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Guest Blog: How Our Health Is Tied To A Healthy Planet

Nathanael Johnson is the author of All Natural: A Skeptic’s Quest to Discover if the Natural Approach to Diet, Childbirth, Healing, and the Environment Keeps us Healthier and Happier. He will be at Seattle’s Town Hall on Feb. 6, and Powell’s Books on Hawthorne on Feb. 7.

by Nathanael Johnson

When you’ve just finished a book examining at the idea that what’s natural is healthy, you get a lot of people asking, “So is natural good or not?” It would be nice if there were a simple answer to this question, but of course, it’s far more nuanced (and I think, far more interesting) than that. Here are three ways in which the health of the earth does seem to be tied to human health, each complete with at least a little bit of complexity.

Autoimmune diseases

With autoimmune disease there’s strong evidence that our alienation from the natural world is hurting us. In the last few decades, the rates of multiple sclerosis, type 1 diabetes, and Crohn’s disease have doubled, tripled, even increased by an order of magnitude in some places. Almost half the people in First World nations now suffer from a combination of allergies, asthma, and eczema.

The theory to explain this is generally called the “hygiene hypothesis” but I think the “old-friends” hypothesis (a name proposed by the scientist Graham Rook) is more appropriate: The idea is that we evolved in the company of old friends—microbial companions that accompanied us so unswerving through our evolutionary journey that human genetics incorporated them, building immunological bulwarks on their backs. Certain gut parasites seem to keep the human immune system from attacking itself, and children who live on farms in close contact with other animals (and their microbes) are less likely to have asthma and allergies. Human health relies, to some extent, on communion with other species.

Mental health

Why are people living in cities almost twice as likely to develop schizophrenia?

Why are people living in cities almost twice as likely to develop schizophrenia?

Here the data is much softer: It’s hard to find objective measures of mental health and nearly impossible too trace a line from cause to effect. All the same, the evidence is at least intriguing enough to consider.

It’s been suggested that prevalence of schizophrenia boomed with the industrial revolution, though this is predicated on imprecise, historical accounts. Much more solid is the evidence that people in cities are almost twice as likely to develop schizophrenia as people living in the country. Then there’s Richard Louv, who has assembled various bits of science suggesting that children may develop “nature deficit disorder” and not function as highly if they don’t get a chance to play in the wild.

When humans use tools to transform their environment it’s usually to plane nature’s complexity down to Cartesian simplicity: to plow a riotous field into furrows, to break a tangled forest down to regular boards—then build it up again as a grid of perpendicular walls. The psychiatrist Ian McGilchrist has proposed that an industrialized environment promotes a hyper-logical mode of thinking, which could lead to mental illness in excess. In other words, leave the city, and the brain has a chance to breathe. Anyone who moves between a built and natural environment will recognize a certain relaxation, a melting away of problems that had previously seemed all-important, as they step out into the wilderness. Again, all this is somewhat fuzzy, but interesting, and worth taking seriously.

Food and farming

Foods with longer shelf life are often less nutritious and loaded with ingredients that are linked to diseases.

Foods with longer shelf life are often less nutritious and loaded with ingredients that are linked to diseases.

The evidence that small, environmentally responsible, organic farms produce crops with more nutrients is tenuous. And yet, it’s almost guaranteed that you are eating healthier if you are supplied by a farm like that than by the industrial food system.

That’s because our modern system requires foods that remain enticing even after they have traveled long distances, lingered in warehouses, traveled some more, and finally waited on supermarket shelves.

Adding large amounts of sugar, salt, or fat—and removing fiber—keeps foods from spoiling, while also providing a certain no-brainer appeal. The cravability (to use a food-industry term) of a candy bar lasts longer that the subtle flavors of a well-grown tomato. Nutrition is still a young science, but no one thinks it’s a good idea to eat a high-carb, high-fat, low-fiber diet. It’s clear that the oil-powered, monoculture-based, pesticide-heavy mode of agriculture has fed the rise of obesity and type 2 diabetes.

One final, local, example to muse on

 One study found mothers living near trees were less likely to have babies with low birth weight.

 One study found mothers living near trees were less likely to have babies with low birth weight.

In Portland, a study showed that women living in neighborhoods with lots of trees were less likely to have low-birth-weight babies, even after controlling for their economic status. No one has any idea what mechanism could link baby health to trees, and I’d want to see the study reproduced a couple of times before I fully trusted the finding, but it makes a certain intuitive sense: Leafy neighborhoods just feel good.

And this makes me wonder. I’d started by asking how the health of the earth is related to human health, but by the end I was questioning what I meant by a healthy earth. Perhaps the idea of a “healthy earth” is anthropocentric, in the most virtuous possible sense—an earth that makes us feel good. That is, perhaps our idea of a healthy environment is really a vision of nature that provides the ecosystem services humanity needs to thrive: clean air, clean water, plentiful food, and ample opportunity for natural wonder and delight.

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