The Future of Life

At the outset of Chapter 4, Wilson describes his encounter with Emi, a female Sumatran rhino. While the meeting was unremarkable on its face, Wilson says it was magical: “I had at last met my real-life unicorn” (79). Sumatran rhinos are special because of their rarity—as of 2001, there were only 300 left—and because their genus dates back 30 million years, one of the longest lineages of any mammal.

Over time, the rhinos’ population has shrunk, but this doesn’t mean that the species’ time on Earth is up, Wilson says. With effort, even species that are down to a single pair—like the Mauritian kestrel—can rebound. Such measures are unlikely to work for the Sumatran rhinos, however, because they perform poorly in captive breeding programs and are facing habitat destruction and poaching—driven by demand from Asia, where rhino horn figures prominently in Chinese traditional medicine, and the Middle East, where rhino horn is used in the handle for a Yemeni ceremonial dagger. Western nations have no moral high ground to stand on when critiquing such practices, Wilson notes: Western demand for shawls made from the wool of a Tibetan antelope and for abalone have driven down numbers of those species—in the case of the white abalone, almost to extinction.

The relationship between the presence of humans and the extinction of species is not new. In Australia, the arrival of European colonists was followed by the extinction of 16 of Australia’s 263 native mammals. Long before that, megafauna such as giant tortoises, sloths, and flightless birds had already disappeared—shortly after the arrival of aboriginal people, roughly 60,000 years ago—a process that was repeated in places like Madagascar and New Zealand. While Wilson acknowledges the evidence is circumstantial, it is also persuasive enough to call Homo sapiens “the serial killers of the biosphere” (94). This destructive pattern follows a “filter principle”: The further back in time the initial impact from human colonization, the lower the current extinction rate, because only the most resilient species are now left to endanger. This principle explains why Hawaii, more recently colonized by humans, has more endangered species.

In Chapter 3, Wilson also explains how extinction rates are calculated. The best way, Wilson says, is to first look at the relationship between the area of a habitat and the number of species it can support (as it shrinks, it will support fewer species); second, track the velocity with which species become more threatened, according to the World Conservation Union Red List—the preeminent endangered species list—categories, until they eventually reach extinction; and finally, assess how likely it is that a given species on the Red List will survive.

It is impossible to calculate how many species will go extinct in the future, as extinction depends on human choice. While humans have been responsible for biodiversity decline since the earliest days of Homo sapiens, Wilson says it’s possible, with increased understanding of the problem, that humans of the 21st century will act differently. 

Wilson attempts to establish a way to measure the economic value of biodiversity, asking how we can assess the worth of the species—such as the ivory-billed woodpecker, once found in the Southern United States and now extinct—that are disappearing. One measure, he says, is to put a dollar amount on the value of the ecosystem services—the “flow of materials, energy and information from the biosphere that support human existence” (106)—that natural environments provide to humanity. Economists and scientists estimated this value at $33 trillion in 1997, meaning that if humans were to replicate the services natural environments provide, global GNP would have to increase by around $33 trillion (although such a replacement, Wilson notes, is not actually possible). Examples of how difficult ecosystem services are to replicate include how the depletion of fish stocks is leading to dependence on aquaculture, or fish farming, which is environmentally destructive and resource-intensive, or how the protection of the watershed in the Catskill Mountains has provided clean water to New York City residents, at a cost much lower than a water filtration plant. 

Natural environments can provide these ecosystem services, Wilson writes, because they’re biodiverse: “the more species that live together, the more stable and productive the ecosystems they compose” (110). Studies suggest that biodiverse ecosystems are more productive because interactions between species can stimulate their growth, in a process called “overyielding.”

Wilson goes on to note that agriculture, in particular, benefits from biodiversity, as diverse species are potential donors of genetic material that can improve the roughly 100 species of plants that form the basis of the world’s food supply though genetic engineering. Genetic engineering has already produced pest-resistant plants, plants that are resistant to weed-killers, and golden rice, which contains beta-carotene but has also sparked widespread opposition. This opposition may be warranted, Wilson says, noting risks such as ethical concerns around the rapid modification of life, unknown effects on human health, and the potential for a genetic engineered plant to mix with wild relatives.

Medicine also benefits from biodiversity, as some pharmaceuticals are based on wild species; nine out of 10 leading prescription drugs originated with organisms. The potential for biodiversity to contribute to medicine is relatively untapped, Wilson notes, citing as an example the ascomycete fungi, which have yielded 85% of antibiotics in use but of which only two percent of all species have been studied. As Wilson goes on to note, such sources of knowledge and resources are disappearing almost as fast as scientists can discover them. The race to uncover the useful resources of an ecosystem is called bioprospecting, and it can be sustainable, if disturbance to the ecosystem is kept to a minimum. The same is true economically, Wilson says: In an environment like the tropical forests of Belize, bioprospecting yields more value than agriculture. Wilson closes the chapter by noting that some of the profits from bioprospecting can be directed to conservation, further aiding in the preservation of biodiversity.