Book Review - "Sustaining Life: How Human Health Depends on Biodiversity" edited by Eric Chivian and Aaron Bernstein
“Sustaining Life: How Human Health Depends on Biodiversity”
Editors: Eric Chivian and Aaron Bernstein
Publisher: Oxford University Press
How can the layperson learn about the incredible importance of biodiversity to our ecosystems and our own human survival? Editors Eric Chivian and Aaron Bernstein have assembled an easily accessible collection of chapters that describe the historical understanding of biodiversity as well as its current relevance. The text is supplemented by a superb set of color photos, maps and diagrams to reinforce the messages. Topics range from basic descriptions of what biodiversity means to its application in medicine, agriculture and ecosystem services. As a good primer on the topic, “Sustaining Life” should be read and digested. One of the editors’ main goals is to raise awareness about how critical loss of species will eventually impact our own health and survival.
The major focus of the book is on this human impact and how we have profoundly altered the environment on this Spaceship Earth. Although one frequently reads articles about the loss of biodiversity, rarely are the consequences of such loss on our own well-being articulated as well as in this collection. In addition to creating awareness, the editors and authors provide clear steps to action to preserve what, ultimately, is needed to preserve ourselves.
The book opens with some historical description of how we have chosen to classify living organisms, including the creation of a binomial system of Latin names by the Swedish physician and botanist Carolus Linnaeus. The corn plant is Zea mays, we are Homo sapiens and our relative the western lowland gorilla (including its subspecies name) is Gorilla gorilla gorilla. These names are universally used and help avoid the confusion across languages and cultures where the same plant may have many different common names, or one common name may refer to several quite different plants. Names and descriptions are essential for the study of biodiversity, and there have been over 1.5 million species of living organisms identified. Estimates are that we only have given names to perhaps 10 to 15 percent of all species that are present on the planet, and new ones are being discovered every year … yet we are also losing species at a rate of 100 to 1,000 times the rate before humans emerged. The case for preservation suggests that biodiversity “provides a kind of insurance policy for ecosystems, buffering them against such stresses as temperature changes, diseases, and pests that can result in species loss and ecosystem disruption. This is known as ecosystem resilience or ecosystem reliability” (p. 25). We need a stable, natural ecosystem for our own survival.
What are we doing to cause loss of species? In the terrestrial ecosystem, deforestation, spread of cities into wildlife and plant habitat, hunting and even agriculture may eliminate the niche where certain species live and reproduce. In the oceans, it appears that overfishing, intensive exploitation through indiscriminate trawling and lack of effective global accords contribute to loss. In freshwater habitats the introduction of exotic species, draining of wetlands and dredging of rivers, and pollution through such activities as coal mining all contribute to species loss. There are dead zones near the outlets of major river systems where excess nutrients and pesticides contribute to loss of life. A newly recognized threat to biodiversity is the discarding of antibiotics and pharmaceuticals that enter the environment and disrupt reproduction or cause the buildup of resistant strains of pathogens that cannot be controlled by known medicines.
Little understood by the general population and poorly rewarded in the marketplace are the ecosystem services provided by natural areas and farmlands. Farms and forests produce food, timber and fiber to meet our needs. Yet we take for granted the oxygen produced by green plants, the capture and storage of rain by wetlands and soils with high organic matter content and ways that trees change the local microclimate to our advantage. One service we do appreciate is the range of medicines that originally were derived from plants. Since organisms in the wild have adapted to protect from pests of all types, we can use this information to find compounds that can help in human health. Although we often synthesize these in the factory later, many of our modern medicines were first discovered in nature. Loss of habitats to development, and to farming, leads to loss of biodiversity in the microorganisms that may be important in medicine in the future. A chapter on biomedical research and another on which groups of organisms are most threatened provide examples of why we should not lose this critical biological resource. Another chapter gives insight on the complexity of function and internal controls of disease in natural habitats, and how the loss of these critical systems through human encroachment and development pushes things out of balance and opens niches where larger infectious problems can emerge. We are familiar with lyme disease and West Nile Virus in Nebraska that are, in part, a function of land-use changes and destruction of habitat and natural controls. The information on medical dependence is provided in special detail, since the book’s editors are both physicians.
Of vital interest to those in agricultural states, where reliance on food production drives the economy and has helped us to keep our unemployment down, are the changes in this sector that contribute to habitat loss and suppression of many wild species that help keep the system in balance. We once had a highly diverse food system, as people included hundreds of plant species and many sources of animal protein in their diets. Specialization and focus on a few highly productive food sources has narrowed this diet to about 20 different species on which most of humankind depends. Production has surely been enhanced by application of chemical fertilizers and pesticides and by irrigation where rainfall is not sufficient. But homogenizing the production environment through wide use of these inputs has suppressed the potentials for biological controls of plant pathogens (causing diseases), insects and weeds. Bird populations and diversity of species have declined, and there is a serious reduction in the vitality and survival of bees and other pollinators that are essential to production of many crops. Genetic erosion occurs in farming areas when new varieties are widely planted, perhaps increasing yields but reducing the resilience of systems. Aquatic systems have mainly suffered from overfishing, but in some areas the impacts of agricultural pesticide and fertilizer runoff has created essentially dead zones where no fish or other marine life can be found.
There is a large debate today about the potentials and drawbacks of transgenic (GM) crops, those derived by clever transfer of genetic information from one species to another. Plants have been genetically selected since the first women emerged from caves and began to choose those plants with larger seeds, those that did not scatter seeds but held them tightly until harvest and those with better taste and nutritional value. Plant breeders have made tremendous contributions to global food production through the Green Revolution by refining this selection process. The so-called GM technologies take this genetic process to another level, moving genes from one species to another, often using a bacterium as the transfer agent. Although the new varieties derived by this process have proven useful for resistance to some insects and herbicides, they have not raised the yield potential of crops. It is an expensive technology, and one that many feel has not yet been adequately tested for its impact on human health. There is a question about the opportunity cost of pursuing this narrow strategy of plant improvement and concern about the concentration of ownership of the technology by one or two companies. Organic farming is one alternative strategy that avoids the use of GM crops as well as applied synthetic chemicals, and proponents think that this is the way of the future. In any case, maintaining biodiversity in the food production landscape appears to be desirable for long-term sustainability of our food supply.
With what we know about the positive side of maintaining biodiversity, and the negative impacts of its loss, what can we do as consumers and citizens? The last chapter in “Sustaining Life” provides some obvious guidelines: consume less, follow the strategy of reduce/reuse/recycle, minimize our ecological footprints and eat food produced closer to home. There is a litany of suggestions on reducing energy use in transportation and housing and a number of specific ideas about how we can preserve biodiversity in our own gardens, nearby parks and other open spaces in the public domain. These steps all reduce our consumption of energy and materials and thus our impact on natural habitat and resource supplies. Ultimately, this can help preserve natural biodiversity.
Would you like to have this book on your coffee table in the den? Although it is nicely illustrated and interesting to flip through, it is more than a typical large-format entertainment source. “Sustaining Life” presents serious science in a format and language that is easily accessible to a wide audience. The messages are clear about the importance of biodiversity, and a concerned reader will walk away from the book with increased awareness of the fragility of our global ecosystem as well as a number of concrete ideas on what each of us can do to change the situation. It is highly recommended as a science-based but popular introduction to the complex topic of biodiversity and why we should all care about its loss.
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