The wild indoors

It all began with a spider. A jumping spider to be precise. It was December—four months ago. It was cold outside, toasty inside. It was the first morning we awoke in our new house—a house we had spent years dreaming of, and more than a year building. It was built with as much local material as possible—hemlock from a nearby mill, quarried stones from our land and several nearby places. It was sited to make optimal use of the movement of the sun and minimize exposure to the wind and cold, as well as blend in to the landscape of old pastures and dairy barns. It was also nearly empty. We had moved in with only our bed, some toiletries, plates, cups and a coffee maker to get us started.

I was sitting on the floor of this spartan environment, looking out at the snowy meadows, trees and mountains I had long loved when I saw it: compact and rugged, traversing a large window. What? How do we have a spider in our less than 24-hour-old dwelling?

I wasn’t angry, the way I am in spite of myself whenever I see a cockroach in our New York City apartment, just perplexed. I’ve come to accept spiders indoors as generally good. From what I understand, they take advantage of much of the indoor insect population that we don’t like or want, even cockroaches, as food. But I thought I’d go the winter without contending with indoor insects. I hadn’t even gone one day.

After reading Never Home Alone: From Microbes to Millipedes, Camel Crickets and Honeybees, the Natural History of Where We Live this week, I have an appreciation for just how naïve I was.

First off, even without reading applied ecology professor Rob Dunn’s marvelous book, I recognize that the spiders likely moved in and established themselves when the house was being built—it was much more porous then to the surrounding rural environment. Jumping spiders are common. Spiders could also have arrived with building materials as they were delivered, or with the numerous contractors who worked on the house over the previous 14 months, stowed away on their tools, in their food coolers, even on their clothes. If I look at it this way, the spiders have even more right than I to be perplexed. We, essentially, moved in to their home.

Dunn, who leads a research group at North Carolina University, is one of a handful of ecologists who studies the life inside our homes—the way that “one might inventory a rain forest in Costa Rica or a grassland in South Africa.” This alone is unusual and cool. He and his colleagues have now sampled thousands of homes across the U.S. and the world for all manner of living things: from animals and plants, to insects to fungi and bacteria.

We expected to find hundreds of species; instead we discovered—depending on how we do the math—upward of two hundred thousand species.

More species of bacteria have been found in homes than there are species of birds and mammals on Earth.

With this in mind, I decided to look a little more closely at my own home, starting with spiders.

…every house we have ever sampled—be it in Raleigh, San Francisco, Sweden, Australia, or Peru—has contained spiders. The question is not whether spiders are in your house controlling pests, it is whether you have enough spiders, of the right species, to do the job well.

I found two other spider types during a rather lazy (or perhaps tentative) search in my heightened state of indoor awareness. When I vacuumed, I found two logy flies and a dead wasp in the window sills, and when I dusted, discovered half a dozen winged insects of various sizes I’d never noticed before. This, according to Never Home Alone, is just the tip of the iceberg.

Nearly all of the houses sampled contained at least a hundred species of arthropods [insects]…Some had many more, up to two hundred species.

I found living things I could actually see. Dunn describes water, as in, the water from our two wells that we use for drinking, bathing and cooking as teeming with microscopic life.

Every bit of water that has ever sprayed down on you from the shower, risen around you in the bath, or poured into you from a glass or a sealed bottle has been full of life. As is so often the case with the life in homes, what differs from one house or tap to the next is not the presence of life but instead its composition, which species are present and what those species do.

While the required testing of our well back in November showed that we were within safe health limits on coliform, arsenic and iron, Dunn explains that water, especially from underground aquifers, is likely to contain high numbers of bacteria, protists and even tiny crustaceans. And that’s, apparently, a good thing! In an intrepid study of showers and shower heads, Dunn and his colleague Noah Fierer looked at the biofilm, or thin sludge, that builds up there over time. They discovered that municipal water systems, which tend to use a high amount of chlorine or chloramine to reduce the risks of harmful bacteria in the water supply, result in shower head biofilms with much higher amounts of mycobacterium—a family of bacteria which includes Mycobacterium tuberculosis, the bacteria that causes tuberculosis. (Mycobacteria are resistant to chlorine. And to be clear, Dunn did NOT make the case that people are exposed to TB from shower heads.) But some mycobacteria strains from shower heads are thought to be responsible for other lung illnesses as well as eye and skin maladies, especially in immune-compromised people.

Interestingly, they cite another researcher, Christopher Lowry, who has determined that exposure to one type of mycobacterium, called Mycobacterium vaccae, correlates to higher serotonin levels in the brains of mice and humans. Higher serotonin means greater well being and less stress—increased resilience. Clearly, the life forms in our water paint a mixed picture. Our attempts to render water “clean” are not always delivering the best outcomes, it seems.

The drywall installed in our house, regardless of where it came from or who manufactured it, according to Dunn, contains numerous fungi spores. If activated by moisture, they include one called Neosartorya hiratsukae, now thought to contribute to the complex of factors that lead to Parkinson’s disease, and the famed Stachybotrys chartarum (aka black mold), long associated with potentially dangerous allergies or pulmonary complications for people who live in houses where it has been found growing. Dunn’s colleague Birgitte Andersen, who undertook and continues the study of fungi in drywall, hypothesizes that it’s the very process of making drywall—usually from recycled cardboard—that introduces the largely inert fungi into our homes. We don’t suffer the consequences unless our drywall becomes wet, allowing those spores something to feed and grow on. Even without drywall, however, fungi of all kinds are abundant in homes. Dunn and his collaborators found 40,000 types of fungi from their DNA analysis of dust samples from homes around the U.S. and the world. (And, for context, fewer than 25,000 types of fungi are even named in North America.) Fungi are everywhere, and they are the “grand masters of destruction” when it comes to wooden homes. But as Dunn points out elsewhere in Never Home Alone, fungi are useful and necessary—specific fungi are known to aid in fermentation, giving beer, kimchi, and even bread their composition and character. Fermented foods support good health.

Dunn’s overarching point, regardless of what microbial and other living hazards may be lurking in our homes, is that “we need biodiversity in order to be well.” And that, in our modern efforts to live in homes that won’t make us sick from a small collection of known pathogens—even though that likelihood is quite low—our drives to be “clean” have introduced ways of being unwell in entirely new ways.

For example, chronic inflammatory diseases, life-threatening food allergies and even some autoimmune diseases like multiple sclerosis have been proven to have roots in a lack of exposure to wild species of bacteria, fungi, bugs and plants.

I’m in awe of Dunn and his colleagues and their work. I’m also left wondering how “healthy” my new, relatively sterile-feeling home actually is. Most of all, though, I’m reminded why I shifted my life to being more full-time in a rural place to begin with: because it’s more wild here.

The “wild” that I’ve always responded to in this place high in the Catskills region is outdoors: the native plants and animals along with the more open spaces that support them. Aside from the mental perks that come with spending more time outdoors and observing what happens there, I have always had a strong sense that interacting with soil, plants and to some extent animals delivers greater well being. Now, after reading Never Home Alone, I’d go as far as saying greater health. So while I’m excited to get my tomatoes, cucumbers and kale growing in the nutrient rich soil of this old dairy farm, and to get my bees moved to their new bee yard near the newly planted orchard, I’m as excited to make my own sourdough and sauerkraut for example, as well as open the windows and doors of this new home and let more of that wild in over time.

Thanks to Dunn and his book I’ve come to understand that wild matters in a way that I’d never fully considered before. The wild indoors. This haiku, which appears in one of Dunn’s chapters about insects, goes out to my new arachnid friends.

“Don’t worry, spiders,

I keep house

Casually.”

—Kobayashi Issa