August 11, 2020 • 46 mins
Most of us have spent far more time at home this year, which raises the question: Just what sort of artificial interior environments have we created? What lives there besides our family and pets? And what are we missing out on? In this episode of Stuff to Blow Your Mind, Robert and Joe explore.
Learn more about your ad-choices at https://www.iheartpodcastnetwork.com
See omnystudio.com/listener for privacy information.
Mark as Played
Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:03):
Welcome to Stuff to Blow Your Mind production of My
Heart Radio. Hey you welcome to Stuff to Blow your Mind.
My name is Robert Lamb and I'm Joe McCormick. And
today we're gonna be taking a look at interior spaces. Yeah,
the year certainly brings to mind the old curse, May
(00:23):
you live in interesting times? And one of the factors
here has of course been the coronavirus COVID nineteen pandemic,
and in an effort to fight the spread of the illness,
save lives, and prevent overwhelming our hospitals, we've made a
lot of changes to our lives and these range from
the simple such as just wearing a mask when you're
out in public and you can't social distance from people,
(00:45):
to the harder choices about employment and uh in life choices,
we've all been social distancing and stay at home orders,
teleworking and quarantine have meant that we've all been spending
a lot more time at home now. Depending on your home,
this could mean a lot of things, but we wanted
to explore what this means from a biological standpoint for
(01:07):
the most part here now now, make no mistakes, spending
more time at home has absolutely been the right move.
But just as it's forced you to focus more on,
say that weird staying on your ceiling, we wanted to
focus on the other, often unseen aspects of life in
the home right much the same way that being say
on a Spanish galleon out in the middle of the
(01:27):
ocean might have made you pay much more attention to
the biology and behavior of of ship rats than you
ever would have otherwise. I think being at home more
and more is forcing all of us to turn our
eyes and maybe our microscopes and magnifying glasses to the
corners and the cornices, and the shower heads and the
drain traps and all of the wonderful places in our
(01:49):
house where life dwells. Yeah, we're gonna really get into
the difference really between the natural world outside of our
homes and the unnatural world inside, and get into some
ideas about how how we could perhaps enable our interior
world to be a little more on the natural side
of things. But before we get into all that, I
(02:11):
wanted to take a moment here just to discuss the
history of houses in general, you know, just to get
into the concept of what a house is. Our our
first and still most important interior artificial environment. So you
can certainly look at a home as an artificial cave
to a certain extent. And indeed, we have lots of
(02:31):
early evidence that early hominids sought out shelter in caves
in the same way that many other animals do. UH.
These can shelter one against the elements and against predators,
And as recently as a hundred and thirty thousand years ago,
cave dwellers were already augmenting these natural interior environments with
things like rough stone walls. They were using timbers so um.
(02:55):
So you know, even a hundred thirty thousand years ago,
we were taking naturally occurring interior space paces and making
them a little less natural. Um. And of course, on
top of just the shelter that caves can provide, it
also seems that caves had a strong sacred meaning to
many of these UH prehistoric peoples. Those might be important,
but ultimately proximity to water is far more important. Thus,
(03:19):
as Kate Spence and Brian M. Fagan point out in
UH in the section of the seventy Grade Inventions of
the Ancient World about homes, most early hominids lived out
in the open near streams and lakes, they built temporary structures,
and most of this has been lost to time, but
some of the earliest evidence of potential structures for homes
(03:39):
goes back one point seven two point seven million years
ago with Homo erectus sites in southern Africa, and these
were potentially contemporary with the domestication of fire um and
these would have been temporary tents, but but they still
would have been artificial interior environments. Now more secure evidence
(03:59):
come from the Ukraine roughly forty four thousand years ago,
the mammoth bone structures from Maladova, which we recently discussed
on the show. Actually, yeah, we did uh talking about
these uh. That would have been structures in one of
the northernmost habitable regions of the Earth at the time,
because this was during a time of glacial advance where
(04:21):
the polar ice caps from the north were coming deep
down into Europe and Asia and uh and so this
would have been far far north, way up among the
ice and for some reason humans were building these structures
out of the bones of mammoth and we don't know that.
There's still things we don't know about those structures, like
how how consistently they were inhabited and for how long
(04:42):
and so forth. Right Now, beyond this, the history of
human homes is is largely dictated by local resources and
a local climate. A long process of trial and air
ends up leading to the development of regional and cultural
building forms construction methods. But before nine tho see we
see evidence of clay houses in Palestine and what is
(05:03):
today Palestine, and before seven thousand b C. We see
rectangular dwellings in Anatolia. But but at home is far
more than just a shelter. As the authors here point out,
houses became key to social structure as well. They point
out that the ethnographic studies in West Africa reveal complex
(05:23):
and layered symbolic associations and rituals in the context of dwelling,
and that this is it shows that a clear role
of physically structuring and expressing the relationship between different members
of the household. And we see this of course in
um and cultures. You know, throughout history and throughout the world.
There's this physical shape of the place, uh, and then
(05:47):
that ends up defining or influencing like that, there's this
this feedback between the two. It goes both ways. Right,
it's kind of like pouring a liquid into a container. Oh,
of course. And this actually got me thinking about how
having permanent, constructed dwellings must have changed the way that
power and hierarchy are expressed in social groups. And of
course this is true with normal social status. You know,
(06:10):
it's it's staked out through displays of wealth. There certain
kinds of taste or aesthetics in your house, your apartment,
your you know, your living space. But this also made
me think about the way that for many leadership positions,
there is a special house, there's a special dwelling place
that comes with the job, rather than belonging to an individual.
So here in Georgia we have the governor's mansion. There
(06:33):
is the White House there, you know, the palace that
the king stays at in many cultures, and there's a
there's a strange metonomy that derives from this. Often the
house identified with the position of power is used as
a metaphorical stand in for the person, you know, like
today the white House said such that, like, the permanent
(06:53):
dwelling place is actually almost the source of the power,
and there just happens to be a particular person living
there right now. Yeah, it's weird. We get so used
to it because it's just part of our daily um,
you know, our daily you know linguistic world. You know,
you can read the news, you read about these various locations,
these houses, and it's almost as if they have some
(07:15):
sort of intrinsic power to them, right, I mean, if
you weren't familiar with their cultures, you would read this
then and people might think, oh, well, they they clearly
thought that this big, white um house had some sort
of magical powers and whoever was allowed to go inside
it became the ruler of a country and got to
do whatever they want. Yeah, And it's funny that it's
so normalized for us, like we've forgotten to notice that
(07:37):
that's weird that like the power is somehow linked to
the house itself. Um. But it also makes me wonder,
you know, did we think about power differently before living
in artificially built environments? Yeah? To what extent did we? Um?
Did we end up yet changing the way we live
our lives by altering this physical environment which we live?
(07:58):
I mean it makes sense, right, because so much of
what we do, you know, it's dictated by the environments
that we evolve to thrive in right. So anyway, I
don't think we need to remind everyone about the value
of a home. Housing tends to be one of, if
not the most expensive parts of your life, but it's
it's interesting to think about them not simply as this
valuable thing in your life, for a valuable location where
(08:20):
your life takes place. The basic idea of the house
may be as old as our mastery of fire, and
it forms out of and forms ideas of who and
what we are, and of course it may do so
in more and more powerful ways every year, as humanity
slowly transitions to become a more indoors e on average species.
(08:41):
All the time, I was reading some interesting figures about
this trend in a book by the science writer Emily
and This uh in the book is called The Great
Indoors The Surprising Science of How Buildings shape our behavior, health,
and happiness. This is a really interesting book and I'm
going to refer to it throughout this episode because she
has an early chapter that's very good about the microbial
(09:03):
ecology of indoor spaces. But she also gets into some
interesting territory about the trends in how much built environment
and floor space we're actually creating. Obviously, this currently varies
a lot by culture and climate, but in some parts
of the world human kind is transitioned to an almost
entirely indoor existence. And this really shows in the way
(09:26):
we've transformed our environments to convert to this largely indoor existence.
Uh Anthes writes, quote, the island of Manhattan is only
twenty three square miles in size, but has three times
that much indoor floor space. And furthermore, she refers to
a report put together by a United Nations commission in
(09:47):
which concluded that over the next forty years, humankind is
going to roughly double the amount of indoor floor space
that exists currently. And the way this works out is
quote those additions are equivalent to building the current floor
area of Japan every single year from now until Wow.
(10:08):
That much floor is going to take a lot of
pine sawl Yeah. I mean it is crazy to think
about how certainly during pre pandemic times, you know, you
would you had this home, this interior space that you
live in, you sleep in, you bathe in, you spend
time in, and then uh and it is you know,
very much like the center of your life. And then
(10:31):
you're getting into another interior space, which happens to be
motorized and on wheels, and use that to travel then
a certain distance to another interior space that you'll go
into to work, either set at a desk or you know,
work with some sort of machinery or what have you. Uh,
and then at the end of the day back into
(10:51):
this uh, motorized interior space and then return to the
one in which you live. It's worth remembering yet again,
biologically speaking, this is not normal. This is not like
what our bodies are naturally adapted to. Spending this much
time indoors is still fairly historically novel, and it is
very weird. Yes. But the other big thing, and this
(11:13):
is going to be a recurring theme throughout the rest
of the episode, is that these artificial spaces that we made,
they are they're not completely alien, you know, they're they're
constructed all of the natural world. They're not the natural environment,
but they are made out of it. And uh and
and much of the natural world is still present, just
(11:35):
in um rebalanced and unbalanced ways. Uh. So that that
is going to be what we're going to really get into, Like,
what in creating these interior spaces, what sort of environments
have we created? Right, Indoor spaces are not unnatural in
that they're completely separate from the rest of the world,
but they're also not just like outdoor spaces. They're kind
(11:57):
of like a special niche environment, like a like a
cliff face or an island. You know, it's a place
where you have to investigate. Okay, what kinds of life
from around and other places are going to colonize this space? Yeah?
And and who are your roommates? Who are your inhuman
roommates in this space where you've been trapped? Uh these
(12:18):
past several months. Well, maybe we should take a break
and then when we come back, we can start talking
about those in human roommates. All right, we're back, so uh.
Rob Donne, a professor of applied ecology at North Carolina
State University and Raleigh, wrote an excellent book titled Never
Home Alone. From Microbes to Millipedes, camel, crickets and honey bees,
(12:43):
then Natural History of Where We Live. That's a nice
long title. I know you'd be like those those long
coland titles, want like a whole paragraph after the colon,
but it's it's it's hard as they go. It's pretty
good title. Anyway, it came out last October and it's
currently available in all format. So however, you read your books.
But I remember hearing an interview with the author around
(13:04):
the time that came out, and I picked it up
for this episode because it's, yeah, it's it's it's just
a very well written book and it really gets into
some just crazy, uh mind bending facts about these artificial environments,
most of which we won't even really be able to
get into in this episode, but we wanted to touch
on it. So if you look around its science papers,
you'll find Dunn's name um all over the place when
(13:27):
it comes to this area of microbial life. For instance,
he's the co author on a two thousand eighteen paper
that found that chimpanzee tree top beds, which are like
a daily affair, contained fewer microbes and Arthur pods than
human beds, which is not shocking given again the the
idea that ore beds that are kind of like set
(13:48):
in place, Um, you know, we will change the sheets,
but it's not every night probably, whereas the chimps are
going to be refreshing things a bit more. Also, thirty
of the bacteria in human beds stem from our own
bodies and includes fecal, oral, and skin bacteria. Yeah. The
way I heard it put, because this is covered in
Anthesis book too, is that with the with the human bed,
(14:11):
basically you're just gonna find tons of human type stuff
in it. But for a chimpanzees bed, you will find
you know, bugs, arthur pods, and microbes in in this bed,
but they're almost all from the surrounding environment. Uh. The
way it was put was that you might not be
able to tell that a chimpanzee had ever been there. Right,
very strange. But from Anthesis book there's uh So there's
(14:35):
a chapter that discusses a lot of the work of
the same researcher, robbed On, the the ecologist at North
Carolina State, but also a researcher that he's collaborated with
a lot named Noah Fierre, who's a microbiologist at u C. Boulder,
And there's a part where it talks about a survey
that they tried to conduct called the Wildlife of Our
Homes Project. There was a pilot study they started in
(14:57):
North Carolina, and so they would do was they would
get a bunch of families to take cotton swab samples
of seven different surfaces from inside their homes, and this
would include a countertop, a cutting board, a refrigerator shelf,
a pillow case, a toilet seat, a TV screen, and
then the trim around an interior doorway. And the results
(15:20):
were interesting. They found more than two thousand types of
microbes in these samples, and there were distinct microbial habitats
within the house. So perhaps on surprisingly, kitchens would have
a lot of bacteria that are naturally associated with food
that might be you know, found on food or aid
in the decomposition of food. Meanwhile, doorways would have a
(15:42):
lot of environmental species stuff you might find outside the house,
you know, things you would find on plant leaves and
in the soil. But then this was the quote that
really stuck with me, And this writes quote from a
microbiological perspective, toilet seats and pillow cases looked strikingly similar.
But we're dominated by bacteria that typically live on our
(16:03):
skin and in our mouths. All right, So that's that's
kind of a shocking sounding statement that might make you
want to instantly go and wash your pillowcase and maybe
your toilet seat too. But but but hold on, wait
till we get through the whole episode, because I think
one of the big tacomes here is like, if you
think that your pillow is going to be a microbial
(16:23):
sterile um experience, you know you should think again, likewise
with the toilet seat, likewise with anything in the house.
So in Dunn's book, one of one of the things
he drives home is that again our our house environments
are again not natural environments, but they are made out
of the natural environment, and they are not cut off
from the natural environment. So what we end up with
(16:44):
is an artificial environment that kind of mashes up all
of these various environmental parameters, sometimes in surprising ways, especially
when it comes to microbes, because if we as we've
discussed on the show plenty of times before, there is
no microbe free living our bodies, independent of anything else,
our home to multitudes of microbes. To come back to
a quote that we've pulled up on the show in
(17:06):
discussion in the past. In a Life in a World
without Microbes by Gilbert and Newfeld published in PRST Biology,
the authors contend that quote it would be false to
claim that macroscopic life cannot exist without microbes. However, although
life would persist in the absence of microbes, both the
quantity and quality of life would be reduced drastically. So
(17:27):
Done points out that even the outer layer of our
skin is just this rich microbial environment. Our armpit bacteria
are essentially fed by glands nurturing what has likely been
an historically important microbe passenger. And we can we can
look at this as an example of the sort of
microbe that then thrives in our creative environments. We tend
(17:48):
to find the same bacteria uh that that that thrives
in our under arms living in our homes, especially homes
where males live. If there's like a predominantly male population
of a house sold, you will find this particular bacterium.
I believe it's uh corn a bacterium just thriving Coarina bacterium,
Coarina bacterium. Yes. Yeah, So this thing about the sex
(18:11):
composition of the household versus the household microbiome was also
mentioned in anthesis book, and it's very interesting. So just
as you say, homes with more male residents tend to
have higher counts of bacteria such as Rosa burria and
this is commonly a gut bacteria, as well as Karina
bacterium and Derma bacter and uh at this points out
(18:34):
that these are most common on the skin. Now, Coarina
bacterium is often found in the armpit. As you say,
it is a contributor to body odor. But also it's
been found that just on average, men tend to have
more Coarina bacteria on their skin than women do, and
men tend to shed more skin microbes into the environment
than women do. And then on the other hand, households
(18:56):
that have more women living in them tend to have
higher counts of Lactobacillus, which is our old friend from
the fermentation episode. I don't know if this translates to
a workable difference, maybe not, but it makes me wonder
if it's possible that houses occupied by higher numbers of
women might be a better place to make sauerkraut. Interesting,
just some to think about, but sort of. What this
(19:18):
suggests is that humans are walking fountains of microbes. We
we shed our microbial passengers everywhere we go, and it
turns out this can be kind of quantified to creepy levels.
So consider this. No two people's microbiomes are exactly the same.
Each person is a unique ecosystem. So if everybody has
(19:41):
their own unique profile of microbiota, and everybody is shedding
microbial life all the time, are we essentially leaving identifiable
microbial evidence of our presence everywhere we go, you know,
kind of the slug trail of our microbiome all over
the place. And the answer appears to be kind of yeah.
(20:01):
At this reports one study led by Jack Gilbert at
the University of Chicago. I think that might be the
Gilbert of the Gilbert and Neufeld study that you mentioned
a minute ago. But it followed three families that were
in the process of moving into new homes. And what
Gilbert and colleagues found was that each family began to
(20:21):
colonize the new house with their microbes within just hours
of arriving there. Uh. And that the researchers quote could
even detect the individual microbial contributions of each family member. Uh.
And then Gilbert says, people who spent more time in
the kitchen, their microbiome dominated that space. People who spent
(20:42):
more time in the bedroom, their microbiome dominated there. You
could start to forensically identify their movement. Oh wow, So
this this makes one try to imagine like law and
order microbiology, yes, surveillance biotech. Yeah. But to come back
to to Rob Dunn's example about Corina bacteria in homes,
(21:06):
especially where males live. You you had an interesting thing
about that, Yeah, because he brings up a very curious
case of of an interior environment in interier home that
had a predominantly certainly at the time of the study,
had a predominantly male um population, and that is the
International Space Station. So this was basically there was a
(21:29):
study of the micro buyouta one finds inside the I
S S. This was conducted in two thousand thirteen by
Jonathan Ien, a microbiologist at u C. Davis. So, the
the I S S done rights, is very much like
a house on Earth. Quote, in nearly every way, the
bacteria of the I S S are the sorts of
(21:49):
bacteria we would expect in a house on Earth if
all the environmental influences were removed. I S S is
what you get when you scrub and scrub and close
the windows, doors and hatches. So the I S S
might be kind of like a very well scrub department
in a high rise in a big city. Yeah, I mean,
there's there's no outside to get inside, right, Um, I
(22:11):
mean immediately so obviously, um, stuff can be brought up,
but anyway, done also points out that in this study
of iss microbes, quote, everything was everywhere. The interior was
just codd in human bacteria, and nothing from outside was
getting in. Obviously. He points out that in a small
traditional home made out of mud and leaves, which would
(22:34):
have been you know, the normal for the vast uh,
you know, the vast majority of human existence, everything would
be everywhere as well, but environmental microbes would be everywhere.
What's outside would be inside. But for the I s
s there there is no outside. Really, it is a
you know, this sterile environment that is then inhabited by
human beings certainly, but then inhabited populated by human microbes.
(22:57):
So so environmentally sterile, but heavily colonized by what the
humans bring with them, right, He writes, quote, if you
scrub and scrub your home, this is what you may
achieve too. It is not unlike what we see in
some apartments in Manhattan, And as we and others have
begun to study such apartments, we have found a problem.
(23:17):
The problem is not what is present, but instead what
is absent. The problem has to do with what happens
when we create homes devoid of nearly all biodiversity except
that which falls from us, and then for twenty three
hours of the day we don't go outside. So they're
kind of getting high on our own supply here. Yeah,
I mean, that's that's exactly. I mean, it's we're in
(23:39):
these interior worlds. We're not we're actually going to great
pains and many times or just by the virtue of
the shape of our cities, in the shape of our lives,
we're not bringing anything in or we're ringing in as
little as as possible, and except for everything that just
sheds off of us. This kind of like constant um um,
you know, fog of detritus that we're leaving in our way. Now,
(24:00):
this isn't to say there aren't some really interesting things
living in the average human home. In his book, Done discusses,
for instance, the thermophilic bacteria Thermus aquaticus, which normally thrives
in hot springs and geyser's uh, you know, kind of
a you know, a specialist in that regard, but you
can pretty much rely on the fact that you can
(24:23):
find it in your hot water. Here a part of
your artificial environment that recreates environmental conditions that it finds favorable. Yeah.
Anthes discusses the research on shower heads. Apparently there tends
to be a lot of bacteria living in biofilms. And
biofilms are you know, these mats that microbes make when
(24:45):
they gather in big concentrations. For example, the dental plaque
on your teeth is a biofilm. These tend to form
on shower heads in our showers. We don't know exactly why,
but maybe because you know, hey, it's the shower, doesn't
it just get mean by itself, Like do I really
need to clean it? Uh? It is clean, it's water
coming out of it, exactly. It's kind of the logic
(25:08):
that's like, why would I ever need to wash my
bath towels? You know, they only touch me when I'm
at my cleanest um. But Anthus quotes Noah Noah Fear,
explaining that when hot water suddenly starts shooting out of
the shower head where these films are perched, it creates
this kind of mist and spray that carries bacteria with it,
(25:31):
and then of course, standing there under the spray in
the shower. We ingest that spray, we breathe it right in,
and Fierra says, quote, I think it's a really important
mechanism by which we're exposed to bacteria. Which, okay, so
you might be thinking again like, oh my god, my
shower head, you're filled with horror, But it's not necessarily
a bad thing. Again, like a lot of our exposure
(25:53):
to microbes is either neutral or beneficial, though of course
not all of it. Yeah, yeah, the bio films in
your shower head contained mostly harmless bacteria, but it but it.
Interestingly enough, it includes non tuberculosis uh micro bacteria, which
are relatives of leprosy and tuberculosis. Um. The interesting thing
(26:13):
here is that their chlorine tolerant. So while the chlorine
in a like a major metropolitan water system kills a
lot of the micro organisms that it might otherwise be
found there, it doesn't hurt these guys and actually creates
room for them to grow and to thrive. So they
are otherwise quite rare, and say, well water, uh, these
(26:34):
are I think I read that these biofilms are typically
found in general, are found in swamps totally adapted to
altering between wet and dry conditions much like your shower head. Um.
But yeah, in the natural world, they're just gonna have
their their niche to occupy. But we've created an artificial
environment where they have room to just really grow and
(26:56):
thrive and then of course rain down upon us, and
there could be health and cations about those microbacterial films.
We don't know for sure, but there's a there's a
possibility Anthes talks about. She writes, quote in fact, Fire
and Donne discovered that showerheads harboring potentially dangerous strains of
microbacteria clustered in the same regions mentioning Hawaii, southern California,
(27:18):
Florida in the mid Atlantic that are known to be
hot spots for microbacterial related respiratory infections. So the question
is are people getting these infections from their shower heads
of Fiarre suspects that might be the case, but that
doesn't necessarily mean your shower head is making you six.
Some microbacteria, when inhaled, are are not harmful. They might
(27:41):
even strengthen your immune system. Now Done points out that
that we've been studying microbiota in our homes actually since
the earliest days of microbiology. Uh, you have. This individual
by the name of Anthony van Lewenhoek who lived sixteen
thirty two through seventeen twenty three, and he's often called
is the father of microbiology and and weirdly enough, he's
(28:04):
possibly the model for two different Vermeer paintings. I don't
know if you've read about this. Yeah, um, well, I
encouraged listeners to look it up. It's pretty fascinating. Like,
basically he knew Vermier and may have posed for these paintings.
But he's the first individual known to have engaged in
this sort of study. He charted the microbial populations of
his own house, of his own body, and also some
(28:26):
neighbors homes and bodies. Um with permission I believe. But
but after his death, no one really bothered with the
sort of study again until we realized later that some
of the microbes we encountered could make us sick. And
so it's really it's it's really getting into modern times
here where we're finally, uh, taking a close look at
(28:47):
our household microbial environment with researchers like done playing a
key role. Um. Here's another great quote where he's just
talking about, you know, undertaking this this project and what
they expected to find. He says, quote, we expected to
find hundreds of species. Instead we discovered depending on just
how you do the math, upward of two hundred thousand species.
(29:09):
Many of these species are microscopic, but others are larger
and yet nonetheless overlooked. Breathe in inhale deeply. With each breath,
you bring in oxygen deep into the alveoli of your lungs,
along with hundreds or thousands of species. Sit down. Each
place you sit, you are surrounded by a floating, a leaping,
crawling circus of thousands of species. We are never home alone.
(29:33):
And this is on top of tins and perhaps hundreds
of different types of vertebrates, as well as various plants.
And then there are the arthropods and the fun guys.
Something like forty thousand species of fungi that can be
found in the home um. But the bacteria are just
really the crazy Party points out that more species of
bacteria have been found in human homes than there are
(29:54):
species of birds and mammals on Earth. Yeah. This type
of research is also explored in in ant this book,
where there's a section where she talks about how done
and fear followed up on their initial research from you know,
asking people to take the swabs from the different parts
of their home to find out what was there. They
decided to do like a bigger, deeper study of the
(30:14):
microbes found specifically along the trim of interior doorways. And
they picked this area because nobody ever cleans it, so dust,
you know, collects for years maybe without being sterilized, and
this would give you potentially a fuller inventory. And they
just found enormous numbers of bacteria. In anthesis book, the
(30:37):
number is over a hundred and sixteen thousand species of bacteria,
more than sixty three thousand species of fungi. And the
count of fungi species was especially interesting to them because
they found more numbers of species of fungi in these
samples around doorway trims than there are named species of
fungi in all of North America. So it means that
(31:02):
inside our houses, it's it's very likely that there are
species of fungus that have not yet been discovered or
cataloged by science. And they also found that that for
some of these samples, there was more uh fungi diversity
inside the house than outside the house, which interest which
(31:23):
reminds me of the scene in Primer where they don't
realize they've created a time machine yet and they think
that that the box that they put together as an
incubator for mold. Oh I forgot about that detail that
a while since have seen that one. And fungi in
our homes are somewhat different than bacteria in our homes,
so that they have a different, different vectors in different
ways of living. Anthests discusses how the bacteria in our
(31:46):
houses they mostly come from us and from the other
creatures that live with us, like dogs, and we'll get
into more on that in a bit, but the fun
guy are not as populous on and in our own bodies.
They tend to come more from the environment outside. And
what kind of fungi are found within a home is
largely determined by where the home is regionally, in the
(32:08):
climate around the home, what kind of fungi are prevalent
in the exterior environment. But there are other factors that
have an effect as well. And there's one that I
found very interesting. It was what the house is made of,
And she quotes from done saying it's kind of a
three pigs thing. A stone house feeds different fungi from
a woodhouse from a mud house, because unlike the bacteria,
(32:31):
they're eating the house. So it's like, what have you
put out on the buffet for them? Yeah, I mean again,
it comes down to the fact that our home is
not this um, this alien thing, you know, it is
made out of the natural world, and therefore there are
things that want to eat it. They eat those materials
that made up your home. Uh So, yeah, it's it's
(32:53):
easy to overlook that. But yeah, it makes perfect sense.
So obviously, I'm sure some people despite our our warnings
early on or like, okay, I'm just getting the bleach.
I'm gonna sterilize my entire living space. Maybe now we
should explain why that that might not be a good idea. Yeah,
that that might be your inclination. And and really it
kind of falls in line with what advertising has has
(33:16):
been has been telling us for years, you know, the
sort of world that we grew up in, where it's
like we got to disinfect the house, you gotta keep
the house clean, as if there is this absolute cleanliness,
this nobiotic um aspect of our homes. But but this
way of thinking is essentially treats our homes again like
some sort of lifeless, nobiotic box, hermetically sealed from the outside,
(33:38):
an impervious to occupation by anything but the presumably nobiotic
creatures living inside it. But all of this, you know,
nothing could be further from the truth, because nature of
horrors of vacuum and your home will come to harbor
a robust ecosystem. But our actions and our choices have
an effect on that ecosystem, as we saw with the
(33:59):
showerhead in the and the water heater or example above.
You may keep certain things out, but that just means
there's more room for other things to make themselves at home.
All right, Well, we need to take a second break,
but we will be right back with more than thank
thank Alright, we're back. So raining anti microbial death down
on your apartment or house is is also crazy, given that,
(34:22):
as Done and Sebastian Tilt discussed in a two thousand
nineteen study published in Nature Ecology and Evolution, only a
relatively small proportion of the micro organisms in our environment
actually cause disease. It's also worth noting that insects and
other arthur pods, especially spiders that live in in the home,
are important actors in the ecosystem, as they can exterminate mosquitoes, bedbugs, cockroaches,
(34:49):
and house flies, all of which actually can transmit diseases.
And it's not a universal thing around the world that
people see a spider in their house and say, oh,
we've got to kill that. Like some cultures are much
more taller rent of spiders with the knowledge that they're
performing this important cleaning service. Yeah, I personally like seeing
the spider in the bathroom every day. You know it's
(35:10):
it's a friend. You know that it's it's he or
she is working to to to help make this bathroom
a better environment. In that paper by Done and Tilt Uh,
the authors agree that there there's simply no need to
weigh devastating war against all of these organisms, but more
to the point, a lot more work is needed to
determine just what sorts of environments are more susceptible to
(35:31):
the bad stuff. Another interesting wrinkle in all of this
is that and and this is one Done discusses in
his book, is exactly what household dogs reveal about the
contrast between the exterior ecosystem and our interior worlds. Dogs
are amazing at bringing you filth that I think about
(35:51):
this with my dog every day. It's like every single
day he's like, let me nourish your microbiome. Well, I
think ultimately the way to look at it is the
dog is not just bringing filth in. The dog is
nurturing your filth. Like there's going to be filth if
you wish to categorize the microbial world as filth. Uh,
there's no escaping it. Um. So the dog is ultimately
(36:13):
just bringing something to the equation. So for a lot
of us, we tend to leave our our artificial interial world,
you know again, hop into another one that happens to
have wheels, travel, does to work, come back, etcetera. A
lot of us do get out into the natural world,
but there are plenty of us that don't do it
on a regular basis. If you have pets, indoor only
(36:33):
varieties contribute to the microbial stew that is your home.
But there's no beating a dog for a bridge between
inner and outer ecosystems. There's also no beating a dog
just in general. I don't want to encourage anybody, but
for starters, your dog is likely drawing you out into
the outside environment. Uh, you know, you're gonna probably hopefully
(36:54):
you're gonna take your dog on walks, You're gonna, you know,
go out into the world with it. But at the
very lead, that dog is going out to get all
up in the natural world and then bring some of
it back home. This, this has been your experience with
his a dog owner. Correct. Now, Now, there's certainly harmful
possibilities here, such as if your dog were to bring
back fleas or ticks, and this has always been an
(37:16):
issue with ancient Egyptian dog remains showing signs of brown
dog ticks, which certainly do carry pathogens. But there's also
a plethora of harmless effects and a seemingly beneficial um
impact as well. Done points out that by looking at
household microbes alone, first of all, one can tell if
there's a dog in the house at all of the time.
(37:40):
The dog just leaves a microbial footprint that's hard to
mess But beyond this, it's hard to tell at this
point what specific effects dogs and cats have on the
inner and microbial environment, because there's a lot of complexity there.
But Done says that we certainly see, especially in urban
environments with dogs, that the children in those households are
(38:01):
less prone to allergy and asthma. So the dogs might
actually be a vehicle connecting the children to nature, and
just the dirt on their paws, for instance, might be
enough uh to essentially provide some sort of uh replacement
for spending time in nature and in the natural microbial environment. Yeah.
(38:23):
This is the connection to what used to be known
as the hygiene hypothesis, though Anthesy notes that some researchers
have pointed out that this name can be kind of
misleading because the point of the hygiene hypothesis is not
that you like, shouldn't wash your hands. Uh. It's more
about having an exposure to a diverse array of microbiota
(38:44):
early in life can, if this hypothesis is correct, help
help strengthen your immune system in various ways and make
you less prone to say, allergies and asthma and things
like that. More recently, people have tried to to recoin
this thing not as the hygiene hypothesis but as the
old friends hypothesis, Like the the natural microbial world is
an old friend that we should reacquaint ourselves with, and
(39:08):
that it's good to get acquainted with early in life. Uh,
not necessarily that you like shouldn't wash your hands or
shouldn't wipe down the counter after you've been slicing chicken
or something. Yeah, now this is primarily with dogs. With
with cats, there seems to be far less of a connection. Uh.
And also it's noted that in rural environments, uh, we
see less evidence of this and the ideas that individuals
(39:29):
in a rural environment are probably getting more exposure to
to the outside of the natural world in general, so
the dog isn't going to make that much of a difference.
The dog is less of a tap of hot and
cold running exterior microbes. And I think all of that
helps to underline, you know, our desire and our inn indeed,
our need to get out of the house and interact
with nature on a regular basis. Uh. Dunn says that
(39:53):
that one day we might be able to manage our
interior microbiota in a way that will help ensure that
we're healthy and uh and that you know, everything's in balance.
But for now that's just not the case. We just
we don't understand and enough of we haven't explored, uh,
the the interior world enough to know exactly what we're
dealing with. And again, like what kind of environments are
(40:14):
are more prone to be occupied by the bad stuff
versus the the the beneficial stuff, or the stuff that
is just uh there and part of the world we
live in. Though, I think it is clear that built
environments do make a difference. Uh that we we don't
fully understand exactly what all the causal relationships are yet,
but there have definitely been measured differences that show, for example,
(40:34):
where rooms are placed and what their relationships to other
rooms where different things happen, uh, that that does affect
what kinds of microbiota we find in those rooms. Just
the example of having open windows that open to the
outside world as opposed to having a room that's all
closed off to the outside world and just ventilated by
(40:55):
you know, HVAC systems. That makes a difference to what
the microbiome of the room look like. Yeah, I mean,
I mean even if the windows don't open. You know,
we've looked at studies before, they've looked on the psychological
impact of just being able to see the outside world,
especially in hospital environment. Uh. And we do know a
few other things too, Like one of the things that
(41:15):
ant this mentions it seems to be a pretty straightforward
finding is that one good way to encourage healthy ecosystems
of microbes within the house is basically to keep the
house dry. Moisture seems to activate a lot of unwanted
fungal activity, but you can still have a lot of
healthy microbes with the house that's that's relatively dry. Uh.
You know that. She says that a lot of these
(41:37):
experts who are looking at this do not recommend using
anti microbial agents in the house, as you've been talking about.
So there are a few things we know, but yeah,
there's still a whole lot more to learn about the
interactions between our our living space architecture and our home
cleaning regimes and all that stuff with the microscopic invisible world. Yeah,
(41:58):
and it's interesting. I mean, obviously it's gonna be more
of a challenge and damper environments, say like, um, you know,
a rainforest environment. But I guess there, I guess one
is tempted to to ask the question, well, what are
the traditional modes of housing? You know, what were the
were the were the trial and error developments in housing
there versus the um that the modern solutions that have
(42:21):
been brought in from other environments without perhaps without really
taking full account of the local conditions. Yeah, that's an
interesting question. I haven't considered that. Yeah, I mean, I
don't know. You walk around any given neighborhood, right and
you you you see these trends and homes and occasionally
you'll see a home that is that it's clearly out
(42:41):
of place. But it makes you wonder, like, just how
out of place is it? Is? The design like not
suited for the you know, the energy consumption rates or
the or or just the like the the level of
the amount of sun you get in a given part
of the world, that sort of thing. Uh, you know,
I think one of the things we can take from
this episode is that homes are are far more complicated.
(43:04):
They're not just the the space we in which we live,
you know, a container for our lives. Like they they're
gonna shape who we are on a microbial level, on
a symbolic level, Um, it's uh, you know, it's it's
it's mind blowing stuff, definitely. And then sometimes you find yourself,
you know, during a pandemic, spending a lot of time
(43:27):
in your closet recording podcasts in your laundry room. Yeah,
rooms that were never designed or intended for this kind
of lengthy habitation. Luckily, my my closet here does have
an air event in it um, which has been a lifesaver.
I don't think my laundry room does around for it.
(43:47):
I have I've had a few sweaty times in here. Well,
it's this good news for when the winter sets in,
right for both of us, because I think this is
gonna be pretty cozy in here. And if you get
cold in the laundry room, you can always just turn
on the dryer. I'm really trying to get it's set
up so that I can record from a different room.
I'm trying to to make a different room in the
house less echoy, so I can get good sound and
(44:08):
not have to hunch over next to the washing machine.
I am digging an earthen pit in my backyard, which
I am told will have a really good uh sound installation.
So we'll see how that goes. Mammoth Bones Studio. Yes,
all right, Well, there you have it. Hopefully this provides
some some food for thought. Again, we're not trying to
encourage anybody to go on a any kind of a
(44:33):
killing spree in their house concerning microbes or Arthur pods
or anything like that. Uh, just we thought that as
we're spending more time looking at our homes and thinking
about getting out of nature, we should really look at
what the in the relationship between those two environments actually is.
In the meantime, if you like to check out other
episodes of Stuff to Blow Your Mind, well you can
(44:55):
find us wherever you get your podcast and wherever that
happens to be. Just make sure you rate your you
and subscribe and if you get in touch with us,
I mean clearly we'd love to hear your thoughts on
this episode. How do you relate to the content here?
How does it change or back up your own thoughts
and observations concerning your interior environment or the external world?
(45:17):
Hughes thanks as always to our excellent audio producer Seth
Nicholas Johnson. If you would like to get in touch
with us with feedback on this episode or any other,
to suggest a topic for the future, just to say hi,
you can email us at contact at stuff to Blow
your Mind dot com. Stuff to Blow Your Mind is
(45:40):
production of I Heart Radio. For more podcasts for My
Heart Radio, visit the iHeart Radio app, Apple Podcasts, or
wherever you're listening to your favorite shows proper posts, stars
(46:04):
b
Welcome to Stuff to Blow Your Mind production of My
Heart Radio. Hey you welcome to Stuff to Blow your Mind.
My name is Robert Lamb and I'm Joe McCormick. And
today we're gonna be taking a look at interior spaces. Yeah,
the year certainly brings to mind the old curse, May
(00:23):
you live in interesting times? And one of the factors
here has of course been the coronavirus COVID nineteen pandemic,
and in an effort to fight the spread of the illness,
save lives, and prevent overwhelming our hospitals, we've made a
lot of changes to our lives and these range from
the simple such as just wearing a mask when you're
out in public and you can't social distance from people,
(00:45):
to the harder choices about employment and uh in life choices,
we've all been social distancing and stay at home orders,
teleworking and quarantine have meant that we've all been spending
a lot more time at home now. Depending on your home,
this could mean a lot of things, but we wanted
to explore what this means from a biological standpoint for
(01:07):
the most part here now now, make no mistakes, spending
more time at home has absolutely been the right move.
But just as it's forced you to focus more on,
say that weird staying on your ceiling, we wanted to
focus on the other, often unseen aspects of life in
the home right much the same way that being say
on a Spanish galleon out in the middle of the
(01:27):
ocean might have made you pay much more attention to
the biology and behavior of of ship rats than you
ever would have otherwise. I think being at home more
and more is forcing all of us to turn our
eyes and maybe our microscopes and magnifying glasses to the
corners and the cornices, and the shower heads and the
drain traps and all of the wonderful places in our
(01:49):
house where life dwells. Yeah, we're gonna really get into
the difference really between the natural world outside of our
homes and the unnatural world inside, and get into some
ideas about how how we could perhaps enable our interior
world to be a little more on the natural side
of things. But before we get into all that, I
(02:11):
wanted to take a moment here just to discuss the
history of houses in general, you know, just to get
into the concept of what a house is. Our our
first and still most important interior artificial environment. So you
can certainly look at a home as an artificial cave
to a certain extent. And indeed, we have lots of
(02:31):
early evidence that early hominids sought out shelter in caves
in the same way that many other animals do. UH.
These can shelter one against the elements and against predators,
And as recently as a hundred and thirty thousand years ago,
cave dwellers were already augmenting these natural interior environments with
things like rough stone walls. They were using timbers so um.
(02:55):
So you know, even a hundred thirty thousand years ago,
we were taking naturally occurring interior space paces and making
them a little less natural. Um. And of course, on
top of just the shelter that caves can provide, it
also seems that caves had a strong sacred meaning to
many of these UH prehistoric peoples. Those might be important,
but ultimately proximity to water is far more important. Thus,
(03:19):
as Kate Spence and Brian M. Fagan point out in
UH in the section of the seventy Grade Inventions of
the Ancient World about homes, most early hominids lived out
in the open near streams and lakes, they built temporary structures,
and most of this has been lost to time, but
some of the earliest evidence of potential structures for homes
(03:39):
goes back one point seven two point seven million years
ago with Homo erectus sites in southern Africa, and these
were potentially contemporary with the domestication of fire um and
these would have been temporary tents, but but they still
would have been artificial interior environments. Now more secure evidence
(03:59):
come from the Ukraine roughly forty four thousand years ago,
the mammoth bone structures from Maladova, which we recently discussed
on the show. Actually, yeah, we did uh talking about
these uh. That would have been structures in one of
the northernmost habitable regions of the Earth at the time,
because this was during a time of glacial advance where
(04:21):
the polar ice caps from the north were coming deep
down into Europe and Asia and uh and so this
would have been far far north, way up among the
ice and for some reason humans were building these structures
out of the bones of mammoth and we don't know that.
There's still things we don't know about those structures, like
how how consistently they were inhabited and for how long
(04:42):
and so forth. Right Now, beyond this, the history of
human homes is is largely dictated by local resources and
a local climate. A long process of trial and air
ends up leading to the development of regional and cultural
building forms construction methods. But before nine tho see we
see evidence of clay houses in Palestine and what is
(05:03):
today Palestine, and before seven thousand b C. We see
rectangular dwellings in Anatolia. But but at home is far
more than just a shelter. As the authors here point out,
houses became key to social structure as well. They point
out that the ethnographic studies in West Africa reveal complex
(05:23):
and layered symbolic associations and rituals in the context of dwelling,
and that this is it shows that a clear role
of physically structuring and expressing the relationship between different members
of the household. And we see this of course in
um and cultures. You know, throughout history and throughout the world.
There's this physical shape of the place, uh, and then
(05:47):
that ends up defining or influencing like that, there's this
this feedback between the two. It goes both ways. Right,
it's kind of like pouring a liquid into a container. Oh,
of course. And this actually got me thinking about how
having permanent, constructed dwellings must have changed the way that
power and hierarchy are expressed in social groups. And of
course this is true with normal social status. You know,
(06:10):
it's it's staked out through displays of wealth. There certain
kinds of taste or aesthetics in your house, your apartment,
your you know, your living space. But this also made
me think about the way that for many leadership positions,
there is a special house, there's a special dwelling place
that comes with the job, rather than belonging to an individual.
So here in Georgia we have the governor's mansion. There
(06:33):
is the White House there, you know, the palace that
the king stays at in many cultures, and there's a
there's a strange metonomy that derives from this. Often the
house identified with the position of power is used as
a metaphorical stand in for the person, you know, like
today the white House said such that, like, the permanent
(06:53):
dwelling place is actually almost the source of the power,
and there just happens to be a particular person living
there right now. Yeah, it's weird. We get so used
to it because it's just part of our daily um,
you know, our daily you know linguistic world. You know,
you can read the news, you read about these various locations,
these houses, and it's almost as if they have some
(07:15):
sort of intrinsic power to them, right, I mean, if
you weren't familiar with their cultures, you would read this
then and people might think, oh, well, they they clearly
thought that this big, white um house had some sort
of magical powers and whoever was allowed to go inside
it became the ruler of a country and got to
do whatever they want. Yeah, And it's funny that it's
so normalized for us, like we've forgotten to notice that
(07:37):
that's weird that like the power is somehow linked to
the house itself. Um. But it also makes me wonder,
you know, did we think about power differently before living
in artificially built environments? Yeah? To what extent did we? Um?
Did we end up yet changing the way we live
our lives by altering this physical environment which we live?
(07:58):
I mean it makes sense, right, because so much of
what we do, you know, it's dictated by the environments
that we evolve to thrive in right. So anyway, I
don't think we need to remind everyone about the value
of a home. Housing tends to be one of, if
not the most expensive parts of your life, but it's
it's interesting to think about them not simply as this
valuable thing in your life, for a valuable location where
(08:20):
your life takes place. The basic idea of the house
may be as old as our mastery of fire, and
it forms out of and forms ideas of who and
what we are, and of course it may do so
in more and more powerful ways every year, as humanity
slowly transitions to become a more indoors e on average species.
(08:41):
All the time, I was reading some interesting figures about
this trend in a book by the science writer Emily
and This uh in the book is called The Great
Indoors The Surprising Science of How Buildings shape our behavior, health,
and happiness. This is a really interesting book and I'm
going to refer to it throughout this episode because she
has an early chapter that's very good about the microbial
(09:03):
ecology of indoor spaces. But she also gets into some
interesting territory about the trends in how much built environment
and floor space we're actually creating. Obviously, this currently varies
a lot by culture and climate, but in some parts
of the world human kind is transitioned to an almost
entirely indoor existence. And this really shows in the way
(09:26):
we've transformed our environments to convert to this largely indoor existence.
Uh Anthes writes, quote, the island of Manhattan is only
twenty three square miles in size, but has three times
that much indoor floor space. And furthermore, she refers to
a report put together by a United Nations commission in
(09:47):
which concluded that over the next forty years, humankind is
going to roughly double the amount of indoor floor space
that exists currently. And the way this works out is
quote those additions are equivalent to building the current floor
area of Japan every single year from now until Wow.
(10:08):
That much floor is going to take a lot of
pine sawl Yeah. I mean it is crazy to think
about how certainly during pre pandemic times, you know, you
would you had this home, this interior space that you
live in, you sleep in, you bathe in, you spend
time in, and then uh and it is you know,
very much like the center of your life. And then
(10:31):
you're getting into another interior space, which happens to be
motorized and on wheels, and use that to travel then
a certain distance to another interior space that you'll go
into to work, either set at a desk or you know,
work with some sort of machinery or what have you. Uh,
and then at the end of the day back into
(10:51):
this uh, motorized interior space and then return to the
one in which you live. It's worth remembering yet again,
biologically speaking, this is not normal. This is not like
what our bodies are naturally adapted to. Spending this much
time indoors is still fairly historically novel, and it is
very weird. Yes. But the other big thing, and this
(11:13):
is going to be a recurring theme throughout the rest
of the episode, is that these artificial spaces that we made,
they are they're not completely alien, you know, they're they're
constructed all of the natural world. They're not the natural environment,
but they are made out of it. And uh and
and much of the natural world is still present, just
(11:35):
in um rebalanced and unbalanced ways. Uh. So that that
is going to be what we're going to really get into, Like,
what in creating these interior spaces, what sort of environments
have we created? Right, Indoor spaces are not unnatural in
that they're completely separate from the rest of the world,
but they're also not just like outdoor spaces. They're kind
(11:57):
of like a special niche environment, like a like a
cliff face or an island. You know, it's a place
where you have to investigate. Okay, what kinds of life
from around and other places are going to colonize this space? Yeah?
And and who are your roommates? Who are your inhuman
roommates in this space where you've been trapped? Uh these
(12:18):
past several months. Well, maybe we should take a break
and then when we come back, we can start talking
about those in human roommates. All right, we're back, so uh.
Rob Donne, a professor of applied ecology at North Carolina
State University and Raleigh, wrote an excellent book titled Never
Home Alone. From Microbes to Millipedes, camel, crickets and honey bees,
(12:43):
then Natural History of Where We Live. That's a nice
long title. I know you'd be like those those long
coland titles, want like a whole paragraph after the colon,
but it's it's it's hard as they go. It's pretty
good title. Anyway, it came out last October and it's
currently available in all format. So however, you read your books.
But I remember hearing an interview with the author around
(13:04):
the time that came out, and I picked it up
for this episode because it's, yeah, it's it's it's just
a very well written book and it really gets into
some just crazy, uh mind bending facts about these artificial environments,
most of which we won't even really be able to
get into in this episode, but we wanted to touch
on it. So if you look around its science papers,
you'll find Dunn's name um all over the place when
(13:27):
it comes to this area of microbial life. For instance,
he's the co author on a two thousand eighteen paper
that found that chimpanzee tree top beds, which are like
a daily affair, contained fewer microbes and Arthur pods than
human beds, which is not shocking given again the the
idea that ore beds that are kind of like set
(13:48):
in place, Um, you know, we will change the sheets,
but it's not every night probably, whereas the chimps are
going to be refreshing things a bit more. Also, thirty
of the bacteria in human beds stem from our own
bodies and includes fecal, oral, and skin bacteria. Yeah. The
way I heard it put, because this is covered in
Anthesis book too, is that with the with the human bed,
(14:11):
basically you're just gonna find tons of human type stuff
in it. But for a chimpanzees bed, you will find
you know, bugs, arthur pods, and microbes in in this bed,
but they're almost all from the surrounding environment. Uh. The
way it was put was that you might not be
able to tell that a chimpanzee had ever been there. Right,
very strange. But from Anthesis book there's uh So there's
(14:35):
a chapter that discusses a lot of the work of
the same researcher, robbed On, the the ecologist at North
Carolina State, but also a researcher that he's collaborated with
a lot named Noah Fierre, who's a microbiologist at u C. Boulder,
And there's a part where it talks about a survey
that they tried to conduct called the Wildlife of Our
Homes Project. There was a pilot study they started in
(14:57):
North Carolina, and so they would do was they would
get a bunch of families to take cotton swab samples
of seven different surfaces from inside their homes, and this
would include a countertop, a cutting board, a refrigerator shelf,
a pillow case, a toilet seat, a TV screen, and
then the trim around an interior doorway. And the results
(15:20):
were interesting. They found more than two thousand types of
microbes in these samples, and there were distinct microbial habitats
within the house. So perhaps on surprisingly, kitchens would have
a lot of bacteria that are naturally associated with food
that might be you know, found on food or aid
in the decomposition of food. Meanwhile, doorways would have a
(15:42):
lot of environmental species stuff you might find outside the house,
you know, things you would find on plant leaves and
in the soil. But then this was the quote that
really stuck with me, And this writes quote from a
microbiological perspective, toilet seats and pillow cases looked strikingly similar.
But we're dominated by bacteria that typically live on our
(16:03):
skin and in our mouths. All right, So that's that's
kind of a shocking sounding statement that might make you
want to instantly go and wash your pillowcase and maybe
your toilet seat too. But but but hold on, wait
till we get through the whole episode, because I think
one of the big tacomes here is like, if you
think that your pillow is going to be a microbial
(16:23):
sterile um experience, you know you should think again, likewise
with the toilet seat, likewise with anything in the house.
So in Dunn's book, one of one of the things
he drives home is that again our our house environments
are again not natural environments, but they are made out
of the natural environment, and they are not cut off
from the natural environment. So what we end up with
(16:44):
is an artificial environment that kind of mashes up all
of these various environmental parameters, sometimes in surprising ways, especially
when it comes to microbes, because if we as we've
discussed on the show plenty of times before, there is
no microbe free living our bodies, independent of anything else,
our home to multitudes of microbes. To come back to
a quote that we've pulled up on the show in
(17:06):
discussion in the past. In a Life in a World
without Microbes by Gilbert and Newfeld published in PRST Biology,
the authors contend that quote it would be false to
claim that macroscopic life cannot exist without microbes. However, although
life would persist in the absence of microbes, both the
quantity and quality of life would be reduced drastically. So
(17:27):
Done points out that even the outer layer of our
skin is just this rich microbial environment. Our armpit bacteria
are essentially fed by glands nurturing what has likely been
an historically important microbe passenger. And we can we can
look at this as an example of the sort of
microbe that then thrives in our creative environments. We tend
(17:48):
to find the same bacteria uh that that that thrives
in our under arms living in our homes, especially homes
where males live. If there's like a predominantly male population
of a house sold, you will find this particular bacterium.
I believe it's uh corn a bacterium just thriving Coarina bacterium,
Coarina bacterium. Yes. Yeah, So this thing about the sex
(18:11):
composition of the household versus the household microbiome was also
mentioned in anthesis book, and it's very interesting. So just
as you say, homes with more male residents tend to
have higher counts of bacteria such as Rosa burria and
this is commonly a gut bacteria, as well as Karina
bacterium and Derma bacter and uh at this points out
(18:34):
that these are most common on the skin. Now, Coarina
bacterium is often found in the armpit. As you say,
it is a contributor to body odor. But also it's
been found that just on average, men tend to have
more Coarina bacteria on their skin than women do, and
men tend to shed more skin microbes into the environment
than women do. And then on the other hand, households
(18:56):
that have more women living in them tend to have
higher counts of Lactobacillus, which is our old friend from
the fermentation episode. I don't know if this translates to
a workable difference, maybe not, but it makes me wonder
if it's possible that houses occupied by higher numbers of
women might be a better place to make sauerkraut. Interesting,
just some to think about, but sort of. What this
(19:18):
suggests is that humans are walking fountains of microbes. We
we shed our microbial passengers everywhere we go, and it
turns out this can be kind of quantified to creepy levels.
So consider this. No two people's microbiomes are exactly the same.
Each person is a unique ecosystem. So if everybody has
(19:41):
their own unique profile of microbiota, and everybody is shedding
microbial life all the time, are we essentially leaving identifiable
microbial evidence of our presence everywhere we go, you know,
kind of the slug trail of our microbiome all over
the place. And the answer appears to be kind of yeah.
(20:01):
At this reports one study led by Jack Gilbert at
the University of Chicago. I think that might be the
Gilbert of the Gilbert and Neufeld study that you mentioned
a minute ago. But it followed three families that were
in the process of moving into new homes. And what
Gilbert and colleagues found was that each family began to
(20:21):
colonize the new house with their microbes within just hours
of arriving there. Uh. And that the researchers quote could
even detect the individual microbial contributions of each family member. Uh.
And then Gilbert says, people who spent more time in
the kitchen, their microbiome dominated that space. People who spent
(20:42):
more time in the bedroom, their microbiome dominated there. You
could start to forensically identify their movement. Oh wow, So
this this makes one try to imagine like law and
order microbiology, yes, surveillance biotech. Yeah. But to come back
to to Rob Dunn's example about Corina bacteria in homes,
(21:06):
especially where males live. You you had an interesting thing
about that, Yeah, because he brings up a very curious
case of of an interior environment in interier home that
had a predominantly certainly at the time of the study,
had a predominantly male um population, and that is the
International Space Station. So this was basically there was a
(21:29):
study of the micro buyouta one finds inside the I
S S. This was conducted in two thousand thirteen by
Jonathan Ien, a microbiologist at u C. Davis. So, the
the I S S done rights, is very much like
a house on Earth. Quote, in nearly every way, the
bacteria of the I S S are the sorts of
(21:49):
bacteria we would expect in a house on Earth if
all the environmental influences were removed. I S S is
what you get when you scrub and scrub and close
the windows, doors and hatches. So the I S S
might be kind of like a very well scrub department
in a high rise in a big city. Yeah, I mean,
there's there's no outside to get inside, right, Um, I
(22:11):
mean immediately so obviously, um, stuff can be brought up,
but anyway, done also points out that in this study
of iss microbes, quote, everything was everywhere. The interior was
just codd in human bacteria, and nothing from outside was
getting in. Obviously. He points out that in a small
traditional home made out of mud and leaves, which would
(22:34):
have been you know, the normal for the vast uh,
you know, the vast majority of human existence, everything would
be everywhere as well, but environmental microbes would be everywhere.
What's outside would be inside. But for the I s
s there there is no outside. Really, it is a
you know, this sterile environment that is then inhabited by
human beings certainly, but then inhabited populated by human microbes.
(22:57):
So so environmentally sterile, but heavily colonized by what the
humans bring with them, right, He writes, quote, if you
scrub and scrub your home, this is what you may
achieve too. It is not unlike what we see in
some apartments in Manhattan, And as we and others have
begun to study such apartments, we have found a problem.
(23:17):
The problem is not what is present, but instead what
is absent. The problem has to do with what happens
when we create homes devoid of nearly all biodiversity except
that which falls from us, and then for twenty three
hours of the day we don't go outside. So they're
kind of getting high on our own supply here. Yeah,
I mean, that's that's exactly. I mean, it's we're in
(23:39):
these interior worlds. We're not we're actually going to great
pains and many times or just by the virtue of
the shape of our cities, in the shape of our lives,
we're not bringing anything in or we're ringing in as
little as as possible, and except for everything that just
sheds off of us. This kind of like constant um um,
you know, fog of detritus that we're leaving in our way. Now,
(24:00):
this isn't to say there aren't some really interesting things
living in the average human home. In his book, Done discusses,
for instance, the thermophilic bacteria Thermus aquaticus, which normally thrives
in hot springs and geyser's uh, you know, kind of
a you know, a specialist in that regard, but you
can pretty much rely on the fact that you can
(24:23):
find it in your hot water. Here a part of
your artificial environment that recreates environmental conditions that it finds favorable. Yeah.
Anthes discusses the research on shower heads. Apparently there tends
to be a lot of bacteria living in biofilms. And
biofilms are you know, these mats that microbes make when
(24:45):
they gather in big concentrations. For example, the dental plaque
on your teeth is a biofilm. These tend to form
on shower heads in our showers. We don't know exactly why,
but maybe because you know, hey, it's the shower, doesn't
it just get mean by itself, Like do I really
need to clean it? Uh? It is clean, it's water
coming out of it, exactly. It's kind of the logic
(25:08):
that's like, why would I ever need to wash my
bath towels? You know, they only touch me when I'm
at my cleanest um. But Anthus quotes Noah Noah Fear,
explaining that when hot water suddenly starts shooting out of
the shower head where these films are perched, it creates
this kind of mist and spray that carries bacteria with it,
(25:31):
and then of course, standing there under the spray in
the shower. We ingest that spray, we breathe it right in,
and Fierra says, quote, I think it's a really important
mechanism by which we're exposed to bacteria. Which, okay, so
you might be thinking again like, oh my god, my
shower head, you're filled with horror, But it's not necessarily
a bad thing. Again, like a lot of our exposure
(25:53):
to microbes is either neutral or beneficial, though of course
not all of it. Yeah, yeah, the bio films in
your shower head contained mostly harmless bacteria, but it but it.
Interestingly enough, it includes non tuberculosis uh micro bacteria, which
are relatives of leprosy and tuberculosis. Um. The interesting thing
(26:13):
here is that their chlorine tolerant. So while the chlorine
in a like a major metropolitan water system kills a
lot of the micro organisms that it might otherwise be
found there, it doesn't hurt these guys and actually creates
room for them to grow and to thrive. So they
are otherwise quite rare, and say, well water, uh, these
(26:34):
are I think I read that these biofilms are typically
found in general, are found in swamps totally adapted to
altering between wet and dry conditions much like your shower head. Um.
But yeah, in the natural world, they're just gonna have
their their niche to occupy. But we've created an artificial
environment where they have room to just really grow and
(26:56):
thrive and then of course rain down upon us, and
there could be health and cations about those microbacterial films.
We don't know for sure, but there's a there's a
possibility Anthes talks about. She writes, quote in fact, Fire
and Donne discovered that showerheads harboring potentially dangerous strains of
microbacteria clustered in the same regions mentioning Hawaii, southern California,
(27:18):
Florida in the mid Atlantic that are known to be
hot spots for microbacterial related respiratory infections. So the question
is are people getting these infections from their shower heads
of Fiarre suspects that might be the case, but that
doesn't necessarily mean your shower head is making you six.
Some microbacteria, when inhaled, are are not harmful. They might
(27:41):
even strengthen your immune system. Now Done points out that
that we've been studying microbiota in our homes actually since
the earliest days of microbiology. Uh, you have. This individual
by the name of Anthony van Lewenhoek who lived sixteen
thirty two through seventeen twenty three, and he's often called
is the father of microbiology and and weirdly enough, he's
(28:04):
possibly the model for two different Vermeer paintings. I don't
know if you've read about this. Yeah, um, well, I
encouraged listeners to look it up. It's pretty fascinating. Like,
basically he knew Vermier and may have posed for these paintings.
But he's the first individual known to have engaged in
this sort of study. He charted the microbial populations of
his own house, of his own body, and also some
(28:26):
neighbors homes and bodies. Um with permission I believe. But
but after his death, no one really bothered with the
sort of study again until we realized later that some
of the microbes we encountered could make us sick. And
so it's really it's it's really getting into modern times
here where we're finally, uh, taking a close look at
(28:47):
our household microbial environment with researchers like done playing a
key role. Um. Here's another great quote where he's just
talking about, you know, undertaking this this project and what
they expected to find. He says, quote, we expected to
find hundreds of species. Instead we discovered depending on just
how you do the math, upward of two hundred thousand species.
(29:09):
Many of these species are microscopic, but others are larger
and yet nonetheless overlooked. Breathe in inhale deeply. With each breath,
you bring in oxygen deep into the alveoli of your lungs,
along with hundreds or thousands of species. Sit down. Each
place you sit, you are surrounded by a floating, a leaping,
crawling circus of thousands of species. We are never home alone.
(29:33):
And this is on top of tins and perhaps hundreds
of different types of vertebrates, as well as various plants.
And then there are the arthropods and the fun guys.
Something like forty thousand species of fungi that can be
found in the home um. But the bacteria are just
really the crazy Party points out that more species of
bacteria have been found in human homes than there are
(29:54):
species of birds and mammals on Earth. Yeah. This type
of research is also explored in in ant this book,
where there's a section where she talks about how done
and fear followed up on their initial research from you know,
asking people to take the swabs from the different parts
of their home to find out what was there. They
decided to do like a bigger, deeper study of the
(30:14):
microbes found specifically along the trim of interior doorways. And
they picked this area because nobody ever cleans it, so dust,
you know, collects for years maybe without being sterilized, and
this would give you potentially a fuller inventory. And they
just found enormous numbers of bacteria. In anthesis book, the
(30:37):
number is over a hundred and sixteen thousand species of bacteria,
more than sixty three thousand species of fungi. And the
count of fungi species was especially interesting to them because
they found more numbers of species of fungi in these
samples around doorway trims than there are named species of
fungi in all of North America. So it means that
(31:02):
inside our houses, it's it's very likely that there are
species of fungus that have not yet been discovered or
cataloged by science. And they also found that that for
some of these samples, there was more uh fungi diversity
inside the house than outside the house, which interest which
(31:23):
reminds me of the scene in Primer where they don't
realize they've created a time machine yet and they think
that that the box that they put together as an
incubator for mold. Oh I forgot about that detail that
a while since have seen that one. And fungi in
our homes are somewhat different than bacteria in our homes,
so that they have a different, different vectors in different
ways of living. Anthests discusses how the bacteria in our
(31:46):
houses they mostly come from us and from the other
creatures that live with us, like dogs, and we'll get
into more on that in a bit, but the fun
guy are not as populous on and in our own bodies.
They tend to come more from the environment outside. And
what kind of fungi are found within a home is
largely determined by where the home is regionally, in the
(32:08):
climate around the home, what kind of fungi are prevalent
in the exterior environment. But there are other factors that
have an effect as well. And there's one that I
found very interesting. It was what the house is made of,
And she quotes from done saying it's kind of a
three pigs thing. A stone house feeds different fungi from
a woodhouse from a mud house, because unlike the bacteria,
(32:31):
they're eating the house. So it's like, what have you
put out on the buffet for them? Yeah, I mean again,
it comes down to the fact that our home is
not this um, this alien thing, you know, it is
made out of the natural world, and therefore there are
things that want to eat it. They eat those materials
that made up your home. Uh So, yeah, it's it's
(32:53):
easy to overlook that. But yeah, it makes perfect sense.
So obviously, I'm sure some people despite our our warnings
early on or like, okay, I'm just getting the bleach.
I'm gonna sterilize my entire living space. Maybe now we
should explain why that that might not be a good idea. Yeah,
that that might be your inclination. And and really it
kind of falls in line with what advertising has has
(33:16):
been has been telling us for years, you know, the
sort of world that we grew up in, where it's
like we got to disinfect the house, you gotta keep
the house clean, as if there is this absolute cleanliness,
this nobiotic um aspect of our homes. But but this
way of thinking is essentially treats our homes again like
some sort of lifeless, nobiotic box, hermetically sealed from the outside,
(33:38):
an impervious to occupation by anything but the presumably nobiotic
creatures living inside it. But all of this, you know,
nothing could be further from the truth, because nature of
horrors of vacuum and your home will come to harbor
a robust ecosystem. But our actions and our choices have
an effect on that ecosystem, as we saw with the
(33:59):
showerhead in the and the water heater or example above.
You may keep certain things out, but that just means
there's more room for other things to make themselves at home.
All right, Well, we need to take a second break,
but we will be right back with more than thank
thank Alright, we're back. So raining anti microbial death down
on your apartment or house is is also crazy, given that,
(34:22):
as Done and Sebastian Tilt discussed in a two thousand
nineteen study published in Nature Ecology and Evolution, only a
relatively small proportion of the micro organisms in our environment
actually cause disease. It's also worth noting that insects and
other arthur pods, especially spiders that live in in the home,
are important actors in the ecosystem, as they can exterminate mosquitoes, bedbugs, cockroaches,
(34:49):
and house flies, all of which actually can transmit diseases.
And it's not a universal thing around the world that
people see a spider in their house and say, oh,
we've got to kill that. Like some cultures are much
more taller rent of spiders with the knowledge that they're
performing this important cleaning service. Yeah, I personally like seeing
the spider in the bathroom every day. You know it's
(35:10):
it's a friend. You know that it's it's he or
she is working to to to help make this bathroom
a better environment. In that paper by Done and Tilt Uh,
the authors agree that there there's simply no need to
weigh devastating war against all of these organisms, but more
to the point, a lot more work is needed to
determine just what sorts of environments are more susceptible to
(35:31):
the bad stuff. Another interesting wrinkle in all of this
is that and and this is one Done discusses in
his book, is exactly what household dogs reveal about the
contrast between the exterior ecosystem and our interior worlds. Dogs
are amazing at bringing you filth that I think about
(35:51):
this with my dog every day. It's like every single
day he's like, let me nourish your microbiome. Well, I
think ultimately the way to look at it is the
dog is not just bringing filth in. The dog is
nurturing your filth. Like there's going to be filth if
you wish to categorize the microbial world as filth. Uh,
there's no escaping it. Um. So the dog is ultimately
(36:13):
just bringing something to the equation. So for a lot
of us, we tend to leave our our artificial interial world,
you know again, hop into another one that happens to
have wheels, travel, does to work, come back, etcetera. A
lot of us do get out into the natural world,
but there are plenty of us that don't do it
on a regular basis. If you have pets, indoor only
(36:33):
varieties contribute to the microbial stew that is your home.
But there's no beating a dog for a bridge between
inner and outer ecosystems. There's also no beating a dog
just in general. I don't want to encourage anybody, but
for starters, your dog is likely drawing you out into
the outside environment. Uh, you know, you're gonna probably hopefully
(36:54):
you're gonna take your dog on walks, You're gonna, you know,
go out into the world with it. But at the
very lead, that dog is going out to get all
up in the natural world and then bring some of
it back home. This, this has been your experience with
his a dog owner. Correct. Now, Now, there's certainly harmful
possibilities here, such as if your dog were to bring
back fleas or ticks, and this has always been an
(37:16):
issue with ancient Egyptian dog remains showing signs of brown
dog ticks, which certainly do carry pathogens. But there's also
a plethora of harmless effects and a seemingly beneficial um
impact as well. Done points out that by looking at
household microbes alone, first of all, one can tell if
there's a dog in the house at all of the time.
(37:40):
The dog just leaves a microbial footprint that's hard to
mess But beyond this, it's hard to tell at this
point what specific effects dogs and cats have on the
inner and microbial environment, because there's a lot of complexity there.
But Done says that we certainly see, especially in urban
environments with dogs, that the children in those households are
(38:01):
less prone to allergy and asthma. So the dogs might
actually be a vehicle connecting the children to nature, and
just the dirt on their paws, for instance, might be
enough uh to essentially provide some sort of uh replacement
for spending time in nature and in the natural microbial environment. Yeah.
(38:23):
This is the connection to what used to be known
as the hygiene hypothesis, though Anthesy notes that some researchers
have pointed out that this name can be kind of
misleading because the point of the hygiene hypothesis is not
that you like, shouldn't wash your hands. Uh. It's more
about having an exposure to a diverse array of microbiota
(38:44):
early in life can, if this hypothesis is correct, help
help strengthen your immune system in various ways and make
you less prone to say, allergies and asthma and things
like that. More recently, people have tried to to recoin
this thing not as the hygiene hypothesis but as the
old friends hypothesis, Like the the natural microbial world is
an old friend that we should reacquaint ourselves with, and
(39:08):
that it's good to get acquainted with early in life. Uh,
not necessarily that you like shouldn't wash your hands or
shouldn't wipe down the counter after you've been slicing chicken
or something. Yeah, now this is primarily with dogs. With
with cats, there seems to be far less of a connection. Uh.
And also it's noted that in rural environments, uh, we
see less evidence of this and the ideas that individuals
(39:29):
in a rural environment are probably getting more exposure to
to the outside of the natural world in general, so
the dog isn't going to make that much of a difference.
The dog is less of a tap of hot and
cold running exterior microbes. And I think all of that
helps to underline, you know, our desire and our inn indeed,
our need to get out of the house and interact
with nature on a regular basis. Uh. Dunn says that
(39:53):
that one day we might be able to manage our
interior microbiota in a way that will help ensure that
we're healthy and uh and that you know, everything's in balance.
But for now that's just not the case. We just
we don't understand and enough of we haven't explored, uh,
the the interior world enough to know exactly what we're
dealing with. And again, like what kind of environments are
(40:14):
are more prone to be occupied by the bad stuff
versus the the the beneficial stuff, or the stuff that
is just uh there and part of the world we
live in. Though, I think it is clear that built
environments do make a difference. Uh that we we don't
fully understand exactly what all the causal relationships are yet,
but there have definitely been measured differences that show, for example,
(40:34):
where rooms are placed and what their relationships to other
rooms where different things happen, uh, that that does affect
what kinds of microbiota we find in those rooms. Just
the example of having open windows that open to the
outside world as opposed to having a room that's all
closed off to the outside world and just ventilated by
(40:55):
you know, HVAC systems. That makes a difference to what
the microbiome of the room look like. Yeah, I mean,
I mean even if the windows don't open. You know,
we've looked at studies before, they've looked on the psychological
impact of just being able to see the outside world,
especially in hospital environment. Uh. And we do know a
few other things too, Like one of the things that
(41:15):
ant this mentions it seems to be a pretty straightforward
finding is that one good way to encourage healthy ecosystems
of microbes within the house is basically to keep the
house dry. Moisture seems to activate a lot of unwanted
fungal activity, but you can still have a lot of
healthy microbes with the house that's that's relatively dry. Uh.
You know that. She says that a lot of these
(41:37):
experts who are looking at this do not recommend using
anti microbial agents in the house, as you've been talking about.
So there are a few things we know, but yeah,
there's still a whole lot more to learn about the
interactions between our our living space architecture and our home
cleaning regimes and all that stuff with the microscopic invisible world. Yeah,
(41:58):
and it's interesting. I mean, obviously it's gonna be more
of a challenge and damper environments, say like, um, you know,
a rainforest environment. But I guess there, I guess one
is tempted to to ask the question, well, what are
the traditional modes of housing? You know, what were the
were the were the trial and error developments in housing
there versus the um that the modern solutions that have
(42:21):
been brought in from other environments without perhaps without really
taking full account of the local conditions. Yeah, that's an
interesting question. I haven't considered that. Yeah, I mean, I
don't know. You walk around any given neighborhood, right and
you you you see these trends and homes and occasionally
you'll see a home that is that it's clearly out
(42:41):
of place. But it makes you wonder, like, just how
out of place is it? Is? The design like not
suited for the you know, the energy consumption rates or
the or or just the like the the level of
the amount of sun you get in a given part
of the world, that sort of thing. Uh, you know,
I think one of the things we can take from
this episode is that homes are are far more complicated.
(43:04):
They're not just the the space we in which we live,
you know, a container for our lives. Like they they're
gonna shape who we are on a microbial level, on
a symbolic level, Um, it's uh, you know, it's it's
it's mind blowing stuff, definitely. And then sometimes you find yourself,
you know, during a pandemic, spending a lot of time
(43:27):
in your closet recording podcasts in your laundry room. Yeah,
rooms that were never designed or intended for this kind
of lengthy habitation. Luckily, my my closet here does have
an air event in it um, which has been a lifesaver.
I don't think my laundry room does around for it.
(43:47):
I have I've had a few sweaty times in here. Well,
it's this good news for when the winter sets in,
right for both of us, because I think this is
gonna be pretty cozy in here. And if you get
cold in the laundry room, you can always just turn
on the dryer. I'm really trying to get it's set
up so that I can record from a different room.
I'm trying to to make a different room in the
house less echoy, so I can get good sound and
(44:08):
not have to hunch over next to the washing machine.
I am digging an earthen pit in my backyard, which
I am told will have a really good uh sound installation.
So we'll see how that goes. Mammoth Bones Studio. Yes,
all right, Well, there you have it. Hopefully this provides
some some food for thought. Again, we're not trying to
encourage anybody to go on a any kind of a
(44:33):
killing spree in their house concerning microbes or Arthur pods
or anything like that. Uh, just we thought that as
we're spending more time looking at our homes and thinking
about getting out of nature, we should really look at
what the in the relationship between those two environments actually is.
In the meantime, if you like to check out other
episodes of Stuff to Blow Your Mind, well you can
(44:55):
find us wherever you get your podcast and wherever that
happens to be. Just make sure you rate your you
and subscribe and if you get in touch with us,
I mean clearly we'd love to hear your thoughts on
this episode. How do you relate to the content here?
How does it change or back up your own thoughts
and observations concerning your interior environment or the external world?
(45:17):
Hughes thanks as always to our excellent audio producer Seth
Nicholas Johnson. If you would like to get in touch
with us with feedback on this episode or any other,
to suggest a topic for the future, just to say hi,
you can email us at contact at stuff to Blow
your Mind dot com. Stuff to Blow Your Mind is
(45:40):
production of I Heart Radio. For more podcasts for My
Heart Radio, visit the iHeart Radio app, Apple Podcasts, or
wherever you're listening to your favorite shows proper posts, stars
(46:04):
b
Stuff To Blow Your Mind News
Hosts And Creators
Robert Lamb
Joe McCormick
Popular Podcasts
United States of Kennedy
United States of Kennedy is a podcast about our cultural fascination with the Kennedy dynasty. Every week, hosts Lyra Smith and George Civeris go into one aspect of the Kennedy story.
Stuff You Should Know
If you've ever wanted to know about champagne, satanism, the Stonewall Uprising, chaos theory, LSD, El Nino, true crime and Rosa Parks, then look no further. Josh and Chuck have you covered.
Dateline NBC
Current and classic episodes, featuring compelling true-crime mysteries, powerful documentaries and in-depth investigations. Follow now to get the latest episodes of Dateline NBC completely free, or subscribe to Dateline Premium for ad-free listening and exclusive bonus content: DatelinePremium.com