The Diversity of Life
Edward O. Wilson, the Harvard scientist who is one of the world’s foremost authorities on the lives of ants and on the problems of ecology, begins his book on a dark night in the middle of the Brazilian rain forest:
The forest at night is an experience in sensory deprivation most of the time, black and silent as the midnight zone of a cave. Life is out there in expected abundance. The jungle teems, but in a manner mostly beyond the reach of the human senses. Ninety-nine percent of the animals find their way by chemical trails laid over the surface, puffs of odor released into the air or water, and scents diffused out of little hidden glands and into the air downwind. Animals are masters of this chemical channel, where we are idiots. But we are geniuses of the audiovisual channel, equaled in this modality only by a few odd groups (whales, monkeys, birds). So we wait for the dawn, while they wait for the fall of darkness; and because sight and sound are the evolutionary prerequisites of intelligence, we alone have come to reflect on such matters as Amazon nights and sensory modalities.
But is this as it should be? Wilson asks. Only one species is able to reflect on nature, but is it right that this unique species should commandeer the earth’s resources to the detriment of millions of others? There is a moral dilemma here, one that is felt acutely by a biologist whose passion is the diversity of life on earth.
What is the biodiversity of which Professor Wilson writes with such conviction and authority? What is the scope of it? How did it originate? Where is it found? How are humans diminishing it? And why should it matter that humans are diminishing it? Professor Wilson offers answers to all these questions in engaging and nontechnical prose. His account, accompanied by a scattering of line drawings, is carefully organized, systematic, and instructive, and could serve as a college text. But it is much more than a text in its prodigious erudition and its original and fascinating insights into the Lilliputian world of insects, mites, and microbes.
Biodiversity, in the simplest terms, is the sum total of life, comprehending all species of organisms, large and small, terrestrial and aquatic. Notice that the units are species, mutually interbreeding populations which are reproductively isolated from other sets of interbreeding populations. Some scientists would expand the definition of biodiversity to include the genetic information contained in all organisms, on the grounds that the genetic makeup of every individual of a sexually reproducing population is unique. But, with few exceptions, the genes carried by individuals are not unique. Most genes are widely dispersed in populations. Individuals serve only as their transitory bearers. Genetic continuity is maintained in populations, and the distinctions between the populations of a species tend to blur over time as individuals disperse and habitats shift in space. Hence it is most reasonable, as well as …