Nature: It Is Good for Us

Donald A. Rakow, an associate professor at Cornell School of Integrative Plant Science, was the featured speaker at Berkshire Botanical Garden's annual meeting on May 26. The following is a summary of his talk:

By Donald A. Rakow

Evidence has mounted that being active in nature can improve our overall health — psychologically, physiologically and attitudinally. 

One theory popularized by famed biologist E.O. Wilson and termed “biophilia” is that humans hold an innate connection with all other living things on earth. Wilson proposed that our deep affiliations with other life forms and nature are deeply rooted in our biology. He suggested that, as a species that originated as hunter/gatherers, we needed to be aware of other organisms to survive.

In her book, The Well-Gardened Mind, the psychiatrist and psychotherapist Sue Stuart-Smith writes: “When we work with nature outside us, we work with nature inside us. It is why people feel more fully alive and energized in the natural world, why gardeners report feeling calmer and more vigorous, and why spending time in nature awakens the connection-seeking aspects of our human nature.”

Nature doesn’t have to involve an extensive trip into a primeval forest. I grew up in Levittown, N.Y., a prototypical post-WWII suburb. Though properties were small, there were plenty of places to discover nature, including small woodlots, area parks and even our own backyards.

Nature can also serve as an affirmative social magnet, even in as dense an urban environment as New York City. As people relax in nature and feel comfortable and supported by it, the tensions and anxieties that can cause road rage or street disputes melt away.

“Being out and about on busy city streets means having to process a lot of auditory as well as visual information, and it disrupts our ability to focus,” Stuart-Smith writes. “Horns, sirens, alarms are all intended to put people on alert and keep them safe, but they drain our energy in trying to filter them out.”

This idea relates to the Attention Restoration Theory, first advanced by Steven and Rachel Kaplan in 1995, which focuses on the amount of time each of us spends in directed attention, such as staring at computer screens, engaging in conversation, listening to a lecture, or making our way along city streets. As a result of prolonged concentration, an individual may display signs of attention fatigue. By contrast, time in nature has been shown to relieve our directed attention, as we become more occupied with what the Kaplans call “soft fascination.” The result is improved cognitive functions, such as memory recall and the ability to perform concentration tasks.

An alternate theory was first proposed by Roger Ulrich in 1991 and is referred to as Stress Recovery Theory. Taking an evolutionary approach, this theory posits that our sympathetic nervous system is conditioned to respond to threats by increasing stress hormones and preparing us for “fight or flight.” Of course, that’s helpful if we’re about to be attacked by a wooly mammoth, but not so great in our current stress-filled world. Ulrich has proposed that natural settings activate our parasympathetic nervous system, allowing us to rest and digest.

Outdoor Exercise vs. Indoor 

Interestingly, other studies have compared the effects of outdoor exercise to indoor exertion. A 2013 study by Richard Mitchell concluded that “physical activity in natural environments is associated with a reduction in the risk of poor mental health to a greater extent than physical activity in other environments.” Another 2011 study by J. Thompson Coon and others concluded: “Compared with exercising indoors, exercising in natural environments was associated with greater feelings of revitalization and positive engagement, decreases in tension, confusion, anger, and depression, and increased energy.”

Phytoncides and Soil

But why does exercising outdoors compared with indoors result in more improved mental health and attitude? Researchers say one reason may be due to phytoncides, chemical compounds that protect trees and other plants from bacterial, fungal and insect attacks. As we absorb them through our nasal passages, these same compounds can also boost our human immune system, keeping it strong for days after a single outing. 

Ordinary soil can also benefit humans in ways that are just now being revealed. For instance, one study has shown that non-pathogenic bacterial compounds commonly found in soils increased levels of serotonin in mice (serotonin is associated with feelings of well-being and happiness) and decreased levels of anxiety.

Start Them Out Young

For all of you caretakers of young children, it’s important to know that many psychological authorities now believe that the window of opportunity to form bonds with the natural environment develops sometime during early and middle childhood and requires regular interactions with nature. Research has shown that contact with nature during the middle childhood years occupies a surprisingly important role in a child’s emotional responsiveness and social development. 

Yet a worrisome feature of contemporary society is that many children increasingly experience nature through electronic devices if they experience it at all. 

Moreover, studies have shown that habitual stress that develops in the middle childhood years can also follow young people as they progress from childhood into college. 

But there’s good news to share: As educators learn about the many cognitive and social benefits of spending time in green spaces, school yards across the U.S. are being transformed from concrete wastelands into living classrooms with the goal of helping nature become an integral, joyful part of children’s daily learning. 

Nature Rx 

As a university faculty member, I’m particularly concerned with finding ways to improve the mental and physical health of our college population — and to do so through promoting their exposure to nature. 

Several years ago, a group of us started Nature Rx@Cornell, dedicated to “reducing stress and thereby increase physical and mental health in students through their engagement with nature, and to cultivate in students an increased appreciation of nature.” Since then, the Nature Rx movement has taken off across the U.S., resulting in the Campus Nature Rx Network that currently includes nearly 60 colleges and universities. While each school has a unique approach to getting students active in nature, we are united in a belief in the fundamental value of such exercise. We put out a monthly newsletter and an annual fall virtual symposium.

Aging Population and Health

But what about our aging population? Around 14 percent of the population of the United States is aged 65 years or older. By 2060, that number is estimated to double. As the elder population rises, the benefits of living near green space become more apparent. At the same time, the number of people living in towns and cities hovers around 80 percent placing an even greater importance on both the availability of and easy access to urban parks and green space.

In a 2020 research brief, social scientist Kathleen Wolf and research scientist and landscape designer Elizabeth Housley reported that older individuals with access to nature showed increased participation in outdoor physical activities, improved mental health and cognitive function and an increase in social interaction with those around them and their community.

How Much Time in Nature Do We Need? 

Colleagues at Cornell and I have learned that as little as 10 to 30 minutes, two to three times a week, can significantly reduce cortisol levels, blood pressure and heart rate, increase cognitive ability and recall, and improve overall mood. And if that works for 20-year-olds, it should also be effective for the rest of us.

We cannot deny that we live in a time of turbulence, of social isolation and of environmental degradation. But through outdoor physical activities including gardening, hiking, jogging, swimming, boating, and skiing, we can each improve our own well-being and encourage those around us to do the same.