Harmony and Conflict in the Living World - Alexander F. Skutch [75]
As a guiding principle for conservation, the following alternatives are worth considering. We should endeavor to promote: (1) maximum diversity, or number of species; (2) the maximum sustainable number of individual organisms; (3) those elements of the natural world that contribute most to human prosperity and happiness or are the least threat to these ends. Let us examine them in this order.
"Biodiversity," a neologism, has become the rallying cry of conservationists. That we could not survive without biodiversity, and a great deal of it, is a truth too obvious to naturalists to need elaboration. We need plants to produce food; insects, birds, and other creatures to pollinate their flowers; fungi and microorganisms to decompose dead tissues and return their fertilizing components to the soil; and much else. Recent explorations of the canopy of tropical forests have revealed that the number of extant species is much greater than we had supposed only a few decades ago and may run into millions.
Biodiversity has certainly become excessive, and is responsible for a major part of the sufferings of animals, including humans. In addition to all the predators that strike down living victims and too often begin to tear them apart before they die, an immense diver-
Page 153
sity of parasites torture, debilitate, and kill their hosts. Since most multicellular animals appear to be infected by several kinds of parasites, internal and external, many of which are restricted to a single species or closely related group, it is probable that parasites far exceed, in number of species and individuals, all other Metazoa, or multicellular animals. Moreover, they can weaken and kill plants or ravage whole forests. Undoubtedly, a great reduction of biodiversity, probably 50 percent or more, would make life much more pleasant not only for humans but for many other creatures.
Although we hear much about biodiversity, I am not aware of any widely accepted statement of its desirable limits. Should we promote the absolute maximum, which would include all parasites, pathogens, and predators, or should we be more discriminating? I doubt that any advocate of biodiversity would oppose the extermination of organisms responsible for human diseases, or of the blood-sucking insects that spread diseases and can make life miserable for many kinds of mammals. In regard to larger predators, the situation is confused. Many friends of animals would welcome the great reduction, if not extinction, of venomous and nest-robbing snakes, voracious alligators, the fiercer raptors, or the most dangerous sharks. If conservationists could agree on the desirable limits of biodiversity, cooperation and efficiency might increase.
Instead of promoting biodiversity absolutely or within certain well-defined limits, we might choose the alternative of making our goal the maximum number of individuals, of all kinds or of certain specified kinds, within the capacity of Earth to support them indefinitely in a flourishing state. The contrast between the first and second alternatives presents an interesting analogy to that between two opposing principles of human government. Totalitarians hold that individuals exist for the wealth, power, and glory of the state, which certain philosophers, such as Hegel, have viewed as having a collective spirit or soul, above that of its inhabitants, and which can demand their sacrifice for the exaltation of the whole. Liberal democrats believe that the state, devoid of a collective spirit, exists for the welfare of individuals, who alone enjoy and suffer.
Page 154
Similarly, advocates of unlimited biodiversity might view the global community of animals and plants, or perhaps the planet itself, with all its living cargo, as a superorganism, Gaia, which thrives most