The Diversity of Life
is a 1992 book on the future of biodiversity by entomologist Edward O. Wilson. Widely regarded as the founder of the field of sociobiology, Wilson deftly combines data and rigorous scientific methods with different narratives about how biological life has evolved over time to argue that earth is hurtling towards the sixth mass extinction since organic life began. Wilson gravely warns that we have almost no idea what it will take to reverse the almost entirely human-caused sixth extinction. Moreover, he challenges the assumption that mass extinction will barely affect the relatively sophisticated human species. Not taking for granted his own theoretical fallibility, he proposes several strategies that might limit our impact on the environment to sub-critical levels.
Wilson, an entomologist whose deepest research has been on the behavior and reproduction of ant species, thinks of biodiversity and ecology in a different way than they are generally represented in popular science. In his analysis of how ecologies change, he focuses on no single species; rather, he strives to equally account for all species, regardless of location, function, or ecological niche. He contends that all living things are essential to the ecosystems in which they live and, therefore, should not be left out of any evaluation of biodiversity. While global warming might be synonymous with a polar bear on an ice floe in the popular imagination, to Wilson, the phrase represents a much more complex and systemic crisis that imperils millions of species.
Wilson thinks of extinction as a process that can happen on a multitude of scales and timelines, from the individual and momentary to the global and permanent. For example, one can think of the felling of a single tree as a tiny extinction and the annihilation of the dinosaur species as a large one. In the five largest extinctions in earth’s history, over 90 percent of the species alive at the time faded out. Wilson asserts that nature is a resilient force, and can quickly rebound from virtually any extinction. Yet, to recover from a large extinction takes tens of millions of years. Any human-caused extinction would take longer than the duration of the human species for the earth to repair itself.
Next, Wilson runs through several popular beliefs about evolution in contemporary life, analyzing their connections (or lack thereof) to biological theory. He explains that biodiversity cannot be understood without background knowledge in ecology, evolutionary theory, taxonomy, and classification. However, he acknowledges that none of these branches of knowledge is complete enough to fully understand life. He suggests that the best course of action given our uncertainty is to stick with the theories that have the greatest consensus among scientists. For example, he criticizes the accepted definition of “species” as a population in which individual organisms can interbreed under certain environmental conditions, but concedes that it is the best definition we have so far.
Wilson ends his book with notes on the impact humans make on biodiversity. He laments that the human species has destroyed many more species than it has nurtured. In virtually every ecological study of the effect of human flourishing on biodiversity, groups of organisms, especially flightless birds and large mammals, have suffered. These accounts range across North and South America, the Pacific, Africa, Asia, and Europe. He argues that the worst contributor to extinction in the current moment is habitat destruction, ranking as second the placement of foreign species into environments where they have not naturally developed an ecological niche. The silver lining to Wilson’s grave diagnosis is that since these two key factors account for the majority of extinctions, the formula for reversing extinction is already somewhat implicit in the problem. The Diversity of Life
exhorts its audience to shape public life in ways that minimize habitat destruction and to put pressure on elected officials to stall the sixth extinction before it is in full force.