第1章
Nature's Healing Touch: The Science Behind Our Need for the Outdoors
When Florence Williams moved from her mountain home in Colorado to Washington, D.C., she experienced a profound shift in her mental state. The absence of nature in her daily life led to depression, difficulty focusing, and a general sense of malaise that medication couldn't fix. This personal crisis launched her on a global investigation into how nature affects our brains and bodies. Her journey-which became the bestselling book "The Nature Fix"-has been praised by figures from Richard Louv to Michael Pollan as a groundbreaking exploration of biophilia, the innate human connection to nature. As climate change threatens our natural spaces and urbanization accelerates (with over 55% of humans now living in cities), Williams' research has never been more relevant. Her findings have influenced urban planning policies in Singapore, forest therapy programs in South Korea, and a growing movement of physicians prescribing "park prescriptions" to patients suffering from everything from ADHD to PTSD.
第2章
The Biophilia Effect: How Nature Rewires Our Stressed Brains
In Japan's Chichibu-Tama-Kai National Park, I joined a dozen participants for shinrin yoku, or "forest bathing"-a standard preventive medicine practice. Our guide Kunio instructed us to stand still and breathe methodically while focusing on our surroundings. Most participants were tired urban office workers, including Tokyo businessman Ito Tatsuya, whose shoulders visibly relaxed as we breathed in the pine-scented air.
This park hosts one of forty-eight official "Forest Therapy" trails in Japan, where the Forestry Agency has invested $4 million in research since 2003. Visitors' blood pressure is routinely measured before and after hikes, with my own dropping slightly and Ito's even more dramatically.
For overworked Japanese facing the world's third-highest suicide rate, forest bathing offers essential relief. But this nature-deficit affects people worldwide. The biophilia hypothesis, popularized by E.O. Wilson, suggests humans evolved to feel most comfortable in natural settings. Our brains respond powerfully to natural stimuli-both threats like snakes and restorative elements that helped our ancestors recover from stress.
Pioneering researcher Yoshifumi Miyazaki has documented how forest walks decrease cortisol levels by 12%, reduce sympathetic nerve activity, lower blood pressure, and improve mood. "Throughout our evolution, we've spent 99.9% of our time in nature," he explains. "Our physiology is still adapted to it."
Since 2004, Miyazaki has taken hundreds into the woods, documenting how forest walks deliver significant physiological benefits compared to urban walks. Nearly a quarter of Japan's population now participates in shinrin therapy, with hundreds of thousands visiting Forest Therapy trails yearly.
When I joined Miyazaki at Juniko state park as one of his research subjects, he measured my vital signs after forest-bathing, then compared them to readings taken in urban environments. These metrics reveal how environments trigger either our parasympathetic "rest and digest" system or our sympathetic "fight-or-flight" system. My fifteen-minute forest walk was deeply sensory-cicadas pulsing, light filtering through trees, the smell of damp earth. My systolic blood pressure dropped six points. Later, walking through downtown Hirosaki's concrete, traffic and fumes, it rose six points.
Qing Li, an immunologist collaborating with Miyazaki, discovered that forest bathing increases natural killer (NK) immune cells by 40% for up to seven days. He attributes this to phytoncides-aromatic compounds emitted by trees. Even hotel rooms diffused with cypress oil showed a 20% increase in NK cells. "It's like a miracle drug," Li told me.
第3章
Healing Waters: How Rivers and Lakes Restore Traumatized Minds
The Salmon River earned its name "River of No Return" because early miners could only travel downstream, later cannibalizing their boats to build cabins in this isolated terrain. In 1980, Congress designated the area the Frank Church-River of No Return Wilderness, spanning 2.3 million acres with a gorge deeper than the Grand Canyon.
In summer 2014, a group of female veterans, all bearing emotional and physical scars from their service, embarked on a journey down this formidable river. Sponsored by an Idaho nonprofit called Higher Ground, these brave women all suffered from PTSD. I joined them to witness how wilderness might affect minds that had experienced severe trauma.
Wars leave signature wounds. Civil War survivors often faced amputations, WWI advanced facial reconstruction, and recent wars have left unprecedented rates of PTSD-affecting about 18% of veterans overall, with recent conflicts showing rates of 27%. Women experience PTSD differently than men, with higher rates of anxiety and eating disorders, while men show more aggression and substance abuse.
On the river, these veterans faced Class II and III rapids that demanded focus and courage. While kayaking creates brief, manageable adrenaline rushes, combat creates prolonged stress that permanently alters the brain. PTSD essentially functions as a memory disorder, with brain scans showing cellular changes in the hippocampus. The amygdala remains in hyperdrive, preventing distinction between real and perceived threats.
Despite their physical limitations, the women embraced the challenge. Marsha Anderson, despite nerve damage, learned to "breathe through" rapids after being ejected from her kayak. Tania Herrera discovered she could paddle with her one good arm, proudly contributing rather than being helped. The physical exertion, laser focus required by the rapids, and sensory elements of nature were already beginning to calm their nervous systems.
As the trip progressed, the group fell into a natural rhythm. Morning yoga sessions became a ritual, with even the most reserved participants joining in. Day by day, more laughter emerged. Herrera observed how the river experience paralleled military life: facing danger, depending on a tight group for survival, and finding meaning in simplicity.
There's a long American tradition of combat veterans seeking healing in wilderness areas, particularly in the backwoods of Idaho, Montana, and Alaska. Research by David Scheinfeld showed Outward Bound participants experienced 9-19% improvement in mental health compared to control groups. The wilderness setting encouraged veterans to open up about their experiences and become more receptive to traditional therapy. Higher Ground participants showed up to 40% decrease in PTSD symptoms.
As the group floated through landscapes showing both recent and older wildfire damage, they witnessed nature's resilience. Linda Brown, who had been institutionalized for depression, whispered: "The trees can't control their lives. We can't always control what happens to us. The trees can teach us acceptance. And metamorphosis."
第4章
Restless Minds: How Nature Transforms Children with ADHD
By second grade, Zack Smith couldn't stay seated in class. Diagnosed with ADHD, he cycled through ineffective medications and special classrooms, where his disruptive behavior led to suspensions. His parents withdrew him from traditional school after eighth grade.
Now fourteen, Zack found himself rock climbing in West Virginia with the Academy at SOAR, a boarding school for children with ADHD and learning disabilities. Despite initial awkwardness, he showed focus and determination. Before SOAR, Zack "hated nature" and preferred video games. But during a three-week horse-packing trip in Wyoming, something shifted. In the outdoors, his restlessness transformed into adventure-seeking-perhaps what it was meant to be all along.
Our brains evolved outdoors in environments with manageable novelty-everything nameable, from foods to creatures. We developed to notice distractions (avoiding predators) while maintaining focus (building tools, planning). This balance between attention and distraction became one of humanity's greatest evolutionary advantages.
Most ancestors had brains craving novelty and exploration, helping humans expand into diverse habitats. Evolution favored variability-some pushed exploration more than others, thriving in dynamic environments. But modern society pathologizes this once-adaptive restlessness, with ADHD drug advertisements warning of symptoms like "may climb excessively" or "trouble staying seated."
ADHD manifests differently between genders, with boys typically showing hyperactivity, impulsivity, and distractibility. Those with severe symptoms have different brain chemistry governing reward, movement, and attention. Easily bored, they seek stimulating activities that flood their brains with neurotransmitters like dopamine and serotonin.
Research consistently shows that dynamic outdoor learning environments benefit these children. As Erin Kenny of Cedarsong Nature School puts it, "Children cannot bounce off the walls if we take away the walls."
This philosophy traces back to Friedrich Frobel, kindergarten's founder, who in 1837 envisioned education immersed in nature. Walking through German forests, he conceived a system where children would absorb the natural world through all senses-growing plants, exercising outdoors, and learning through self-directed play with simple objects.
Modern European education still honors this tradition with over 1,000 German "forest kindergartens" and Finnish schools that send children outside fifteen minutes of every hour. In Scotland's Auchlone preschool, four-year-olds light campfires, handle tools, and learn through nature-based challenges-prioritizing "hazard assessment" over "risk avoidance."
At SOAR, many students arrive on medication and continue taking it. Though not designed to eliminate medication, some students like Zack find they can reduce their dosages after experiencing the program's benefits. His mother describes the changes as "miraculous."
Meanwhile, alarming statistics show preschoolers becoming the fastest-growing market for antidepressants in America. Teen anxiety and depression have increased five to eight times compared to the 1950s, and suicide rates have risen dramatically. Research shows that when children have access to green spaces, they naturally become more active and healthier.
第5章
Urban Oases: Creating Nature Where Most Humans Live
In 2008, humanity crossed a significant threshold when the majority of our species began living in cities, earning us the nickname "Metro sapiens." This urban migration continues accelerating, with projections showing 2 billion more people moving to cities within thirty years. While urbanization brings benefits like improved sanitation, education, and healthcare, it also presents significant challenges for mental health and wellbeing.
Research shows city dwellers experience 21% more anxiety disorders, 39% more mood disorders, and double the risk of schizophrenia compared to rural residents. Brain scans reveal increased activity in the amygdala-the fear center-and altered function in regions regulating stress. People living near industrial "gray spaces" demonstrate decreased coping strategies and less optimism.
Singapore offers a remarkable counterexample. The country dedicates 0.6 percent of its national budget "to develop scenery"-five times the proportional funding the U.S. National Park Service receives. Under fifty years of leadership primarily from Prime Minister Lee Kuan Yew, Singapore transformed into the world's third-most-successful economy despite having virtually no natural resources.
Lee Kuan Yew planted a public tree soon after taking office, launching what became a personal obsession. He initiated a "garden city" plan that evolved into a "city in a garden" vision. Today, half of Singapore's 276 square miles has some form of green cover-a percentage that's actually increasing despite population growth. By contrast, Washington D.C.'s tree canopy decreased from 50 percent in 1950 to just 36 percent today.
Singapore requires developers to more than replace any displaced nature through green roofs, integrated gardens, and parks over parking lots. The country aims to have 80 percent of residents living within 400 meters of green space, and they're already at 70 percent.
Trees emerge as our best tool for urban salvation. Frederick Law Olmsted understood this, ordering 300,000 trees for Central Park's 800 acres. Modern research confirms their value: when emerald ash borers decimated 100 million trees across the American Midwest and Northeast, affected counties suffered 15,000 additional cardiovascular deaths and 6,000 more respiratory deaths-a 10 percent mortality increase.
A Toronto study revealed neighborhoods with higher tree density had lower rates of heart and metabolic disease. Living on a block with just 11 more trees than average provided health benefits equivalent to a $20,000 income increase. Cities worldwide are now launching ambitious tree-planting initiatives, recognizing trees as critical solutions for carbon storage, heat islands, and air quality.
第6章
The Three-Day Effect: How Wilderness Resets Our Overloaded Brains
David Strayer, a cognitive psychologist at the University of Utah's Applied Cognition Lab and expert on distracted driving, has turned his attention to how nature affects the human brain. He gathered a team of neuroscientists to develop rigorous methods for studying nature's effects on cognition, aiming to measure how wilderness influences thinking, problem-solving and collaboration.
The group included skeptics like Brian Dyre, who questioned whether nature's benefits come simply from providing a diversion from daily cares-possibly no different than visiting a museum or listening to music. Despite his skepticism, he enjoyed the dramatic scenery of Arches National Park as the group hiked across slickrock fins toward Double O Arch.
After just half a day in nature, neuroscientist Adam Gazzaley experienced a creative breakthrough with his photography. This is exactly the kind of effect Strayer hoped to measure scientifically. His previous pilot study with Outward Bound participants showed a remarkable 50% improvement in creativity after just three days in nature.
Art Kramer, the senior neuroscientist of the group and director of the Beckman Institute at the University of Illinois, joined the team for dinner. Known for his groundbreaking research proving that exercise protects the brain from cognitive decline, Kramer represented what Strayer aspired to achieve for nature research. "In 1992, the exercise/brain literature was where the nature literature is now," Strayer explained. "My goal in the next ten years is to do for nature what he did on exercise and cognition."
As the scientists prepared for a hike in Hunter Canyon where cell service was unavailable, they debated whether nature's benefits stem from what it provides or what it lacks-namely, the constant interruptions of digital life. Paul Atchley suggested that "tech is leading us in a negative direction and nature may prevent that," citing research showing media multitaskers have impaired focus.
Their conversation turned to the concept of attention-what William James called "the taking possession by the mind." Attention comes in two forms: voluntary (task-focused) and involuntary (stimulus-driven). Our brains constantly filter the overwhelming amount of sensory information we receive, with most neural connections actually serving inhibitory functions.
"Attention is everything," explained Paul Atchley. "Without it, we don't see, hear, taste." This filtering process that allows us to focus consumes significant cognitive resources. Task-switching-something we do constantly in our digital lives-burns precious glucose that our brains need for both cognitive and physical performance.
Frederick Law Olmsted recognized in 1865 that nature "employs the mind without fatigue and yet exercises it; tranquilizes it and yet enlivens it." In the early 1980s, psychologists Stephen and Rachel Kaplan developed Attention Restoration Theory (ART), proposing that natural settings provide "soft fascination"-stimuli interesting enough to hold attention without demanding it. This allows our exhausted frontal lobes to rest.
Meanwhile, Roger Ulrich developed Stress-Reduction Theory (SRT), arguing that nature exposure immediately lowers anxiety and stress, then improves cognition. The Kaplans' approach emphasizes cognitive restoration first, while Ulrich focuses on emotional and physiological effects.
第7章
The Scent of Healing: How Natural Aromas Affect Our Bodies
In South Korea, the author explores how the country is medicalizing nature through its forest healing program. She visits Jangseong Healing Forest with Park Hyun-Soo, a former hospital manager who became a "forest healing instructor" after recovering from leukemia in the woods. The facility, one of three official healing forests with 34 more planned, hosts thousands of visitors monthly for therapeutic programs.
Park Hyun-Soo, a 41-year-old cancer survivor who left his corporate hospital job after finding healing in nature, guides the author through the forest. After a traditional Korean lunch and tea ceremony, they begin exploring the forest's therapeutic qualities. The facility measures visitors' physiological responses before and after forest experiences, building a database to quantify nature's health benefits.
The forest itself, once completely denuded after Japanese occupation and post-war scavenging, was replanted in the 1960s with hinoki cypress trees prized for their pest-resistant properties and distinctive aroma. Walking through feels like "moving through a picturesque vat of VapoRub," with the trees releasing phytoncides-airborne compounds that Park explains can reduce stress by 53 percent and lower blood pressure.
The author learns about geosmin, the compound responsible for the distinctive earthy smell after rainfall. Produced by soil organisms like streptomyces bacteria (which are crucial to many antibiotics), geosmin can be detected by humans in incredibly minute quantities-equivalent to seven drops in a swimming pool. This heightened sensitivity likely evolved as a survival mechanism, helping our ancestors locate water sources.
South Korea's "Peak Stress" phenomenon-despite having the world's 14th strongest economy and highest education rates, Koreans work the longest hours among OECD nations, with widespread depression and the world's highest suicide rate-has sparked a return to nature, reflecting Korea's ancient spiritual traditions where trees and mountains were venerated.
The author visits the Korean Forest Agency to understand South Korea's national commitment to "forest healing." She meets Minister Shin Won-Sop, who rose to prominence through psychology research rather than traditional forestry. Under his leadership, the agency has implemented an ambitious national forest plan to "realize a green welfare state," offering everything from prenatal forest classes to forest kindergartens and even forest burial options.
Our sense of smell is astonishingly powerful-humans can detect one trillion odors, including many we don't consciously register. The nose provides a direct pathway to the brain, bypassing the blood-brain barrier, which explains why scents trigger such powerful emotional responses. Our olfactory abilities evolved for survival, helping us detect food, danger, and even fear in others. But this superpower is diminishing-genetic evidence shows over half our smell genes have become inactive, compared to only 30% in wild apes.
第8章
The Soundscape of Wellbeing: How Natural Sounds Reshape Our Brains
In search of the elusive "calm alert" brain state dominated by alpha waves, the author discovers how difficult it is to find quiet in our increasingly noisy world. Environmental noise levels have been doubling every thirty years, with vehicle traffic tripling between 1970-2007 and air traffic predicted to increase 90% over twenty years. Sound engineer Gordon Hempton found fewer than a dozen places in the continental US where human-made noise can't be heard for fifteen minutes at dawn.
Our hearing evolved as our primary alerting sense-no vertebrate species has ever evolved to lose hearing. This explains why even during sleep, our bodies react to noise with elevated heart rates and blood pressure. Studies show these stress responses don't diminish with habituation but worsen over time. Research near airports reveals alarming health impacts: people living with noise above 46 decibels are twice as likely to need hypertension medication, and children show elevated stress hormones, reduced reading comprehension, and cognitive delays equivalent to being almost a year behind in the noisiest neighborhoods.
The National Park Service has a mandate to protect natural soundscapes, a nearly impossible task managed by their "Natural Sounds and Night Skies" division. Kurt Fristrup, the division's scientific coordinator, studies both noise pollution's harmful effects and the benefits of natural sounds. At Penn State University, researchers Peter Newman and Derrick Taff discovered that visitor surveys at Muir Woods revealed noise as a primary concern, with people using emotionally-laden words like "soothing" and "peaceful" to describe desired soundscapes. Their research led to the creation of a "quiet zone" in Muir Woods that reduced background noise by three decibels, effectively doubling the listening area. Most surprisingly, their studies found that human-caused noise makes parks appear 38% less scenic, while urban settings with birdsong are rated more attractive-proving that soundscape directly affects visual perception.
Of all natural sounds, wind, water and birds form the "trifecta of salubrious listening." Birdsong particularly affects us deeply-Darwin devoted more pages to it than human music in The Descent of Man. Birds sing in the morning, creating associations with alertness and safety, while their absence signals danger. Remarkably, humans share more genes governing speech with songbirds than with other primates, as both evolved similar language centers using ancient neural hardware-the arcopalladium in birds and the basal ganglia in humans, a region also regulating emotion. This neurological connection may explain our primal affiliation with chirps and trills.
Seoul's Cheonggyecheon stream exemplifies practical urban sound design-formerly an underground ditch, it was "daylighted" in 2005 as part of a greening initiative. Water is pumped in and recirculated through planted trees and shrubs that attract birds and insects, creating a natural soundscape that competes with traffic noise. Without such interventions, we risk what National Park Service's Kurt Fristrup calls "learned deafness"-tuning out the real world with earbuds and losing our ability to hear subtle natural sounds.
第9章
The Nature Prescription: Finding the Right Dose of Green
The author presents the "nature pyramid" concept developed by Tim Beatley, which offers a recommended dosage of nature experiences. At the base are daily interactions with nearby nature-birds, trees, fountains, pets, and natural elements in our surroundings. Moving up are weekly outings to parks and waterways where city sounds recede, followed by monthly excursions to forests or restorative natural areas. At the pinnacle are rare but essential wilderness experiences needed yearly or biyearly, which can "rearrange our very core" by catalyzing hopes, inspiring awe, and reassuring us of our place in the universe.
The author distills her findings into a simple coda: "Go outside, often, sometimes in wild places. Bring friends or not. Breathe." She notes encouraging trends as cities worldwide integrate natural elements into urban environments, particularly water features that our brains especially love. However, she acknowledges persistent inequality in access to green spaces, visible even from satellite imagery of cities like Washington D.C., where affluent areas appear green while low-income neighborhoods look gray.
Doctors are beginning to prescribe nature experiences, with pediatricians like Nooshin Razani and Robert Zarr creating partnerships with parks to help underprivileged patients suffering from conditions like obesity and depression. She argues that we profoundly undervalue our need for nature, evident in how we cut recess, design buildings that limit natural elements, and stay indoors.
Finnish research shows that just fifteen to forty-five minutes in urban parks improves mood and feelings of restoration. Studies recommend at least five hours monthly in nature for measurable benefits, with ten hours creating "a new level of feeling better." This can be achieved through thirty-minute nature visits twice weekly or "two to three days per month outside the city."
In Scotland, Richard Mitchell's research published in the Lancet examined 40 million English residents and found lower death rates in greener neighborhoods across all income levels. Most significantly, income-related health disparities were smallest in the greenest areas-poor people in green neighborhoods lived longer than their counterparts in less green areas. Later European studies confirmed that green recreational spaces reduced mental health inequality by about 40 percent.
The ancient concept of solvitur ambulando (in walking it will be solved) has been embraced by thinkers from Aristotle to Nietzsche. Walking in restorative settings has long been believed to generate mental clarity, inspiration, and even genius. As Rousseau wrote, "I can only meditate when I am walking. When I stop, I cease to think; my mind only works with my legs."
Modern research now studies awe as a core positive emotion with remarkable effects: Paul Piff's research shows awe makes people more generous, while Dacher Keltner found it uniquely lowers inflammation markers. The vagus nerve may physically mediate these experiences, connecting to oxytocin receptors and creating a "humming sensation" during profound awe experiences. Awe promotes curiosity by presenting experiences outside our normal frame of reference, drawing us out of ourselves and creating lasting memories.
