16.1–16.4: Biodiversity—of genes, species, and ecosystems—is valuable in many ways

Endangered Nilgiri tahr (Nilgiritragus hylocrius) visit a grassy alpine plateau in India.

In the Pacific Northwest of the United States, a medium-size tree grows. This conifer, the Pacific yew tree (Taxus brevifolia), isn’t the biggest tree in the forest, nor is it the most common. But within the bark of the Pacific yew there is a chemical that is pretty remarkable. It’s called taxol, and it acts as an anti-cancer agent, interfering with the division of cells that come into contact with it (FIGURE 16-1). Although we don’t fully understand the role taxol plays for the Pacific yew—it may reduce the rate at which other organisms feed on the plant—in humans, taxol is effective in the treatment of ovarian cancer, breast cancer, and lung cancer (generating more than $1 billion a year in pharmaceutical sales).

Figure 16.1: Taxol is cancer medicine derived from a tree.

Consider also the following:

• The chemicals vinblastine and vincristine, isolated from the Madagascar periwinkle (Catharanthus roseus), are so effective in treating leukemia and Hodgkin’s lymphoma that both diseases, formerly incurable, are now curable in the vast majority of people.
• The chemical ancrod, found only in the Malayan pit viper snake (Agkistrodon rhodostoma), dissolves blood clots and is effective in treating some heart attack and stroke patients.
• Epibatidine, a poisonous compound in the saliva of a small frog (Epipedobates tricolor) that lives in Ecuador, is 200 times more effective than morphine in relieving pain and is non-addictive.

These are just a few examples—there are many, many more—illustrating that medically important compounds often come from other organisms living in a wide variety of locations around the world. Toxin production commonly evolves in these organisms as a method of protecting them from other organisms. Co-opting the chemicals for human use reveals that one important value of the diverse plants and animals around the world is as a sort of universal medicine cabinet.

Plants and animals aren’t the only species with great value to humans. Microbes, too, have great utility. In the next section, for example, we see that hydrocarbon-consuming bacteria can play a significant role in cleaning up oil spills (FIGURE 16-2).

Figure 16.2: Can bacteria help clean up an oil spill?

Medicinal compounds derived from plants and animals, as well as the activities of oil-removing microbes, are just a few examples of how humans use the chemicals and metabolic processes that occur in other organisms. The plants, animals, and microbes in which these compounds and processes occur are examples of biodiversity, which is defined as the variety of genes, species, and ecosystems on earth. And, as we’ve seen, there is tremendous value that can come from earth’s biodiversity, and it often comes from unexpected places. For these reasons, the loss of biodiversity—including genes, species, and ecosystems—can be hugely detrimental to humans.

But viewing the value of biodiversity only in the context of our abilities to extract medicines or to better process the messes we make is to take much too narrow a perspective. Taking a philosophical perspective, the United Nations has asserted that biodiversity has an intrinsic value—that is, an inherent value independent of its value to humans—stating that “every form of life is unique, warranting respect regardless of its worth to man.”

And, in describing the extrinsic or utilitarian value of biodiversity, scientists and economists use the concept of ecosystem services to highlight the benefits to humans that come from biodiversity and natural ecosystems. In a 2005 United Nations study that involved more than 1,300 scientists, the researchers identified four distinct categories of ecosystem services (FIGURE 16-3).

Figure 16.3: Ecosystem services categorize the many different ways that biodiversity has value to humans.

• Provisioning services. These include the many useful products that humans obtain from nature, including food, spices, minerals, and pharmaceutical and industrial products.
• Cultural services. Much of the value that humans gain from biodiversity isn’t easily assigned a dollar value—but that value can be extremely important just the same. We think of a field of flowers or a deer in the woods as beautiful to look at and pleasant to experience, for example. Or we make use of images of animals and plants to convey meaningful abstract ideas: the dove as a symbol of peace; the oak as a symbol of strength; the butterfly as a symbol of transformation; and the owl as a symbol of wisdom. Beyond the aesthetic, symbolic, and spiritual values of biodiversity, cultural services also include recreational experiences, as well as scientific and other educational value.
• Regulating services. Ecosystems provide numerous services relating to the regulation of our environment. These include climate regulation through carbon storage in plants; pollination; waste decomposition and detoxification; protection from natural disasters; and pest and disease control.
• Habitat services. Significant value from biodiversity and natural ecosystems also flows to humans in the form of soil formation, photosynthesis, and nutrient cycling.

When we recognize that people can view the same organism or gene or ecosystem and value it in different ways, we are on our way to making wiser conservation decisions. This knowledge, for example, can help us anticipate potential conflict when it comes time to invest limited conservation resources in conserving biodiversity and can help us seek out methods for balancing conflicting desires. We explore some strategies for making these difficult decisions later in this chapter.