOOD: No one exploring the biophilia hypothesis suggests that if we have a genetic tendency which attracts us to nature, we can't live creative, healthy, and productive lives in civilization. But what happens when we're completely cut off from nature? What if we're locked up in a modern city without a back yard or a green park to take refuge?

ROSZAK: Speaking as a historian, I can assure you that cities have never been as inorganic, as ecocidal, as they have become in modern times.

CURWOOD: Theodore Roszak is a professor at the University of California at Hayward.

ROSZAK: In times past, the line between the city and the country was much, much more fluid and loosely drawn. If nothing else, cities were a lot dirtier. But at the very least, people were closer to the stuff of life.

CURWOOD: Recall what Judith Heerwagen of the Battelle Lab says about how the sense of pleasure we get from contact with nature may be linked to how our ancestors used to find food and shelter. If certain natural cues help make us feel safe, Dr. Heerwagen says, then an environment without them might do just the opposite.

HEERWAGEN: I think that in environments where these are missing, the signal that it's sending out is that these places are devoid of many things that we value. They're resource-poor, they're not cared for. They have a sense that they're not livable.

(Construction noises: Drills, etc.)

CURWOOD: But of course people are complex creatures, and we do live in such places. Today, billions of us spend our lives surrounded by asphalt, glass, cinderblock and sheet metal. And some of us that do have green space outside rarely bother to look. Dr. Heerwagen believes that this constant separation from nature can cause people to become unsettled, stressed out, anxious. Theodore Roszak, who has been a pioneer in the field of eco-psychology, is more direct.

ROSZAK: Let me put it as bluntly as I, as we can. We have detached ourselves so much from the natural environment that it is wounding our mental health.

CURWOOD: Professor Roszak believes that symptoms of this kind of detachment, these wounds, are all around us. An example, he says, is the view of the natural world as being just so much real estate to be bought and sold, or resources to be extracted. Professor Wilson, meanwhile, wonders whether another symptom might be the breakdown so common in society today.

WILSON: I believe it is true that what we recognize as social pathology, the sharp divisions among people, the increase in crime, rioting, homelessness, indifference of people to the needs and suffering of other people, does arise in environments where human beings are most separated from the environments in which they originated.

CURWOOD: So too many buildings, too many people, too many cars, not enough trees, not enough open space - this in part may be what's tearing apart our cities?

WILSON: There's no question that urban environments are stressful. There's no question that people are more prone to violent behavior, to indifference toward their neighbors, if they're forced to remain in a very unnatural, crowded urban environment.

CURWOOD: It's all still very new, this idea that a need for contact with nature might be a fundamental part of our nature. But if it is true, E.O. Wilson and others exploring the biophilia hypothesis say that when we take care of nature, we are in fact taking care of ourselves, and our own abilities to survive and thrive. On a grand scale, this means saving species and whole ecosystems. But on a daily basis, it may be just as important, if not more so, to have nature at home, at work, and in our communities. Keeping a few geraniums by our front door and keeping the oak trees on our street may help us keep our sanity. Again, Dr. Judith Heerwagen.

HEERWAGEN: We may think this is trivial, and if we were out, to go out and measure the effects, they probably would be kind of small given all of the other things going on in people's lives. But I think that there's more and more evidence that these small pleasures in our life, the ability to sort of just sit outside and watch the birds or listen to the birds, to see the trees grow, to see them bud, to see them flower. These kinds of things really are good for us; they do kind of free the mind in a way that we're just beginning to realize is really important.

Back to top

(Chamber music continues.)

Mite Makes Right: Biological Insect Control in Benin

CURWOOD: Chemical pesticides have contributed to tremendous growth in food production in this century, but not without causing other serious problems, including contaminated groundwater, decimated wildlife, and human illness. Today, many farmers are trying to use pesticides more sparingly and are looking increasingly to natural solutions. In Africa, scientists say they are on the verge of winning the war against 2 devastating crop pests that put millions in danger of starvation. And they're doing it without using a drop of poisonous spray.
Instead, they're helping farmers use nature's way to hold pests in check. David Baron of member station WBUR recently traveled to Benin and prepared our report.

(Footfalls, a machete digging)

BARON: Emil Nuessu, a farmer in the tiny West African nation of Benin, uses a machete to cut into the hard-baked soil. It's the dry season and the small farms of cotton and corn and oil palms are brown. But there is food hidden underground. Nuessu digs up chunks of dirt around a spindly plant about 5 feet tall topped by fans of greenish brown leaves. This is cassava, a staple crop for more than 200 million Africans. Nuessu is harvesting the plant's roots.

(Hubert Creassu speaks as digging continues.)

BARON: Nuessu's cousin, Hubert Creassu, explains his family eats cassava every day. The root, which looks like an elongated potato, can be boiled or grilled. It can be processed into flour and made into cakes. In the United States, cassava is known primarily as the source of tapioca. What makes cassava especially important is its reliability. During the dry season and during years of terrible drought, the plant can survive, storing energy, calories, in its roots. Cassava is often the last buffer against famine, but 20 years ago this buffer began to vanish.

(Creassu speaks)

BARON: Creassu shows a cassava leaf that's malformed, kind of bunched up: evidence of mealy bug damage. Creassu says mealy bugs in large numbers can destroy his crop. The mealy bug is one of 2 devastating cassava pests that arrived in Africa in the early 1970s and quickly spread across the continent, wiping out cassava fields across an area larger than the United States. Around 1980 a team of international scientists began assembling in Africa to address the mealy bug emergency. Swiss entomologist Hans Herren headed the effort.

HERREN: We needed really to have, like a Marshall Plan to deal with this, because the cassava's dying out.

BARON: The story of how Herren and his team controlled the mealy bug has gained almost legendary status in African agriculture. When the mealy bug first appeared in Africa some farmers tried insecticides. But the chemicals didn't work very well, and few farmers in Africa could afford them anyway. Herren had a different idea. If he could find the natural habitat of the mealy bug, he could probably find a natural enemy to keep it in check. Cassava was brought to Africa 4 centuries ago from South America, so Herren figured the mealy bug, which was adapted to eating cassava, must also have come from somewhere in the Americas.

HERREN: Anywhere between Southern California and Northern Argentina. This was the range, so we had a very hard time even to pinpoint where are we looking for this mealy bug.

BARON: After an exhaustive, year-long search, Herren and his team found the mealy bug living in Paraguay, where no one was aware of its existence.

HERREN: It's amazing, that people who have worked on cassava in Paraguay for years, they've never seen this thing, because it was, there were very few and nobody found this to be any problem.

BARON: It appeared Herren's intuition was correct. The mealy bug wasn't a problem in the Americas, so it must have its own natural enemies, its own pests, that keep it under control. Herren's team found a tiny wasp, no bigger than the tip of a pencil, that lays its eggs in the mealy bugs, killing them. After conducting field tests to make sure the wasp wouldn't cause any problems if introduced to Africa, Herren decided to rear thousands upon thousands of the insects in a laboratory, and then to shoot them out of the back of an airplane crisscrossing Africa, spreading the wasp from Senegal to Mozambique.

HERREN: A lot of people thought I was a bit out of my mind to do this: Basically it won't work.

BARON: But it did work, remarkably well.

HERREN: It established itself, and brought the mealy bug under control in let's say 95% of the cases.

BARON: It's estimated that within 20 years, for every dollar spent controlling the mealy bug, farmers will have saved $150 in crop losses. The project may end up saving the world billions of dollars in food aid. But controlling the mealy bug was only half the battle; the second devastating cassava pest, a tiny mite, continued to spread. In fact, with the mealy bug under control, the mite problem grew worse. American biologist Steve Yaninek now wants to do to the mite what Hans Herren did to the mealy bug.

YANINEK: See those mites there?

BARON: Yaninek stands in a field of cassava at the International Institute of Tropical Agriculture, just outside the city of Cotonou in Benin. He is peering through a magnifying glass at tiny green 8-legged animals on the underside of a leaf. The plants look sickly; their green leaves are covered with yellow spots.

YANINEK: See the spots where the green chlorophyll has actually been sucked out of the plant by the mites.

BARON: Yaninek and his colleagues, who also worked on the mealy bug effort, believe they can find a similar non-chemical solution to the green mite. Retracing the same steps over the course of a decade, the scientists have found a Brazilian bug they believe fits the bill. It's another mite that eats the cassava green mite. Yaninek has been testing this predatory mite on some of the plants in his field.

YANINEK: Overall, you can see that the foliage is much more lush. And all the plants have nice, big, healthy shoot tips. That's because of the predators that are in there.

BARON: Yaninek says the predatory mite has been tested successfully in Ghana, Sierra Leone, Cameroon, Uganda, Burundi, and Zambia. He hopes soon to have a large-scale distribution effort up and running to spread the bugs to farmers' fields across Africa's cassava growing belt. Peter Neuenschwander, who heads the agricultural research station where Yaninek works, says the threat to Africa's cassava crop may largely be over in a few years. And the feat will have been accomplished using methods appropriate for Africa, a continent with little infrastructure.

NEUENSCHWANDER: You don't need foreign currency, foreign exchange, to import things. You do not need machinery, you do not need water and so on. This offers sustainable solutions.

BARON: International agricultural experts are well aware of the cassava pest control effort in Africa and widely praise it. But few farmers or biologists in the developed world are familiar with the project. Cornell University entomologist Edward Glass hopes to see that change.

GLASS: I think it's a spectacular success. This method of plant protection ought to be taught and practiced to a wider extent.

BARON: Glass says biological control isn't appropriate for every pest, but the cassava story shows sometimes the best solution includes leaving pesticides on the shelf. In Africa, he points out, biological control saved millions of people from potential famine, while saving money and the environment as well. For Living on Earth, I'm David Baron reporting.

Back to top

(Music up and under)

CURWOOD: And for this week, that's Living on Earth. You can get a transcript or a tape of this program by sending a check for $10 to Living on Earth, Box 639, Cambridge, Massachusetts 02238.

CURWOOD: Our segment on biophilia was produced by Peter Thomson. Our staff also includes Deborah Stavro, George Homsy, Kim Motylewski, Constantine Von Hoffman, Jan Nunley, and Julia Madeson. We had help from Liz Lempert, Bob Emro, David Dunlap, and Susan Shepherd. Our engineers in the WBUR studios are Frank DeAngelis and Mark Navin. Special thanks to Jane Pipik and Larry Bouthillier. Our theme music was composed by Michael Aharon.

Living on Earth is a project of the World Media Foundation, and recorded at WBUR, Boston. I'm Steve Curwood, executive producer.

ANNOUNCER: Major contributors to Living on Earth include all-natural Stonyfield Farm Yogurt - whether supporting worthwhile causes or producing healthy foods, Stonyfield's goal is to make you feel good inside; the Great Lakes Protection Fund; the National Science Foundation for coverage of science in the environment, and the W. Alton Jones Foundation.

NPR ANNOUNCER: This is NPR, National Public Radio.


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