Why should we care about nature? Should we care about it for its own sake — or for our sake, because it happens to make us happy or healthy? These might not seem like the brightest questions. Few people need convincing that the destruction of rain forests, the mass extinction of species and the melting of the ice sheets in Greenland would all be very bad things. Do we really need to list the reasons?
We do. After all, in many regards our species has already kissed nature goodbye, and we are better off for it. Technology has come to be more diverse than the biosphere. In 1867, Karl Marx observed that there were 500 types of hammer made in Birmingham, England. In 1988, Donald Norman, a cognitive scientist at the University of California, San Diego, suggested that the average American encounters 20,000 different kinds of artifacts in everyday life, which would be more than the number of animals and plants that we can distinguish. And right now, there are about 1.5 million identified species on Earth — impressive, but nothing compared to the more than 7 million United States patents.
This is mostly good news. No sane person would give up antibi¬otics and anesthesia, farming and the written word. Our constructed environments shield us from heat and cold and protect us from predators. We have access to food and drink and drugs that have been devised to stimulate our nervous systems in magnificent ways. We sleep in soft beds and have immediate access to virtual experiences from pornography to classical symphonies. If a family of hunter-gatherers were dropped into this life, they would think of it as a literal heaven.
Or maybe not. There is a considerable mismatch between the world in which our minds evolved and our current existence. Our species has spent almost all of its existence on the African savanna. While there is debate over the details, we know for sure that our minds were not adapted to cope with a world of billions of people. The life of a modern city dweller, surrounded by strangers, is an evolutionary novelty. Thousands of years ago, there was no television or Internet, no McDonald’s, birth-control pills, Viagra, plastic surgery, alarm clocks, artificial lighting or paternity tests. Instead, there was plenty of nature. We lived surrounded by trees and water and animals and sky.
This history has left its mark on our minds. Children are irrepressible taxonomizers, placing the world of distinct individuals into categories based on their appearance, their patterns of movement and their presumed deeper natures, and some psychologists have argued that the hard-wired capacity to organize and structure the world is specially adapted to nature: we are natural-born zoologists and botanists. We may also have evolved to get pleasure from certain aspects of the natural world. About 25 years ago, the Harvard biologist E. O. Wilson popularized the “biophilia” hypothesis: the idea that our evolutionary history has blessed us with an innate affinity for living things. We thrive in the presence of nature and suffer in its absence.
Our hunger for the natural is everywhere. It is reflected in art: the philosopher Denis Dutton, in his book “The Art Instinct,” suggests that popular taste in landscape painting has been shaped by preferences that evolved for the African savanna. The appeal of the natural is also reflected in where we most want to live. People like to be close to oceans, mountains and trees. Even in the most urban environments, it is reflected in real estate prices: if you want a view of the trees of Central Park, it’ll cost you. Office buildings have atriums and plants; we give flowers to the sick and the beloved and return home to watch Animal Planet and the Discovery Channel. We keep pets, which are a weird combination of constructed things (cats and dogs were bred for human companionship), surrogate people and conduits to the natural world. And many of us seek to escape our manufactured environments whenever we can — to hike, camp, canoe or hunt.
Wilson emphasizes the spiritual and moral benefits of an attachment to nature, warning that we “descend farther from heaven’s air if we forget how much the natural world means to us.” But there are more tangible benefits as well. Many studies show that even a limited dose of nature, like a chance to look at the outside world through a window, is good for your health. Hospitalized patients heal more quickly; prisoners get sick less often. Being in the wild re¬duces stress; spending time with a pet enhances the lives of everyone from autistic children to Alzheimer’s patients. The author Richard Louv argues that modern children suffer from “nature-deficit disorder” because they have been shut out from the physical and psychic benefits of unstructured physical contact with the natural world.
So the preservation of the natural world should be important to us. But how important? The psycholo¬gist Philip Tetlock has pointed out that many people talk about the environment as a “sacred value,” protected from utilitarian trade-offs — when the Exxon Valdez spilled nearly 11 million gallons of crude oil, 80 percent of the respondents in one poll said that we should pursue greater environmental protection “regardless of cost.” But he also points to the need to balance environmental concerns with social and political and personal priorities. (Few of these respondents would be willing to hand over their pensions for a more efficient cleanup of the Alaskan shoreline.) And even if we did value nature above everything else, we would still have to decide which aspects of nature we care about the most. You can see this in the debate over the creation of giant wind farms in the ocean or on hillsides. Proponents are enthusiastic about the cheap, green energy; critics worry about the loss of natural beauty and the yearly filleting of thousands of songbirds and ducks.
In the end, an indiscriminate biophilia makes little sense. Natural selection shaped the human brain to be drawn toward aspects of nature that enhance our survival and reproduction, like verdant landscapes and docile creatures. There is no payoff to getting the warm fuzzies in the presence of rats, snakes, mosquitoes, cockroaches, herpes simplex and the rabies virus. Some of the natural world is appealing, some of it is terrifying and some of it grosses us out. Modern people don’t want to be dropped naked into a swamp. We want to tour Yosemite with our water bottles and G.P.S. devices. The natural world is a source of happiness and fulfillment, but only when prescribed in the right doses.
You might think that technology could provide a simulacrum of nature with all the bad parts scrubbed out. But attempts to do so have turned out to be interesting failures. There is a fortune to be made, for instance, by building a robot that children would respond to as if it were an animal. There have been many attempts, but they don’t evoke anywhere near the same responses as puppies, kittens or even hamsters. They are toys, not companions. Or consider a recent study by the University of Washington psychologist Peter H. Kahn Jr. and his colleagues. They put 50-inch high-definition televisions in the windowless offices of faculty and staff members to provide a live view of a natural scene. People liked this, but in another study that measured heart-rate recovery from stress, the HDTVs were shown to be worthless, no better than staring at a blank wall. What did help with stress was giving people an actual plate-glass window looking out upon actual greenery.
All of this provides a different sort of argument for the preservation of nature. Put aside for the moment practical considerations like the need for clean air and water, and ignore as well spiritual worries about the sanctity of Mother Earth or religious claims that we are the stewards of creation. Look at it from the coldblooded standpoint of the enhancement of the happiness of our everyday lives. Real natural habitats provide significant sources of pleasure for modern humans. We intuitively grasp this, and this knowledge underlies the anxiety that we feel about nature’s loss. It might be that one day we will be able to replace the experience of nature with “Star Trek” holodecks and robotic animals. But until then, this basic fact about human pleasure is an excellent argument for keeping the real thing.