We’re Hard-Wired to Crave Nature

Too little green in your life? You’re not alone. Science reveals why we need to spend time in nature.

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Stephen Kellert, a professor at Yale University’s School of Environmental Studies, had been asked by a retirement community to study whether the ponds, waterfalls, trees, gardens, and other elements of “biophilic” design throughout the 52-acre facility were beneficial to the elderly residents, perhaps improving their cognitive function, stress levels, or other physiological measures, and whether additional biophilic elements should be introduced.

You would think conducting a study like this would be fairly unremarkable, except for one thing. More than 30 years after Harvard biologist E.O. Wilson popularized the term biophilia in a 1984 book, it remains ill-defined, controversial, and short of rigorous empirical support—yet practical applications of it have spread like kudzu. Researchers such as Kellert, a leading exponent of biophilia, are left to run after the schools, corporate headquarters, health-care facilities, architects, and designers who claim biophilia as an established fact, calling, wait, wait for research to catch up with what you’re doing!

Wilson defined biophilia as an innate, genetically based affinity for the living world, manifested in an “urge to affiliate with other forms of life” such as grasslands, trees, and animals (not explicitly other humans). “Humans have a deep and enduring urge to connect with living diversity,” argues Kellert. Doing so brings numerous psychological and physiological benefits, allowing us to, in Kellert’s words, “prosper physically, emotionally, and intellectually.” Wilson claimed that this affinity for the living world is “quite likely resident in the genes themselves,” driving us to embrace the living world, particularly savannahs like those in which our ancestors evolved in Africa, because said genes provided a survival advantage to our ancestors. The genetic claim, in particular, has been controversial from the start, and evidence for it is still meager to nonexistent. Why, many have asked, if humans innately love nature so much, have we driven countless species into extinction, ravaged landscapes for short-term gain, and (voting with our feet) chosen cities over countryside?

Biophilia’s claim that “affiliating” with living (not rocks or water) nature is good for us launched scores of studies. Researchers reported stress reduction, improved attention, “mental restoration,” better health, increased longevity. In a frequently cited 1984 study, patients recovering from gallbladder surgery were randomly assigned to a room with a view of either a brick wall or a savannah-like environment dotted with trees.

“Those with a view of the parklike setting recovered faster and needed fewer painkillers,” Kellert said.

But is this a fair test? Brick walls aren’t much fun to look at, and can make a room seem claustrophobic. Perhaps it would have been more telling to compare the parklike view with that of something not alive or natural but still pleasant to look at—maybe a sculpture garden, majestic bridge, or other manmade structure.

Other studies have failed to zero in on the cause of whatever benefit they claimed. Perhaps being in nature promotes physical activity, good for both mental and physical health. Perhaps cleaner air is what causes the benefits. In both cases it’s not nature per se that promotes well-being, as biophiliacs contend, but something else entirely. Nor do the studies clearly isolate what they’re studying: Perhaps some of the benefits from “nature” have nothing to do with our supposed affinity for the living world, but with simple peace and quiet or getting away from the daily grind, as in studies finding that hauling participants into the wilderness improves their feelings of well-being. As a 2011 critique of the biophilia hypothesis pointed out, such “empirical findings can often be accounted for by alternative hypotheses.”

When I asked Kellert about that, he acknowledged that “the proof is not good. In many of the studies, the methodology has been challenging. We need a lot more research.” As for whether a sculpture garden or other manmade but beautiful setting might be similarly beneficial to mind and body, he said, “We just don’t have the data.”

In part, that’s because few scientists have taken biophilia seriously enough to study it. Virtually no biophilia studies have appeared in top scientific journals over the last 30 years. Those that have reported evidence for biophilia are rarely replicated by other scientists, a necessary step toward confirming any finding. And it is impossible to know how many studies disproving biophilia are never published because both researchers and journals prefer “positive” results, a well-documented problem in science.

Perhaps some of the benefits from “nature” have less to do with our supposed affinity for the living world than with simple peace and quiet or getting away from the daily grind.

As for the claim that we’re genetically driven to “affiliate” with nature, children should be the ideal population in which to test that, since they have had less time to learn to prefer manmade environments. Yet a 2014 study found that most kids who had access to nature showed no preference for biodiverse habitats, instead spending most of their outdoor time in their yard, on streets, or on athletic fields. Basically, the kids prefer places where they can play, not where they can immerse themselves in nature, something the researcher called a “lack of biophilic behavior.” I leave it to you to decide if your children seem to have a “natural” affinity for grass and flowers . . . or for iPads and other screens or simply other kids.

Peter Kahn, a professor of psychology in the School of Environmental and Forest Sciences at the University of Washington, belongs to the younger generation of biophilia researchers. He believes studies will continue to find that nature affects aspects of (some) people’s mental and physical functioning, but says such findings fall short of proving we’re uniquely wired to seek out and benefit  from the living world—more than, say, to seek out and thrive from being with other people. “Biophilia is not a scientific hypothesis, not in the stringent sense of being predictive, testable, and open to disconfirming evidence,” he argues. He now thinks biophilia “is best understood not in itself as a testable hypothesis” but as a “broad construct.”

Which brings us to Kellert and the retirement community. The lack of a scientific foundation for biophilia has not impeded architects and others from claiming it as fact, “bringing elements of nature into the built environment,” Kellert said, “including materials like wool and forms that mimic natural ones, like columns shaped like trees.” Google is testing biophilic design at its headquarters, introducing more plants, aquariums, views, and nature-mimicking geometries, he said, “to see how it affects retention and employee performance.”

Biophilia, particularly the claim that DNA has wired our brain to seek out and thrive in nature, remains very much a hypothesis. It’s also a fascinating case study of how a claim in cognitive psychology can take hold despite a lack of solid evidence. As I was writing this, the Presidential Commission for the Study of Bioethical Issues warned that when it comes to claims about the brain “hyperbole and misinformation permeate the conversation.” That exaggeration, it said, “can lead to undue excitement and attention, commonly referred to as ‘hype.’”

If you find a walk in nature restorative, as most of us do, that makes sense for a host of reasons, but can you claim you’re genetically disposed to do so and that your brain has been radically transformed?

Probably not.

Do you need to?

Probably not.

Have a nice walk.