“The difference is in language,” he continued. “If I ask you, ‘Is a
human a dog?’ you say, ‘No, a human is not a dog.’ In Japan, we say,
‘Yes, a human is not a dog.’ The great sensei of nature research
peered at me over his chopsticks. I was reminded of the story of the
Zen student who asks his teacher, “How do you see so much?” and the
teacher responds, “I close my eyes.”
Miyazaki’s answer, I understood, was like a koan, tantalizing and
confounding at the same time. But you had to trust the guy was onto
something.
THE NEXT MORNING, the college boys and I took turns sitting in the
mobile lab at the trailhead. We placed hard cotton cylinders under our
tongues for two minutes, then spit them out into test tubes. That
would record our levels of cortisol, a hormone made in the adrenal
cortex. We got hooked up to probes and devices. The team was
inaugurating a brain-measuring, battery-powered, near-infrared
spectrometer that, when deployed, gave me a sensation of leeches
sticking to my forehead. We’d repeat all these measurements at the
end of the walk and again in the cityscape.
To gauge our physiological responses to these environments,
Miyazaki and Lee look at changes in blood pressure, pulse rate,
variable heart rate, salivary cortisol and, new this year, hemoglobin in
the brain’s prefrontal cortex. When aggregated, these metrics paint a
picture of our bifurcated nervous system. When we are relaxed and at
ease in our environment, our parasympathetic system—sometimes
called the “rest and digest” branch—kicks in. This is why food tastes
better in the outdoors, explains Miyazaki. But the demands and
constant stimuli of modern life tend to trigger our sympathetic
nervous system, which governs fight-or-flight behaviors. And trigger
it, and trigger it. We suffer the consequences: a long trail of research
dating back to the 1930s shows people who produce chronically high
cortisol levels and high blood pressure are more prone to heart