November 06, 2018

Rob Dunn

“We still don’t know all of the species in the average house.”
Dunn’s Never Home Alone will change the way you look at your house. Our homes—no matter how much we scrub, spray and clean—are a rich, biodiverse environment, filled with insects, bacteria and life that has yet to even be discovered. Dunn explores the life that can be found in our homes not with disgust, but with wonder. You will no doubt be surprised by how helpful this unseen world can be to us and how dangerous our obsession with sterility can be. We asked Dunn a few questions about microbial misconceptions, beneficial molds and dog mouths.
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Rob Dunn’s Never Home Alone will change the way you look at your house. Our homes—no matter how much we scrub, spray and clean—are a rich, biodiverse environment, filled with insects, bacteria and life that has yet to even be discovered. Dunn explores the life that can be found in our homes not with disgust, but with wonder. You will no doubt be surprised by how helpful this unseen world can be to us and how dangerous our obsession with sterility can be. We asked Dunn a few questions about microbial misconceptions, beneficial molds and dog mouths.

What was the most surprising thing you learned in your research into the biodiversity of our homes?
I’ve been working on homes for more than 10 years now and, again and again, the thing that surprises me is how little we know. Every day we breathe in thousands of species from the air in our homes. A few of them are dangerous (very few). A few are extraordinarily beneficial. Most don’t have names and have never been studied by anyone, ever. When I was a graduate student, scientists talked about completely inventorying a tropical rainforest, finding and studying every species. That would be an amazing accomplishment, but it is a century away. We still don’t know all of the species in the average house. I know these things, and yet, each time some totally new phenomenon emerges (we recently found extreme and strange microbe species in salt shakers, for instance) I am surprised. Gobsmacked by wonder.

Why did you decide to write this book now?
We have spent 10 years studying the life in homes, and it was becoming increasingly clear that the public perception about such life and what we were learning were totally at odds. It seemed time to share what we were beginning to understand. I could have waited 20 years, until we knew more, but I wanted to share this particular moment when we have begun to see, through the haze of our collective ignorance, an outline of what is going on, but many of the individual mysteries remain to be resolved. I wanted to share some of those mysteries so that readers could begin to help study them, too.

For example, the timing is perfect for us to engage readers in helping us to study the animals in houses around the world.

What good are household critters like meal moths and camel crickets to us?
Nature can be extraordinarily useful, and we have done such a bad job searching for nature’s values to humanity that we can find totally new values even in species living right around us. The first antibiotics, of course, came from bread molds. Bread molds saved us from some of the deadliest pathogens! Until we realized their value they were just there, an ordinary problem in the pantry. By the same token, meal moths (another problem in the pantry, albeit a rather beautiful one to my aesthetic) have proved to have bacteria in their guts that have transformed, totally transformed, agriculture. Wasps, of the sort that nest on eaves and in windows, have proven to have novel yeasts in their guts that make totally new kinds of beers. And in camel crickets, we have found bacteria that are able to break down waste from the paper pulp industry. All of this is to say that if we pay attention to the species around us all the time, literally underfoot, they can often offer societal solutions that in their benefits vastly outweigh any nuisance we might perceive. In part, this is because any species can offer such value, but also because some of the unique features of the species in our houses may make them more likely than chance to have such values.

Is there any real harm in letting our dogs lick us on our mouths?
Ah, tricky question. Depends on what your dog licked before it licked you. If your dog licks feces and then licks your mouth, well, it probably isn’t great. That said, at the same time we know that in some cases, children are missing key gut microbes that they can receive from dogs, and the process of such “acquisition” is probably just such a smooch.

You point out that “favoring biodiversity is like making bread or kimchi.” What do you mean by that?
In making fermented foods, such as sourdough bread or kimchi, we have found ways to favor communities of organisms that contain wild species. But they are wild species that are living in a way that simultaneously excludes pathogens. The acid produced by the microbes in kimchi or sourdough starters kills pathogens. The alcohol in beer kills pathogens. These foods are both biodiverse and self-regulating. We need to develop ways to favor communities of species around us that are wild and wondrous and, ideally, like these foods, also help to keep the less wondrous (at least from our perspective) species at bay. Bakers and cooks are better at this than modern medicine is. We can learn from the deliciousness they have wrought.

You mention “rebooting and rewilding” our gut. Can you talk a little more about that?
Fecal transplants are becoming common. They vary in their details. But basically what happens is that someone is given a dose of antibiotics and then an “offering” of the fecal microbes of another, healthier, person. This rewilds their gut with microbes that might have gone missing because of overuse of antibiotics or for other reasons. It is incredibly effective in a number of medical contexts, but it is also, of course, primitive. We don’t yet know which species of microbes we need, which ones are going missing, and so we regrow the whole forest. It is both a huge advance—a life-saving advance—and a measure of our humility before the grandeur of nature.

Can you talk a little bit about how our mania for keeping our houses clean can make us sick?
It is really pretty simple. If we clean, madly, obsessively, constantly, as many of us do, we never, ever, ever, ever kill all of the life around us. Instead, we kill the most susceptible life. We kill species that are the ones most likely to benefit us (or to be benign). What we leave behind are the toughest, weediest, most problematic species. We inadvertently garden dangerous species, species resistant to antibiotics and pesticides, species we can’t control. When you see a hyper-sterile environment, scrubbed recently with antimicrobial wipes (for instance), what you should think is not “clean” but instead “haven for resistance.”

What lessons would you like readers to take from your book?
Our lives only make sense in light of nature, we only make sense when we remember that we are ALWAYS embedded in nature. We can try to create sterile lives lived amidst sterile homes. But we will fail and, in our failure, make ourselves ever sicker with evermore unusual chronic diseases. We need to keep deadly pathogens at bay, but most of the life around us is not deadly. Most of the life around us is wondrous, mysterious and potentially beneficial. Open your windows again. Throw out your antimicrobial wipes. Start fermenting food. Embrace biodiversity in your home, and in your backyard, and in your life.

Author photo by Amanda Ward

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