obesity. Now, though, he’s turned to the environment itself. Long
fascinated by why some places breed healthy people and some places
don’t, he was intrigued by research in the Netherlands to start looking
at maps of green space. Dutch studies had shown remarkable mental
and physical health benefits of living within half a mile of green
space, including reductions in diabetes, chronic pain and even
migraines. Mitchell wondered if one of the main reasons for the
association was simply exercise.
This assumption makes sense. When we are out in nature, we are
generally self-propelled, breathing in oxygen, liberating our lungs and
our cardiac capillaries from their usual cramped, desk-hunched
configurations, and arresting, temporarily, the slow backward death
march of our telomeres. Exercise as a cure for all things has been so
drilled into the public health establishment that it crowds out
everything else, with the possible exception of quitting smoking and
washing hands.
So Mitchell read the first wave of large European studies about
the restorative effects of nature with a great deal of eye rolling. Those
studies, published in the early 2000s, linked nearby greenery to
everything from longer lives and fewer chronic diseases to higher-
birthweight babies. There were simply too many confounds, as he put
it. How could any scientist possibly attribute health to nature when
the people most likely to be near nature were already healthy, already
exercising, already relatively wealthy, and so on? Take Mitchell
himself: he grew up tromping around the moors near Exeter in the
1980s with his mum and dad. He read National Geographics in the
attic, played bass guitar and enjoyed an early form of geocaching
outdoors called letterboxing. His parents suggested he become a
scientist, so he did. It would be as preposterous to say it was the
windy fens that made him a success as it would be to credit his
favorite ham sammies.
Beyond the confounds, “It’s easier to understand exercise than