When you think about your childhood, what are your strongest memories? Many of mine are associated with the time I spent playing outdoors, climbing trees and “treasure” hunting alongside a creek. My family always had a big vegetable garden, so I remember picking beans; an orchard of pear and apple trees, a grape arbor and a walnut tree added to the richness (and to our summer diet). Now I live in Seattle. My watershed is Longfellow Creek, and I live near the crest of a hill, the first ridge encountered by weather fronts coming across Puget Sound.
My yard has its own microclimates; we can grow tomatoes on the parking strip to the south, but are hard pressed to ripen any but the shortest season tomatoes in the yard proper. Carrots, chard and potatoes do better. We have an ancient apple tree that shades us in the summer, letting in green-tinted dappled light. I often have the urge to thank the tree for sticking around. It’s not very “wild” nature, but it grounds me in a place where I belong.
I’ve been thinking a lot lately about why that matters, and especially why it matters as we become an increasingly urban species. We need nature; not just for the air we breathe, for the water that constitutes most of our bodies, and for the sun that warms us and provides energy and the earth that feeds us, but also for the way it enables us to be fully human and a part of the whole that surrounds us.
Biologist E.O. Wilson coined the term “biophilia” to refer to this innate affinity that humans have for nature, the love of capital-L Life. And in the past few years, I’ve been heartened that we appear to be rediscovering just how important that connection with nature is. A number of research studies have reinforced what appear to be instinctive affinities with scientific data, and connecting nature with health has broadened the field of interested designers and citizens considerably.
Across a range of themes, the findings are interesting:
Perception and Context: Although the frequency and sound patterns of freeway noise and ocean waves are very similar, our reactions depend upon our associations. A 2010 study by Hunter averaged the two and played them for listeners to determine their physiological responses through functional magnetic resonance imaging. When accompanied by beach images, the sound induced brain patterns consistent with tranquility, but the same sounds, when accompanied by images of freeways, did not. 
Simulated Nature: Another study by Peter Kahn and team at University of Washington exposed subjects to three different scenes – a blank wall, a plasma screen “window” (a webcam image of the landscape outside), and an actual window looking out into the landscape. Subjects were exposed to several creative and proofreading tasks, and their stress recovery (heart rate) was measured. When confronted variously with these scenes, their recovery heart rate reduction leveled out similarly with both the blank wall and the plasma window, but was significantly greater when exposed to the real window.  Real nature means something to us.
Forest Bathing: Shinrin-yoku, or “forest bathing,” the practice of spending time relaxing in the forest, has taken hold in Japan and research is noting the benefits. One study measured the amount of human natural killer (NK) cell activity before and after forest bathing, finding that greater NK activity, increased anti-cancer proteins and reduced stress were the outcome of time in the forest.  Another study shows that even five minutes in nature improves self-esteem and mood. 
I’m aware of the inherent conflict in quantifying something so seemingly intangible, and it’s true that we need to be careful about boxing in something that can be such a source of delight and liveliness. But our era carries a thirst for data that challenges us to a greater rigor of execution. It may be that we swing too far to the quantifiable on the way to creating places that make our hearts sing, but I have hope that we will find that balance, and that our work and our cities will be better for it.
Most importantly, if we are to thrive in our societies and our cities, nature must be a necessary participant. I dream of the day when we hear birdsong more often than traffic, and pollution has made way for the clean crisp scent of snow, the heady fecundity of blooming trees in the spring, or the often pungent odors of rotting leaves at fall’s end. I yearn for the time in the future when we can barely see cities from Google Earth, expecting to find them beautifully intertwined with forests, meadows or wetlands. I hope I see a time when even urban dwellers know their watershed, and understand what creatures belong there, and find their own place full of Life to love.
 Neuroimage. 2010 Nov 1;53(2):611-8. doi: 10.1016/j.neuroimage.2010.06.053. Epub 2010 Jun 30.The state of tranquility: subjective perception is shaped by contextual modulation of auditory connectivity. Hunter MD, et al.
 Kahn, P.H., Jr., Friedman, B., Gill, B., Hagman, J., Severson, R.L., Freier, N.G., et al. (2008). A plasma display window? The shifting baseline problem in a technologically-mediated natural world. Journal of Environmental Psychology, 28, 192–199.
 Li Q. Effect of forest bathing trips on human immune function. Environ Health Prev Med. 2009 Mar 25. (http://forest-medicine.com/page11.html)
Image courtesy of Flickr.