As journalist and author Florence Williams found, nature deprivation is a global phenomenon. With more than half of the world’s population now living in cities, it’s an increasing trend many have likely experienced firsthand. As are prescriptions for antidepressants. Williams notes that one in four middle-aged American women takes or has taken antidepressants. Meanwhile, one in 14 children takes a drug for emotional or behavioral problems, reflecting about a fivefold increase since 1994. What’s going on — and can spending more time in nature help what ails us? 

In her book “The Nature Fix: Why Nature Makes Us Happier, Healthier, and More Creative,” Williams explores humans’ relationship with the natural world and the science behind nature’s positive effects on the brain. In writing the book, she visited nature neuroscience researchers on four continents, from forest bathing sites in Japan, to islands in Finland, to eucalyptus groves in California. In the below excerpt, hear what she learned from physical anthropologist Yoshifumi Miyazaki about the practice of Japanese forest bathing, which involves cultivating your senses to open them to the woods, as part of her visit to one of Japan’s 48 official “Forest Therapy” trails. Plus, don’t miss Bioneers’ conversation with Williams about the book, including the strongest and most surprising evidence she found about why humans need to get out in the natural world. 

Excerpted from The Nature Fix: Why Nature Makes Us Happier, Healthier, and More Creative by Florence Williams. Copyright © 2017 by Florence Williams. Used with permission of the publisher, W. W. Norton & Company, Inc. All rights reserved.

The circumscribed, urban life is of course not unique to Japan. I now reflected the nature-deprived trends myself. I spend too much time sitting inside. I maintain multiple social-media platforms that attenuate my ability to focus, think and self-reflect. Since moving (from Boulder, Colorado) to D.C., I’ve had crying jags in traffic jams, and at times I’ve been so tired I’ve had to pull over and nap on MacArthur Boulevard. When I do get out “in the woods,” I seem to be doing it all wrong, forgetting or unable to hear the birds or notice any dappled anything. Instead, I grumble and obsess over my fate, my relationships and my kids’ new schedules, which require military precision and Euclidean traffic calculations.

A couple of months after I moved, I told my new doctor I was feeling depressed. She did what general practitioners everywhere are doing and sent me off with a script for Zoloft. One in four middle-aged American women takes or has taken an antidepressant. One in fourteen children takes a drug for emotional or behavioral problems, reflecting about a fivefold increase since 1994. For me, as for a sizable percentage of others with mild depression, the meds didn’t seem to work, and I hated the common side effects, which include everything from headaches to insomnia to low libido.

Moving on, I tried to grasp the destress crowd’s favorite darling, meditation. The science is very convincing that it changes your brain in ways that make you smarter and kinder and generally less ruffled by life. The problem is, as with antidepressants, meditation doesn’t work for many of us. Only 30 percent of aspirants are “fully adherent” after a standard eight-week course, according to Joshua Smyth, a biobehavioral psychologist at Pennsylvania State University. It has a high threshold to enlightenment.

But pretty much any slouching screen fiend can spend time in a pocket of trees somewhere. If there was one man who can demonstrate how forest therapy works, it’s Yoshifumi Miyazaki. A physical anthropologist and vice director of the Center for Environment, Health and Field Sciences at Chiba University on the outskirts of Tokyo, he believes that because humans evolved in nature, it’s where we feel most comfortable, even if we don’t always know it.

In this, he is a proponent of a theory popularized by the widely revered Harvard entomologist E. O. Wilson: the biophilia hypothesis. It’s been more or less appropriated by environmental psychologists into what’s sometimes called the Stress-Reduction Theory or Psycho-Evolutionary Restoration Theory. Wilson didn’t actually coin the word “biophilia”; that honor goes to social psychologist Erich Fromm, who described it in 1973 as “the passionate love of life and of all that is alive; it is the wish to further growth, whether in a person, a plant, an idea or a social group.”

Wilson distills the idea more precisely as residing in the natural world, identifying “the innately emotional affiliation of human beings to other living organisms,” as an evolutionary adaptation aiding not only survival but broader human fulfillment. Although no specific genes have been found for biophilia, it’s well recognized—ironically, some from studies of biophobia or fear—that even today our brains respond powerfully and innately to natural stimuli. One powerful example: snake! Our visual cortex picks up snake patterns and movements more quickly than other kinds of patterns. It’s likely that snakes even drove the evolution of our highly sensitive depth perception, according to University of California anthropologist Lynne Isbell. She discovered special neurons in the brain’s pulvinar region, a visual system unique to humans, apes and monkeys. Primates who evolved in places seething with venomous snakes have better vision than primates who didn’t evolve in those places.

The biophilia hypothesis posits that peaceful or nurturing elements of nature helped us regain equanimity, cognitive clarity, empathy and hope. When love, laughter and music weren’t around, there was always a sunset.

But survival wasn’t only about avoiding harm. It was also about finding the best food, shelter and other resources. It makes sense that certain habitats would trigger a neural bath of happy hormones, and that our brains would acquire the easy ability to “learn” this in the same way we learn to fear snakes and spiders. Going beyond that, our ancestors also had to learn how to recover from stress, Pleistocene-style. After they were chased by a lion or dropped a precious tuber over a cliff, they had to get over it in order to be welcomed back to the tribe, without which there was little survival. The biophilia hypothesis posits that peaceful or nurturing elements of nature helped us regain equanimity, cognitive clarity, empathy and hope. When love, laughter and music weren’t around, there was always a sunset. The humans who were most attuned to the cues of nature were the ones who survived to pass on those traits. Biophilia explains why even today we build houses on the lake, why every child wants a teddy bear, and why Apple names itself after a fruit and its software after noble predators, surfing spots and national parks. The company is brilliant at instilling biophilic longing and affiliation at the very same time it lures us inside.

It should come as no surprise that crosstalk operates between the brain and nature, but we’re less aware of the ever-widening gulf between the world our nervous systems evolved in and the world they live in now. We celebrate our brains’ plasticity, but plasticity goes only so far. As Miyazaki explained it, “throughout our evolution, we’ve spent 99.9 percent of our time in nature. Our physiology is still adapted to it. During everyday life, a feeling of comfort can be achieved if our rhythms are synchronized with those of the environment.” Of course, he’s talking about the nice parts of nature found in the hillsides of Japan, not the pestilential scum ponds or barren terrains of the globe that also constitute nature. Stick an office worker there, and relaxation will likely not be happening. But Miyazaki points out that naturalistic outdoor environments in general remain some of the only places where we engage all five senses, and thus, by definition, are fully, physically alive. It is where our savanna-bred brains are, to borrow from John Muir, “home,” whether we consciously know it or not. By contrast, Muir wrote of time not in the wilderness: “I am degenerating into a machine for making money.” Make that a machine with clogging pipes.

Miyazaki points out that naturalistic outdoor environments in general remain some of the only places where we engage all five senses, and thus, by definition, are fully, physically alive.

To prove that our physiology responds to different habitats, Miyazaki’s taken hundreds of research subjects into the woods since 2004. He and his colleague Juyoung Lee, then also of Chiba University, found that leisurely forest walks, compared to urban walks, deliver a 12 percent decrease in cortisol levels. But that wasn’t all; they recorded a 7 percent decrease in sympathetic nerve activity, a 1.4 percent decrease in blood pressure, and a 6 percent decrease in heart rate. On psychology questionnaires, they also report better moods and lowered anxiety.

As Miyazaki concluded in a 2011 paper, “this shows that stressful states can be relieved by shinrin therapy.” And the Japanese eat it up, with nearly a quarter of the population partaking in some shinrin action. Hundreds of thousands of visitors walk the Forest Therapy trails each year.