I’ve divided the book into five parts to help make sense of the
material, and to make it useful. The first part sets up the two
dominant theories that attempt to explain why our brains need nature
and that drive much of the research: the first chapter takes us to
Japan, where researchers are quantifying nature’s role in lowering
stress and boosting mental health using a framework based on the
biophilia hypothesis, the idea that we feel most “at home” in nature
because we evolved there. The second chapter swerves over to Utah,
where American neuroscientists are more interested in how nature
helps restore our attention-addled brains to a state of sharper
cognition. I’ve organized the rest of the book by nature dose. I
explore the immediate effects of quick bursts, or “nearby nature” on
our three main senses—smell, sound, sight. Then I look at what
happens to our brains and bodies when we hang outside a bit longer to
approximate the Finnish recommended nature dose: five hours a
month. In Part Four, I take a deeper, longer dive into the wilderness,
where really interesting things happen to our brains. This is where, in
the words of neuroscientist David Strayer at the University of Utah,
“something profound is going on.” Finally, we’ll look at what it all
means to the way most of us live, in cities.
Throughout, there will be insights into how we can better
construct our days, lives and communities so that everyone gains.
Don’t worry; I’m not going to tell you to pitch your smartphone over
a waterfall. The world we live in is fully plugged in. But it’s
important to call out just how radically our lives have shifted indoors
—and what those changes mean for our nervous systems—so that we
may hope to ease and manage the transition.
My move to the city is a micronarrative of the demographic and
geographical shifts occurring on a global scale. Homo sapiens
officially became an urban species sometime in 2008. That’s when
the World Health Organization reported that for the first time more
people throughout the world live in urban areas than rural ones. Last