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"If we don't always start from Nature we certainly come to her in our hour of need." (Henry Miller, 1957)
One of my favorites books is Eva Selhub's Your Brain on Nature: The Science of Nature's Influence on Your Health, Happiness and Vitality (the Kindle edition can be seen here). Each time I go back to it it gets colored with more day-glow highlighters. Thus, I was happy to learn about two recent studies that support Dr. Selhub's conclusions about just how good it is for us to get off our butts and get outside.
Walking in nature changes the brain
An essay by Gretchen Reynolds in the New York Times called "How Walking in Nature Changes the Brain" summarizes the results of a study by Gregory Bratman and his colleagues titled "Nature experience reduces rumination and subgenual prefrontal cortex activation" published in the prestigious journal Proceedings of the National Academic of Sciences. The abstract for this extremely interesting study reads as follows:
Urbanization has many benefits, but it also is associated with increased levels of mental illness, including depression. It has been suggested that decreased nature experience may help to explain the link between urbanization and mental illness. This suggestion is supported by a growing body of correlational and experimental evidence, which raises a further question: what mechanism(s) link decreased nature experience to the development of mental illness? One such mechanism might be the impact of nature exposure on rumination, a maladaptive pattern of self-referential thought that is associated with heightened risk for depression and other mental illnesses. We show in healthy participants that a brief nature experience, a 90-min walk in a natural setting, decreases both self-reported rumination and neural activity in the subgenual prefrontal cortex (sgPFC), whereas a 90-min walk in an urban setting has no such effects on self-reported rumination or neural activity. In other studies, the sgPFC has been associated with a self-focused behavioral withdrawal linked to rumination in both depressed and healthy individuals. This study reveals a pathway by which nature experience may improve mental well-being and suggests that accessible natural areas within urban contexts may be a critical resource for mental health in our rapidly urbanizing world.
A quick summary of the significance of this study is, "Participants who went on a 90-min walk through a natural environment reported lower levels of rumination and showed reduced neural activity in an area of the brain linked to risk for mental illness compared with those who walked through an urban environment." Mr. Bratman notes that the results of the study “'strongly suggest that getting out into natural environments' could be an easy and almost immediate way to improve moods for city dwellers." This surely is good news for those whose frenetic lives leave little time for a stroll. And, there appear to be no downsides to taking a short break and getting out in nature.
Street trees can make people healthier
The other study that came across my desk by Omid Kardan and his colleagues is called "Neighborhood greenspace and health in a large urban center" and was published in Scientific Reports. This essay is available online. The abstract reads:
Studies have shown that natural environments can enhance health and here we build upon that work by examining the associations between comprehensive greenspace metrics and health. We focused on a large urban population center (Toronto, Canada) and related the two domains by combining high-resolution satellite imagery and individual tree data from Toronto with questionnaire-based self-reports of general health perception, cardio-metabolic conditions and mental illnesses from the Ontario Health Study. Results from multiple regressions and multivariate canonical correlation analyses suggest that people who live in neighborhoods with a higher density of trees on their streets report significantly higher health perception and significantly less cardio-metabolic conditions (controlling for socio-economic and demographic factors). We find that having 10 more trees in a city block, on average, improves health perception in ways comparable to an increase in annual personal income of $10,000 and moving to a neighborhood with $10,000 higher median income or being 7 years younger. We also find that having 11 more trees in a city block, on average, decreases cardio-metabolic conditions in ways comparable to an increase in annual personal income of $20,000 and moving to a neighborhood with $20,000 higher median income or being 1.4 years younger.
An essay by Jason Goldman in Conservation Magazine called "Street Trees Really Do Make People Healthier" also provides a good summary of this study in which it is noted, "But a close look at the data offers up a suggestion. It wasn’t proximity to trees in a neighborhood that was the most important variable, but the number of trees on the streets. That suggests that it’s not necessarily that the trees are themselves providing important services (they do that, though that might not be what accounts for these health effects). Instead, it could be something as simple as peoples’ ability to literally see trees, and the most common place for most people to see trees is on the street. It’s also possible that street trees are disproportionately responsible for capturing street pollution, and that could be driving the team’s findings."
Rewilding our hearts is easy to do if we take the time to do it
These two studies are very much related to what I wrote in my book Rewilding Our Hearts: Building Pathways of Compassion and Coexistence. Here, I noted that it really is easy for people to get out into nature and reconnect with all sorts of habitats and landscapes. And, now, these two studies show how easy it really can be and how beneficial it is for our brains and for our health, including our heart. There don't seem to be any downsides to rewilding our hearts.
Marc Bekoff's latest books are Jasper's story: Saving moon bears (with Jill Robinson), Ignoring nature no more: The case for compassionate conservation, Why dogs hump and bees get depressed, and Rewilding our hearts: Building pathways of compassion and coexistence. The Jane effect: Celebrating Jane Goodall (edited with Dale Peterson) has recently been published. (marcbekoff.com; @MarcBekoff)
Reference:
Henry Miller, 1957, Big Sur and the Oranges of Hieronymus Bosch. New Directions Publishing Company, New York, p. 93
Note: In an email to me Wooster College's Dr. Susan Clayton, a renowned conservation psychologist, wrote about the first study, "... although I’m not sure it’s a fair test of nature’s benefits to compare it to walking by a highway. How about a comparison to walking on a treadmill, or through an uncrowded shopping mall? Or have people walking through nature while hearing traffic noises through headphones, and vice-versa?" I hope this line of research will be pursued.
