Rob Dunn

The Microbes Among Us

Air Date: November 2, 2018

North Carolina State scientist Rob Dunn discusses his new book “Never Home Alone: From Microbes to Millipedes, Camel, Crickets, and Honeybees, The Natural History of Where We Live.”


HEFFNER: I’m Alexander Hefner, your host on The Open Mind. Today we return to the natural world with the author of a new Basic Books volume, “Never Home Alone: From Microbes to Millipedes, Camel, Crickets, and Honeybees, the Natural History of Where We Live” Rob Dunn is a professor in the Department of Applied Ecology at North Carolina State University and in the Natural History Museum of Denmark at the University of Copenhagen. He is the author of five previous books including “Never Out of Season” and “Every Living Thing,” Dunn lives in Raleigh, North Carolina. “In the process of sanitizing our own homes,” Dunn reveals in “Never Home Alone,” “we’ve created a playground of revolution for bacteria and parasites in our not very tranquil homes.” His discovery of 200,000 new species living incognito in our bedrooms, kitchens, living areas, bathrooms, basements, attics, astounds. Some can kill. Some are benign and some may actually help us enhance our health, but most of them, if not all of them, until your investigation, Rob were unknown, to us.

DUNN: Yeah, so for most of history, I mean early on we figured out that there are some pathogens living in our house and so once we’d figured that out, most of the people who studied the indoors focused on the bad stuff and people like me trained as basic biologists, we’re taught to go far away and make new discoveries, and so I started off as a tropical biologist. I grew up in Michigan. I thought, where am I going to discover a new stuff, so I went off to jungles, but the truth is that that meant that all the stuff that wasn’t deadly in your bedroom and your bathroom, there was nobody really focused on it, and so it’s this whole realm we bump into every day that doesn’t have a sort of scientific domain of inquiry. There’s nobody in charge of it.

HEFFNER: And yet it’s a thriving biodiverse climate.

DUNN: Yeah, absolutely. This, this room, your socks, your suit, all of it is covered in life.

HEFFNER: What were the most pernicious examples to start with of resistant microbes that are perhaps the over-sanitation or reliance upon antibacterial soaps and fluids?

DUNN: Yeah, so I think that we get this idea that if we just clean and clean and we kill and kill, that we create a sterile environment and instead what we tend to create are these things that are really good at living under those conditions when we use lots of biocides, lots of antibiotics, lots of those antimicrobial wipes. And so what we surround ourselves with when we overuse those are things like MRSA, which is a kind of staphylococcus bacteria that’s resistant to some of our best antibiotics, including meticillin. We surrounded ourselves with roaches that are resistant to pesticides. And so we get this whole army of things that we don’t know how to kill.

And so that’s what we make in our sort of default way of living in apartments in New York or houses in Raleigh or, or what have you.

HEFFNER: What did you find though, was the most normal or the most? Let me put it this way, the best-case scenario for being clean and not further exacerbating the resistance.

DUNN: So the best-case scenario is actually super simple. It’s moderation. It’s washing your hands with soap and water when you go to the bathroom. It’s not overusing antibiotics, it’s not overusing an antimicrobials; it’s leaving your windows open when you can. And, and it’s figuring out ways to what a little bit of life back in, because it turns out we need that life to compete with those deadly microbes. We need that life to compete with the roaches. It turns out if you open your windows…

HEFFNER: So, fresh air, sunlight,

DUNN: So, fresh air, sunlight, wash your hands, like it’s really that simple. But we’ve built a whole civilization on the idea that we need to do much more than we need to seal ourselves off. And in doing so, we sealed off all the benefits of nature and kind of sealed ourselves in rooms like this one with some of the stuff that’s most dangerous for us.

HEFFNER: I hope not (laughs) but cleanliness is appreciating the biodiversity that is nurturing your home.

DUNN: Yeah. So.

HEFFNER: So you have examples of this from the showerhead, there are a lot of examples, but what were some of your favorites from your pretty comprehensive study of the home?

DUNN: So the showerheads are actually super duper interesting. So if you take off your showerhead, unscrew it. Inside that showerhead is a little layer of life that we call a biofilm, which is just a fancy scientist’s word for shower gunk.

And every shower had has that, right? So you can’t escape that you’re going to have some kind of biofilm living in your shower because basically what happens is the food that’s in the water goes to the showerhead, had kind of get stuck there and the microbes make this apartment of their own feces and then live off of that food. And so you can’t get rid of that, like it’s going to be there.

HEFFNER: And you shouldn’t try.

DUNN: Well, you shouldn’t try to get rid of it. You should try to figure out how do we control this stuff we don’t want in there and favor this stuff we do. And one of the things we’ve been able to show in looking at showerheads from around the world, which is kind of manage this fun project, we have people sampled this gunk from the Netherlands, from South Africa, you name it and send it in via ordinary mail.

But so one of the things we found was that in houses that chlorinated their water, so if you’re living in the New York, you know, water supply system with this super chlorinated water, that what happens in that water system is when the water gets to your showerhead, all this stuff that susceptible to chlorine has died. And what’s survived is this stuff that that’s not susceptible to chlorine actually sort of bad news stuff.

HEFFNER: What’s that stuff?

DUNN: And so like nontuberculous mycobacterium, which can cause infections in immuno-compromised people. It’s a crazy problem in hospitals. It’s a relative of tuberculosis.

HEFFNER: That’s what it sounds like…

DUNN: It’s not from a good family of things. And it’s, it’s super common in showerheads and it looks as though chlorination actually makes it more common.

HEFFNER: On the reverse side, what are you more susceptible to in Europe, if anything, by not having the chlorine?

DUNN: So the trick is you have to have a water system that is free of pathogens in the first place and so where the water’s coming from has to be free enough that you don’t have to treat it. And so in most places we’ve polluted our waters enough that that’s no longer true. And so if all that place that your, all of your water comes from, it’s still free of human pathogens or free of industrial toxins, then you’re okay. So there’s no tradeoff. The tradeoff only emerges when you have water systems that are at risk for pathogens or when you can no longer rely on the water that’s in the ground water and you’re using surface water, which happens in New York. Upstate New York, big lakes, a lot of water comes from there down in to New York City and it has to be treated because you’ve got beavers in those lakes. You’ve got all kinds of things going on. But ancient water underground where a lot of this European water comes from, it doesn’t always have to be treated and so it’s actually. It’s a hard situation because we can’t fix it super quickly once we screw it up.

HEFFNER: Is there a great unknown associated with non-chlorinated water because you might not know the origin. You’re essentially assuming the beaver or the bad actors who might molest the water quality when…

DUNN: Did you just called beaver a bad actor.

HEFFNER: I’m sorry, I’m sorry. The beautiful majestic, majestic is it a majestic actor…

DUNN: I think it’s sort of a majestic…

HEFFNER: It’s a cute actor.

DUNN: Yeah,

HEFFNER: So on the flip side though, just in terms of surveying water that has unknown associations. You have to be fairly confident that there is no ground molestation?

DUNN: Absolutely. Depends on having a good regulatory framework. It depends on somebody keeping an eye on the water and monitoring it. It depends on all of those things.


DUNN: But all things equal, if you could be in Munich where most of the groundwater, most of the tap water’s coming up from a deep ground water aquifer that’s been healthy for a long time and it’s full of biodiversity, things that keep the pathogens and control, it’s pretty good deal.

HEFFNER: Sure. So let’s go back to the home, the home environment, the most obvious location of where, you know, there’s growth is your refrigerator and the devices and appliances surrounding. Did you look in the kitchens? Were you surprised by anything in the kitchens?

DUNN: So in general, if you go around your apartment, what we find is like the first and most conspicuous thing is every place you go is sort of covered in the falling apart of you.


DUNN: And so it’s all the microbes associated with your body. And this, by the same token, your fridge is full of things that are associated with the falling apart, rot of your..… I don’t, I have not seen your fridge but one’s fridge in general… Laughs.

HEFFNER: But what beyond on a more microscopic level, a strand of hair, what are we talking about? What of you, is there.

DUNN: Well, millions and millions of skin cells are falling off and rotting those skin cells are bacteria. These little mites that ride with the bacteria, like both of us have at least one species of face mite, probably two, they live in your hair follicles and they mate on your face during an average day. And so everybody that works with you next time you look at them, remember that that’s happening, so all of that’s going on, all of that falling off around you. And mostly that doesn’t matter at all. Most of that stuff dies where it lands and it’s of no real negative consequence to you. But the interesting stuff becomes the species that are living in weird habitats in our homes. And so for example, if you go from the fridge to the freezer, we see microbes in people’s freezers that have only been discovered in the Arctic or Antarctic. And so our homes are also full of these super unusual habitats.

And we don’t know anything about what’s going on there. Your hot water heater, there’s a microbe in hot water heaters that’s only been found in hot water heaters and in hot springs. And so in building homes and building these weird little niches that around our houses we have created this whole new world that we’ve paid very little attention to. Each pocket has its own stuff.

HEFFNER: What do you want us to do with our homes now that we’ve made these discoveries?

DUNN: So, I think, I mean, one of the things we had to pay attention and start studying the life in our homes and we did a study a few years ago where we asked people if they haven’t, this is a bigger thing. Camel crickets in their houses and it’s a, it’s a cricket the size of your thumb. Nobody studies them. And we got, data back almost immediately.

And what we saw was that where people who said they had these crickets was not where they were. They were in the wrong places. They were all on the east coast; this and you’re missing it from the west coast. And so we asked people to send pictures and we thought people are just sort of misidentifying what was in their house. And it turned out what was going on was that there was a giant Japanese camel cricket the size of like a full thumb that had moved house to house across eastern North America without anybody noticing it. Everybody thought somebody else knew what it was. And so it’s super common and we estimate 140 million of these camel crickets in homes. And so when we found that out, people ask, well, what do you do about that? Like, what good is it? And as a scientist, I’m trained to hate the question, what good is it?

But so we thought, well, how can we look at a species like this and other species you find in your house? How can we search for the values they might have? And so we thought, well, this is a kind of cricket that lives in caves usually it; it eats hard to break down things. What if it has microbes in the gut that allow it to eat those things? What if we could use those microbes industrially? And so we looked for microbes in the gut of those camel crickets and one from my basement in particular that might break down plastic or the waste of the paper pulp industry and so far from all of earth there are only five species of bacteria that can break down the stuff that is produced by making paper. We found five more and the first individual camel cricket we looked in and so my sense is that as we grow around our homes, that there are all these species that we know nothing about, each one of which could offer some huge value to society and, but we won’t ever know unless we pay attention.

And then in general, the more we seal ourselves off inside our homes, that’s the same relationship we have to nature in general, that we’ve stopped paying attention. And so we’ve stopped seeing the answers that can provide.

HEFFNER: The Union of Concerned Homemakers is what we need.

DUNN: Exactly.

HEFFNER: But I don’t know why you disliked that question or maybe you’re just being facetious because evidently a lot of good can come from the studies of our homes to identify microbes that might help us with environmental stewardship in the case of cutting down on plastics or in our ongoing efforts to defeat cancer or other disease. Were there were there other examples?

DUNN: Yeah, I actually was being…

HEFFNER: I know you’ve, my scientific process should be undeterred by a desire for some x, y, or z solution.

DUNN: It’s how I’ve been trained and I think it’s, it’s a huge mistake and it’s part of why we’ve missed some of these obvious things.

But yeah, another one would be in the super common ants in homes in New York and we think some of those ants are producing new kinds of antibiotics.


DUNN: There are, like what’s another example? So a transgenic corn, the genes in that transgenic corn that produce pesticides come from a moth, but from a kitchen cabinet in Germany. And so again, in the end we find useful things. Penicillin used to produce antibiotics. It’s the same bread mold you find in your house, and so I think that you know, of the hundreds of thousands of species around us everyday, many of them have potential uses.

HEFFNER: What do you advise in terms of surface area and what I was getting to before, the seeming necessity today to clean virtually every surface area. You said before, common sense, moderation is the right approach, but to me the pretty standard approach is to swipe every surface area imaginable with a Clorox wipe.

DUNN: Yes. I think maybe one way to think about this is to think about what happens when you use a Clorox wipe and what we imagine happens is that you kill all the life on the surface that you used the wipe on, so if like we used to on this table, we imagined that in doing so, the table becomes sterile. Instead what we’re doing is we’re killing all those things that are susceptible to the wipe.


DUNN: And even in the second after you remove the wipe, there’s still life here. It’s just the stuff that the wipe can’t kill, and so every time you’re using one of those,

HEFFNER: you’re further bolstering the unkillable,

DUNN: Favoring a subset of unkillable things.

HEFFNER: So you prefer the brands that are not antibacterial.

DUNN: Yeah. So that’s one simple answer. So the antimicrobial compounds as opposed to soap and water, what soap and water does is it washes off the most recently arrived things and it leaves intact the other things. And so when you wash your hands with soap, you’re getting rid of the pathogens that you just got by shaking somebody else’s hand, but your good microbes stay on your skin. And the same is happening with other surfaces.

HEFFNER: You said on the flight over you couldn’t help but imagine New York City and this gigantic bedbug…

DUNN: Yeah. Right.

HEFFNER: What, what did you say? You saw the bed bugs from 20 thousand feet in the air.

DUNN: Well, it’s like you fly over New York and it’s just amazing, right? Like this amazing expanse of city of grandeur and, and, of habitat.

HEFFNER: Right. And what about bedbugs? What did you find in the bedrooms?

DUNN: So, we found a lot in the bedrooms and I can’t talk about all of it, but the so in general, bed bugs are another one of these things that we favored by using pesticides, we favor resistant bed bugs. The more we kill them with pesticides, the more resistant they become and everything else goes away, or, to take another example, the German cockroaches. So it used to be the case that you could put out a fructose bait, a little bait. The German cockroaches would go into the bait, they would eat the sugar and then they would die. A couple of years ago, somebody found cockroach bait and they put it out and the roaches didn’t even go toward it. It turned out what had happened is that the roaches have actually evolved to hate sugar. And so we’re mismatched in this war, like we’re not even close. And so I think we think like, well, we’re so sophisticated, we will just outwar them well out chemical them. And that’s not what nature is like. I mean,

HEFFNER: That’s a lot of discretion there for that cockroach.

DUNN: When you can watch you put, you put the bait out, they walk up to it, they’re like fruit fructose, I’m not interested.

HEFFNER: So here’s what I want to talk about in our remaining time, the differences in the scientific method in Europe today as compared to the United States. I mean you have a pretty defined idea of scientific investigation and what it means to be rigorous and have integrity and some provable thesis that you’re getting at, but what have you found in society’s application of science in Europe where you teach and interact with the scientific community versus home base in Raleigh? What do you find to be either a unifying consciousness or differences and have they emerged recently or are they longstanding differences?

DUNN: Yeah, that’s a good question. I mean, so it has a bunch of layers and one is that the way people worry about germs in the life around them differs in the public and so there’s the public differences, which are interesting.

HEFFNER: But what are those?

DUNN: Well, so for example, that water systems are treated super differently and so most Austrian water is coming straight from in Vienna is coming straight from the aquifer untreated with chlorine,


DUNN: Huge difference and there’s a lot of comfort with that biodiversity that’s flowing through the tap. Versus we’re very much of this, you know, we’re going to kill all of nature and if it comes back again, we’ll use a bigger hammer model and sort of industrial model of the home. But science itself also differs. And so one recent example is that there’s a bad kind of fungus, the black toxic black mold that people are worried about a lot in homes, and actually can cause a lot of problems.

We don’t know a ton about it, but one of the questions that keeps emerging is where does it come from in the first place? And Birgit Andersen at the Technical University in Denmark figured out that where it appears to be coming from is drywall that least in European drywall, probably in American drywall, when you buy it, brand new, it already has this mold inside it, and so when that drywall gets wet, the mold then just grows and, and so that work could have been done in the US, but my suspicion is that people will be a little bit scared to publish work suggesting that Drywall, this thing we use, billion dollar industry is potentially sneaking something into our homes that we don’t like. And so there are differences in the perceived power of industry and how science relates to it that I think are pretty big from country to country.

HEFFNER: And is it true or false that the more enforceable regulatory scheme in Europe hinders scientific endeavor? Or is that a wrong stereotype?

DUNN: I think in general it’s a wrong stereotype.

HEFFNER: A lot of people would, people who are a view the American system as unfettered exploration capitalism, especially in the current political environment, they might form that, but, how do they balance the regulations and scientific endeavor differently in Europe?

DUNN: So I think we’re fettered by different things, right? That the European model, there’s more constraint on one views is as ethical as permissible and the societal context. Transgenic crops will be one example. What kind of transgenic work do you do? By the same token in the US, I think that there’s much more awareness of the power of industry and that the kind of work one can do in light of that power. And then there’s two elements. One is fear, right? Like do I do this research given that this is work that could threaten a very, very powerful industry of whatever type, and the other is money and so a huge proportion of university money in the US comes directly from industry and so, which is not to say that that corrupt scientists but, but it means a lot more work is going to happen in those things that industry already views this as a reasonable to work on, right? The drywall industry is not going to find like, can we find fungus in drywall? The clothing industry is not going to fund like are there ever pathogens on clothes when you buy them new.

HEFFNER: So it to those folks, it’s not a socialistic impulse, it is an ethical, moral view of your fellow human being from the European context that you want to do research that furthers the livelihoods of people and not corporations, is that more of the salient feeling.

DUNN: Yeah, And to really search for beautiful truths in a way that’s not compromised by big dollar industry money.

HEFFNER: And maybe from the inception because the original funds are not from those corporations.

DUNN: Right.

HEFFNER: So the process can, can work differently.

DUNN: I mean the money is an attractor in science and so if you put money over here, science will move that direction. Right? And, and so in part what we do and don’t know about houses is reflected in that.

HEFFNER: What do you hope might reform in the American system in response to your book beyond what we’ve talked about, which is lay folks like me in our response to the growth of bacteria or biodiversity in our homes. What do you think that the American system ought to consider importing some of the values of the European scientific model?

DUNN: Well I think there are two kinds of questions there. So, one, what do I hope, I mean, I think an immediate hope would be that we find ways for scientists to connect with the public, to study the life around them every day that people have been missing in a way that can excite kids, that can make discoveries relevant to everyday life and that can push us forward in big ways. The other question is about the broader scientific endeavor. And it’s so bound up by culture and policy that I think it’s easier to envision small changes than it is to envision the US system becoming the Danish system or the German system. They’re so different.

HEFFNER: Have you personally felt hindered in the American system as someone who’s accomplished a great deal?

DUNN: Have I personally felt hindered… there are

HEFFNER: In your scientific pursuits…

DUNN: Yeah, I guess the way to frame it, for me personally, it would be that there are kinds of questions that are way easier to ask because it’s way easier to find funding for them. And so implicitly that’s hindering another kind of question that are, that are, nobody’s funding, or nobody wants to quite see the answer.

HEFFNER: Well, your university, and we actually hosted another scholar of hip hop from NC State, Ninth Wonder, some months back, seems to be producing some really magnetic and important investigation.

DUNN: And we’ve got fleas and that kind of hip-hop in the houses. And then we’ve got the other. We cover hip-hop.

HEFFNER: We talked about how R and D research and development from those companies is what leads to the incentives that propel investigation. So what, if anything, are those companies cognizant of when it comes to the blowback from their use, if we think of the Clorox’s’ and the Lysol’s?

And are they aware of what you document in your book?

DUNN: Yeah, we’re probably not good friends I guess. Well, so as an example,

HEFFNER: How could you work in tandem though, is could you envision working in tandem? Because that’s really how you describe the American model.

DUNN: Yeah. That’s a good question. That’s a good pokey question for the end. But yeah I think one model is to think about how to more strategically use those compounds being produced by industry to kill bad things when we know they’re there, not using them indiscriminately in a way that also kills the good stuff we need and that’s inevitably going to lead to less use, right, and so the in tandem model is a little bit difficult there.

HEFFNER: Or use of alternatives that they also produce.

DUNN: Right? Yeah.

HEFFNER: Professor pleasure being with you quite animated.

DUNN: It was a great joy. Thanks for having me.

HEFFNER: Thank you Rob and thanks to you in the audience. I hope you join us again next time for a thoughtful excursion into the world of ideas. Until then, keep an open mind. Please visit The Open Mind website at to view this program online or to access over 1,500 other interviews and do check us out on Twitter and Facebook @OpenMindTV for updates on future programming.