WEBVTT - The Very Dust, Part 1 0:00:03.040 --> 0:00:07.040 Welcome to Stuff to Blow Your Mind, a production of iHeartRadio. 0:00:13.000 --> 0:00:14.680 Hey, welcome to Stuff to Blow Your Mind. 0:00:14.720 --> 0:00:17.840 My name is Robert Land, and I am Joe McCormick, 0:00:17.920 --> 0:00:20.439 and today we're going to be kicking off a series 0:00:20.520 --> 0:00:23.959 about the topic of dust. I came to this one 0:00:24.440 --> 0:00:29.040 along a quite literal route. I was recently cleaning out 0:00:29.080 --> 0:00:31.960 some boxes that I had stored in a closet for years, 0:00:31.960 --> 0:00:35.000 and in the process stirred up a bunch of dust 0:00:35.080 --> 0:00:37.239 and then I just sat there breathing it while I 0:00:37.280 --> 0:00:40.160 was going through all my old stuff trying to figure 0:00:40.159 --> 0:00:42.000 out what to get rid of and all that. And 0:00:42.120 --> 0:00:46.000 this process greatly irritated my airways. But through the irritation, 0:00:46.200 --> 0:00:49.800 I ended up thinking a lot about dust and about 0:00:49.840 --> 0:00:54.240 what dust means to us. So we're surrounded by dust 0:00:54.280 --> 0:00:56.320 all the time. You know, it's in all of our homes, 0:00:57.360 --> 0:01:01.320 and it's a major concern of simple cleanliness and hygiene 0:01:01.320 --> 0:01:04.679 in the house. But it's also of huge significance to 0:01:04.760 --> 0:01:08.720 the natural environment, to cycles of weather and water, and 0:01:08.800 --> 0:01:12.759 it is of great significance to our health. Dust has 0:01:13.080 --> 0:01:16.280 so much influence on our lives. And yet it's interesting 0:01:16.360 --> 0:01:19.920 that when you think about the way dust imagery is 0:01:20.000 --> 0:01:23.760 used in like, you know, metaphors and poetry and mythology 0:01:23.800 --> 0:01:26.759 and all that. It seems to me that what dust 0:01:26.840 --> 0:01:34.120 is most often used to symbolize is uselessness, worthlessness, meaninglessness, 0:01:34.520 --> 0:01:37.240 things of no lasting significance. 0:01:37.680 --> 0:01:40.120 Yeah, I was. I picked up a Brewer's Dictionary of 0:01:40.120 --> 0:01:42.840 Phrase and fable, just looking up dust and seeing what 0:01:42.920 --> 0:01:46.360 kind of like maybe old antiquated terminology and sayings might 0:01:46.400 --> 0:01:49.600 be invoked there. And sure enough there was one for 0:01:49.840 --> 0:01:53.200 referring to money as dust, which I had not run 0:01:53.240 --> 0:01:55.559 across before. Like the idea of being like it's money, 0:01:55.560 --> 0:01:59.040 it's ultimately worthless, and therefore you call it dust. 0:02:00.160 --> 0:02:02.560 Vocabulary in that way is like a talisman against the 0:02:02.640 --> 0:02:03.520 power of money. 0:02:03.800 --> 0:02:04.360 Yeah. 0:02:04.520 --> 0:02:08.919 Yeah. Examples of this kind of usage of dust meaning 0:02:08.919 --> 0:02:13.600 that which is worthless, meaningless, you know, of no lasting significance. 0:02:14.520 --> 0:02:17.480 These go back to ancient myths and religious literature. But 0:02:17.520 --> 0:02:19.520 one of the most famous examples that came to my 0:02:19.600 --> 0:02:24.880 mind is in Shakespeare's Hamlet. It's the Quintessence of Dust 0:02:25.000 --> 0:02:29.040 monologue in Act Too Seen To where Hamlet is talking 0:02:29.040 --> 0:02:33.520 to Rosencrantz and Guildenstern, and he says famously what a 0:02:33.560 --> 0:02:36.320 piece of work is a man? How noble in reason, 0:02:36.520 --> 0:02:40.799 how infinite in faculty, in form and moving, how express 0:02:40.840 --> 0:02:44.959 and admirable in action, How like an angel in apprehension, 0:02:45.080 --> 0:02:48.120 how like a god? The beauty of the world, the 0:02:48.160 --> 0:02:51.760 paragon of animals? And yet to me, what is this 0:02:51.960 --> 0:02:56.560 quintessence of dust? So the final thought there is kind 0:02:56.600 --> 0:03:00.480 of the negation of everything he said beforehand, all of 0:03:00.480 --> 0:03:04.799 the amazing powers of humankind or beauty, or the way 0:03:04.840 --> 0:03:06.760 in which we are made in the image of God. 0:03:06.800 --> 0:03:11.960 According to Hamlet, ultimately mankind is as worthless and meaningless 0:03:12.000 --> 0:03:14.799 as the dust from which it was made. And this 0:03:14.840 --> 0:03:18.760 betrays a kind of running theme of obsession with physical death, 0:03:18.840 --> 0:03:22.799 which sort of neutralizes all meaning and renders everything pointless. 0:03:23.240 --> 0:03:25.920 I guess when Hamlet is in his depressive moods. 0:03:26.560 --> 0:03:29.800 Yeah, I mean, there's of course the line in the Bible, 0:03:29.960 --> 0:03:32.720 the King James version being for dust thou art, and 0:03:33.120 --> 0:03:36.560 unto dust, thou shalt thou return, which you know, is 0:03:36.560 --> 0:03:39.080 pretty on point, but I think it also misses all 0:03:39.080 --> 0:03:41.480 of the dust in between, because it will be discussing 0:03:41.600 --> 0:03:44.680 like dust is just so ubiquitous. It's not just like 0:03:44.760 --> 0:03:46.520 that thing at the beginning of the end, like it's 0:03:46.560 --> 0:03:49.200 everywhere in between two, Like it's in the living body, 0:03:49.680 --> 0:03:52.960 it's brought into the living body, it's in the living world, 0:03:53.600 --> 0:03:55.320 and it's out there in the cosmos. 0:03:55.720 --> 0:03:58.440 Oh yeah, well that's kind of a beautiful observation. I 0:03:58.600 --> 0:04:01.160 like that counterpoint that, of course life in many ways 0:04:01.200 --> 0:04:03.680 is dust. There is a dust of life in the 0:04:03.720 --> 0:04:06.360 same way that there is a dust of death. But 0:04:06.400 --> 0:04:09.960 I also still think that it's intriguing and curious that 0:04:10.480 --> 0:04:14.520 there's so much literature and poetry and stuff where the 0:04:14.600 --> 0:04:19.480 image of dust seems to emphasize almost cosmic horror, you know, 0:04:19.560 --> 0:04:23.719 the great vast emptiness and negation of all of life's 0:04:23.760 --> 0:04:27.760 grandiose illusions of worth, Like why is that? What is 0:04:28.320 --> 0:04:30.040 it about if you look at a pile of dust? 0:04:30.160 --> 0:04:34.480 What is it about a pile of fine, granular particles 0:04:34.520 --> 0:04:39.480 of matter that takes on such a powerfully depressing symbolic heft. 0:04:40.040 --> 0:04:41.560 Yeah, fear and a handful of dust. 0:04:41.680 --> 0:04:43.919 Right, So, I guess a good place to start for 0:04:43.960 --> 0:04:47.159 the series is to tackle the question quite literally, what 0:04:47.440 --> 0:04:50.640 is dust in a physical sense? And I found that 0:04:50.960 --> 0:04:54.800 in scientific usage, the stuff that we call dust is 0:04:54.839 --> 0:04:59.640 often broken down with more specific terminology depending on the field. 0:05:00.080 --> 0:05:02.640 But I did find a book actually that gave what 0:05:02.680 --> 0:05:05.560 I thought was a really good definition of dust generally. 0:05:06.160 --> 0:05:08.480 So I came across this because I was reading an 0:05:08.480 --> 0:05:12.240 interview in Wired magazine with an author named Jay Owens. 0:05:12.640 --> 0:05:15.200 She's the author of a twenty twenty three book called 0:05:15.800 --> 0:05:19.760 Dust The Modern World in a Trillion Particles, and I 0:05:19.839 --> 0:05:21.560 like the author's thoughts, so I ended up buying the 0:05:21.560 --> 0:05:23.920 book to explore the topic more. And by the way, 0:05:24.000 --> 0:05:26.520 this book isn't purely about like the science of dust. 0:05:26.560 --> 0:05:30.080 It delves into politics and religion and philosophy and so forth. 0:05:30.960 --> 0:05:35.040 But in terms of a physical definition, the definition of 0:05:35.120 --> 0:05:40.479 dust the author uses is tiny flying particles. This is 0:05:40.480 --> 0:05:44.720 sort of a compromise that works across multiple domains, and personally, 0:05:44.880 --> 0:05:47.320 I think it works quite well because it captures the 0:05:47.440 --> 0:05:52.159 three main properties common to all the things we call dust, 0:05:52.760 --> 0:05:57.320 so tiny flying particles. First, we look at particles, meaning 0:05:57.400 --> 0:06:02.080 pieces of solid matter. In the atmospheric sciences, people often 0:06:02.160 --> 0:06:06.719 talk about the idea of aerosols, meaning particles or droplets 0:06:06.760 --> 0:06:10.680 that are suspended in the air, like suspended within a gas. 0:06:11.120 --> 0:06:14.400 But this includes things that obviously aren't what people mean 0:06:14.480 --> 0:06:18.599 by dust, such as floating liquid droplets like mist or fog, 0:06:19.560 --> 0:06:22.880 and many types of air pollution contain a mix of 0:06:22.960 --> 0:06:26.719 liquids and solid particulates. But in common usage, I think 0:06:26.839 --> 0:06:31.400 dust means a substance made mostly of solid particles. Right. 0:06:32.120 --> 0:06:35.479 Second element of tiny flying particles we can look at tiny. 0:06:36.279 --> 0:06:40.120 There is no universally agreed upon size for dust particles, 0:06:40.160 --> 0:06:44.000 but based on reading Owens and other sources, it seems 0:06:44.040 --> 0:06:47.080 that what we call dust is always made of particles 0:06:47.160 --> 0:06:50.560 less than a millimeter in diameter, and usually on a 0:06:50.600 --> 0:06:54.120 scale of one hundred to one thousand times smaller than 0:06:54.160 --> 0:06:58.240 a millimeter, which means between one and ten micrometers or 0:06:58.360 --> 0:07:02.560 microns in size. So again, a micrometer is one one 0:07:02.640 --> 0:07:06.600 thousandth of a millimeter. And for comparison, Owen's notes that 0:07:06.760 --> 0:07:10.400 human hair is on average somewhere between seventy and ninety 0:07:10.520 --> 0:07:13.760 micrometers in width. So if I did the math on this, right, 0:07:14.480 --> 0:07:18.240 what we call dust is usually somewhere between one percent 0:07:18.320 --> 0:07:20.920 to about fifteen percent the width of a human hair. 0:07:21.600 --> 0:07:24.880 Right, So very often the particles of dust we're talking about, 0:07:24.920 --> 0:07:28.240 they're not even really visible to the human eye. Though 0:07:28.280 --> 0:07:30.840 again you're going to have some particles that are larger than. 0:07:30.760 --> 0:07:33.840 Others exactly, and they're things that are often not visible 0:07:34.000 --> 0:07:36.280 on their own but are visible in aggregate. 0:07:36.720 --> 0:07:39.440 Right. So like when you walk in and you decide 0:07:39.480 --> 0:07:41.240 to sit down at your hobby table, I don't know, 0:07:41.280 --> 0:07:45.120 your typewriter, whatever air of your house is beloved but 0:07:45.160 --> 0:07:48.400 perhaps neglected, and you say, who put all this dust here? 0:07:48.640 --> 0:07:50.400 You know you I can think of it in terms 0:07:50.400 --> 0:07:52.360 of who put all of these dust particles here on 0:07:52.440 --> 0:07:55.080 my hobby table? You know it's you see it again 0:07:55.120 --> 0:07:57.960 in aggregate, like you said, and how did they get there? Well, 0:07:58.000 --> 0:08:00.760 that goes right into your next point, right, So. 0:08:00.680 --> 0:08:04.760 The third part of Owen's definition tiny flying particles is flying. 0:08:05.600 --> 0:08:08.600 So a core element of dust is that dust particles 0:08:08.600 --> 0:08:11.760 can easily be stirred up by airflow and other types 0:08:11.800 --> 0:08:15.600 of physical agitation, and then they float in the atmosphere 0:08:15.680 --> 0:08:19.760 for a significant time before settling down. So you might 0:08:19.880 --> 0:08:23.200 think of, say, grains of sand on the beach as 0:08:23.320 --> 0:08:26.320 tiny particles, but a lot of those grains are large 0:08:26.400 --> 0:08:29.040 enough that if you grab a fistful of sand off 0:08:29.040 --> 0:08:30.800 of beach and you throw it up in the air, 0:08:31.360 --> 0:08:34.000 those grains of sand will plummet straight back down to 0:08:34.040 --> 0:08:37.520 the ground. However, some of the mass of that fistful 0:08:37.559 --> 0:08:40.480 of sand will probably be made up of dust sized 0:08:40.520 --> 0:08:43.520 particles which will remain in the air as a cloud 0:08:43.640 --> 0:08:46.000 for some time, while the larger grains just fall to 0:08:46.040 --> 0:08:49.520 the earth. So a characteristic feature of dust is its 0:08:49.559 --> 0:08:52.920 ability to float in the air but also to travel 0:08:53.120 --> 0:08:56.360 on the air. So this made me think about how 0:08:56.440 --> 0:08:58.680 when you see a surface in your house, so maybe 0:08:58.720 --> 0:09:03.679 a bookshelf in dust, you don't look directly above it 0:09:03.880 --> 0:09:06.480 to see where the dust was falling from. Maybe you 0:09:06.520 --> 0:09:09.640 do if you see larger pieces of something on top 0:09:09.679 --> 0:09:13.000 of it. But if it's just dust, we understand that 0:09:13.120 --> 0:09:16.800 dust migrates on currents of air and it settles somewhere 0:09:16.840 --> 0:09:20.160 potentially very far from its origin. So it doesn't just fall, 0:09:20.200 --> 0:09:24.400 but it travels. So that's the rundown of Owen's definition, 0:09:24.440 --> 0:09:26.160 and I think it's a good one. Dust is made 0:09:26.240 --> 0:09:30.439 of tiny flying particles. But there's another sense of the 0:09:30.520 --> 0:09:34.160 question what is dust? And that sense is what is 0:09:34.200 --> 0:09:37.959 it made of? And this is another interesting point that 0:09:38.080 --> 0:09:40.800 Owen's race is. In the introduction of her book, she 0:09:41.040 --> 0:09:44.880 argues that dust is also defined by quote A certain 0:09:45.040 --> 0:09:49.680 loss of context, an inherent formlessness. And that might sound 0:09:50.000 --> 0:09:52.840 maybe overly poetic, but I think that's actually a quite 0:09:52.920 --> 0:09:56.800 good specific point. It's the fact that dust is made 0:09:56.800 --> 0:10:01.080 of many different substances and we don't know what they are, 0:10:01.480 --> 0:10:04.040 and that is what makes it dust. Because if we 0:10:04.120 --> 0:10:06.959 did know exactly what it was made of, and we 0:10:07.000 --> 0:10:10.400 saw it, say, pouring in fine floating grains from its 0:10:10.400 --> 0:10:13.720 original source, we probably wouldn't call it dust. We would 0:10:13.800 --> 0:10:16.520 call it whatever it was. We might say, look, that 0:10:16.679 --> 0:10:19.760 is oak pollen, or that is pet dand or floating 0:10:19.760 --> 0:10:22.960 off of my dog, or that is silica powder coming 0:10:23.000 --> 0:10:25.800 out of a container, or it's you know, concrete dust 0:10:26.080 --> 0:10:29.360 coming up off of a concrete being mixed in a bucket. 0:10:30.120 --> 0:10:33.520 It is the loss of its original context and the 0:10:33.600 --> 0:10:38.800 mixing together with other such substances lost from their original context, 0:10:38.840 --> 0:10:44.440 to that blending together that makes these unknown particles simply dust. 0:10:44.840 --> 0:10:47.000 Yeah, it's only in the Hollywood context that you have 0:10:47.040 --> 0:10:51.200 a definite source of dust. I was looking around at 0:10:51.240 --> 0:10:55.000 some of these gadgets earlier. You can pick up like 0:10:55.040 --> 0:10:58.280 a handcrake dust gun for pretty cheap, and then you 0:10:58.320 --> 0:11:02.560 have you know, far more advanced models as well. Where 0:11:02.600 --> 0:11:06.559 you would actually have the dust particles inside of a 0:11:07.520 --> 0:11:11.040 reservoir and then you are spraying them out onto a surface. 0:11:11.320 --> 0:11:13.240 So you know, you can get that like nice haunted 0:11:13.360 --> 0:11:16.679 manner layer of dust so that your lead actor can 0:11:16.720 --> 0:11:20.240 come in, you know, perhaps drag their finger over the 0:11:20.559 --> 0:11:23.560 surface of a piano and then look around at the 0:11:23.600 --> 0:11:25.600 haunted surroundings. But then you have to do another take 0:11:26.040 --> 0:11:29.280 and spend several minutes like removing all the dust and 0:11:29.280 --> 0:11:32.880 then apply reapplying the dust. I've heard accounts of that 0:11:32.920 --> 0:11:34.760 sort of thing in movie production before. 0:11:36.080 --> 0:11:39.520 Now, what about when the actor who's like been through 0:11:39.559 --> 0:11:41.160 a lot, like you know, they're coming in out of 0:11:41.160 --> 0:11:43.360 the desert or something and they pat themselves and the 0:11:43.440 --> 0:11:45.360 dust comes off of them in a cloud. I wonder 0:11:45.640 --> 0:11:47.720 do they have to get redusted again each take? 0:11:48.080 --> 0:11:50.559 I bet so. I mean there's all sorts of I mean, 0:11:50.559 --> 0:11:53.760 it's kind of the reverse of the whole like having 0:11:53.800 --> 0:11:57.959 to polish Darth Vader's helmet, you know, constantly to make 0:11:58.000 --> 0:12:00.520 sure sure that you're not getting any smudges on there 0:12:00.600 --> 0:12:04.640 or anything. But yeah, you're interested in the cinematic dusting. Yeah, 0:12:04.640 --> 0:12:07.200 you can go to various websites and you can look 0:12:07.240 --> 0:12:10.000 up the movie dust. You can buy it in various sizes, 0:12:10.600 --> 0:12:14.640 various instruments to to spray the movie dust around. 0:12:14.960 --> 0:12:26.640 It's kind of fun, okay. 0:12:26.679 --> 0:12:30.319 So dust is the name for tiny flying particles from 0:12:30.360 --> 0:12:34.000 an unknown source. But when we actually get in there 0:12:34.160 --> 0:12:37.160 with the microscope and the lab equipment, we of course 0:12:37.200 --> 0:12:40.240 can study dust and figure out where it comes from 0:12:40.400 --> 0:12:44.040 and what it's made of. So what is dust most 0:12:44.240 --> 0:12:47.440 often made of when we encounter it? Of course, it 0:12:47.520 --> 0:12:51.240 depends where you're taking the sample from. Worldwide, Owen says 0:12:51.240 --> 0:12:54.480 the most prevalent type of dust is mineral in origin, 0:12:54.679 --> 0:12:58.439 so tiny grains of rock broken apart by natural processes 0:12:58.559 --> 0:13:01.520 or worn down by erosion, and you know they come 0:13:01.600 --> 0:13:05.120 from the rocks, the rock layers of earth, and these 0:13:05.160 --> 0:13:10.120 minerals are born aloft by winds and other primarily by winds, 0:13:10.160 --> 0:13:14.600 but by whatever source agitates them. Inside a home, a 0:13:14.640 --> 0:13:16.679 lot of the dust you will find still does come 0:13:16.720 --> 0:13:19.880 from soil tracked in or blown in from the outside, 0:13:20.240 --> 0:13:23.880 but there are also non soil particles carried in from outside, 0:13:23.920 --> 0:13:28.400 including pollen and particulates in the air that come from combustion, 0:13:28.679 --> 0:13:32.560 such as soot. Soot can be a big constituent of dust. 0:13:33.240 --> 0:13:37.080 Also soot from any combustion happening inside the house. Cooking 0:13:37.240 --> 0:13:41.600 in the house is a large source of particles inside 0:13:41.640 --> 0:13:44.439 the air of a home. But also there are, I 0:13:44.480 --> 0:13:46.920 don't know, depending on your point of view, perhaps grosser 0:13:47.080 --> 0:13:51.280 sources of dust, but hair from humans and pets, dead 0:13:51.400 --> 0:13:54.679 skin cells from humans, as well as pet dander, you know, 0:13:54.679 --> 0:13:57.679 stuff coming off of the skin of pets. There are 0:13:57.840 --> 0:14:03.040 fibers from inorganic sources in the home, fibers from carpets, furniture, 0:14:03.200 --> 0:14:08.120 and clothing, other organic particles like pieces of dead insects, 0:14:08.480 --> 0:14:12.559 wonderful little cockroach crumbs all over the house. And then 0:14:12.760 --> 0:14:16.080 just you know, random stuff, tiny bits of random garbage 0:14:16.120 --> 0:14:18.920 like pieces of paper, waste, and plastic. 0:14:19.440 --> 0:14:21.720 This episode is brought to you by dusting. Have you 0:14:21.800 --> 0:14:23.880 dusted today? Don't you want to? Now? 0:14:24.360 --> 0:14:27.000 Oh, let me give you another reason, because among all that, 0:14:27.080 --> 0:14:31.320 there is something else, some part of the dust itself 0:14:31.360 --> 0:14:35.920 which is alive and feeding and growing and living amongst 0:14:36.000 --> 0:14:41.720 us always, and that is dust mites. I got really 0:14:41.720 --> 0:14:45.400 interested in dust mites for this episode, so I wanted 0:14:45.400 --> 0:14:49.320 to do a little sidebar here on dust mites. So 0:14:50.120 --> 0:14:53.280 there are many types of mites. House dust mites are 0:14:53.560 --> 0:14:57.600 one particular branch of them, belonging to the family pyro glyffidy. 0:14:58.280 --> 0:15:00.800 And I was trying to parse the name. That name 0:15:00.840 --> 0:15:04.440 through its Greek roots pyro is fire and glyphid would 0:15:04.440 --> 0:15:07.120 seem to mean like carving. But then I found a 0:15:07.200 --> 0:15:10.120 source saying exactly what it means. And the name of 0:15:10.160 --> 0:15:14.120 the pyroglyphid mites comes from the fact that these dust 0:15:14.160 --> 0:15:17.600 mites can cause irritation on the skin, rashes and irritation 0:15:17.720 --> 0:15:21.480 on human skin, like burns from fires, like fire carvings 0:15:21.520 --> 0:15:25.400 on the skin. So house dust mites are microscopic bugs 0:15:25.400 --> 0:15:28.120 that can be found all throughout human dwellings. They are 0:15:28.320 --> 0:15:32.800 They're not insects. Instead, they are eight legged arachnids, more 0:15:32.840 --> 0:15:37.520 closely related to spiders than to insects. They are microscopic 0:15:37.680 --> 0:15:42.520 and can possibly be seen without the aid of a microscope, 0:15:42.560 --> 0:15:47.440 but would rarely be noticed without visual magnification. Their body 0:15:47.520 --> 0:15:50.640 lengths are on the order of a few hundred micrometers. 0:15:51.680 --> 0:15:55.440 So these dust mites are in many human homes, living 0:15:55.480 --> 0:15:59.320 all around us. How do these dust mites make a living? 0:15:59.400 --> 0:16:02.280 What are they doing in our homes? You might be 0:16:02.320 --> 0:16:04.840 able to guess that by knowing the genus name of 0:16:04.880 --> 0:16:07.720 a couple of the most common varieties of house dustmites. 0:16:08.000 --> 0:16:14.200 That genus name is Dermatophagoides skin eaters. They are skin 0:16:14.360 --> 0:16:18.200 eaters generally dead skin that is already flaked off of 0:16:18.240 --> 0:16:21.160 your body, so fortunately you know, usually they can they 0:16:21.160 --> 0:16:23.320 can find something that's not still attached to you. 0:16:23.920 --> 0:16:26.080 Polite skin eaters they. 0:16:26.040 --> 0:16:29.960 Hunt for these discarded rafts of mammal skin in the 0:16:30.120 --> 0:16:35.160 microforests of our homes, in carpets, mattresses, in the soft 0:16:35.200 --> 0:16:39.160 weave of furniture. But despite their tiny size and the 0:16:39.200 --> 0:16:41.600 fact that they're usually looking for stuff that has already 0:16:41.640 --> 0:16:46.600 fallen off of you, house duestomites and their feces are 0:16:46.640 --> 0:16:50.080 a major problem for humans. They are a major source 0:16:50.160 --> 0:16:53.520 of allergens within the home. In fact, according to one 0:16:53.520 --> 0:16:55.360 paper that I'm going to get to in just a second, 0:16:56.080 --> 0:17:01.440 pyroglyphid mites are the single greatest source of allergic symptoms 0:17:01.480 --> 0:17:02.680 in human beings. 0:17:02.920 --> 0:17:03.240 Total. 0:17:04.200 --> 0:17:07.000 The authors of the paper estimate that they cause allergies 0:17:07.040 --> 0:17:10.600 in somewhere between sixty five million and one point two 0:17:10.760 --> 0:17:11.719 billion people. 0:17:12.240 --> 0:17:14.960 This episode is also brought to you by washing your sheets. 0:17:15.359 --> 0:17:18.320 Have you washed your sheets lately, don't you want to? 0:17:18.359 --> 0:17:21.080 Now, I want to clarify that these are these are 0:17:21.080 --> 0:17:24.320 different than bedbugs, by the way, Yes, yeah, dust mites. 0:17:24.359 --> 0:17:26.240 I mean they'll they'll find them all over the place. 0:17:26.240 --> 0:17:29.800 They're not the same as bedbugs. You know, bed bugs 0:17:29.800 --> 0:17:33.040 are looking for a blood meal. The dustimites are looking 0:17:33.040 --> 0:17:36.040 for the skin flakes. Now here's maybe a good point 0:17:36.080 --> 0:17:38.320 to describe what they look like, Rob. I've attached some 0:17:38.480 --> 0:17:45.000 pictures of dustimites for you. These are several micrographs of pyroglyphids. 0:17:45.040 --> 0:17:46.240 So what do you see here? 0:17:46.840 --> 0:17:49.000 I mean they basically look like the head crabs from 0:17:49.040 --> 0:17:50.959 the old Half Live video games. 0:17:51.359 --> 0:17:55.320 That's perfect, That's exactly it. Yeah, one of these. So 0:17:55.359 --> 0:17:58.480 some of these are like scanning electron micrographs. I guess that. 0:17:58.760 --> 0:18:02.000 You know, they're a lot of texture. It's false color, 0:18:02.080 --> 0:18:05.359 I guess. But in the one shown from right above, 0:18:05.440 --> 0:18:08.040 I mean they've got a bit of a spidery appearance 0:18:08.080 --> 0:18:10.960 because they have eight legs and these you know, the 0:18:10.960 --> 0:18:13.480 these mouth parts up in the front, the kind of 0:18:13.840 --> 0:18:17.560 finger fangs sort of. But also one of these big 0:18:17.600 --> 0:18:19.520 pictures we have to look at, the skin just looks 0:18:19.600 --> 0:18:22.280 kind of like wrinkly and deflated. It's like a half 0:18:22.280 --> 0:18:23.600 inflated basketball. 0:18:24.200 --> 0:18:26.439 Yeah yeah. I'd also like how the wrinkle on this 0:18:26.480 --> 0:18:29.040 particular image looks kind of like a mouth, So it 0:18:29.119 --> 0:18:31.600 kind of looks like some sort of a whiskery Muppet creature, 0:18:32.840 --> 0:18:36.240 like from like a nineties Muppet creature, not a classic Muppet. 0:18:36.480 --> 0:18:41.160 Oh, it looks exactly like either the Nightmare Before Christmas, 0:18:41.240 --> 0:18:44.440 the Oogie Boogieman, or looks like the sorting hat from 0:18:44.480 --> 0:18:45.560 the Harry Potter movies. 0:18:45.720 --> 0:18:45.960 Yeah. 0:18:46.040 --> 0:18:49.080 Yeah. The really magnified images I have for you are 0:18:49.119 --> 0:18:52.440 the the false color images, but the ones in true 0:18:52.440 --> 0:18:55.800 color you can see that they're generally kind of white 0:18:55.840 --> 0:18:58.520 in appearance. Again, they're very very small, so hard to 0:18:58.520 --> 0:19:01.480 see with the naked eye, but kind of white and 0:19:01.560 --> 0:19:05.280 a little bit grub like in appearance, with the limbs 0:19:05.320 --> 0:19:07.679 coming out in the front in a larger sort of 0:19:08.320 --> 0:19:12.160 white bulb of a body extending behind. Now, I wanted 0:19:12.240 --> 0:19:14.439 to come back and take a brief look at a 0:19:14.560 --> 0:19:17.440 dust mite paper that I just brought up a minute ago. 0:19:18.200 --> 0:19:23.000 This is a paper called is Permanent Parasitism Reversible Critical 0:19:23.040 --> 0:19:26.679 Evidence from early evolution of house dust mites. This is 0:19:26.680 --> 0:19:31.199 by Pavel B. Klimov and Barry O'Connor published in Systematic 0:19:31.240 --> 0:19:34.680 Biology in twenty thirteen, and there are a couple of 0:19:34.720 --> 0:19:36.480 things I wanted to talk about here. First is just 0:19:36.560 --> 0:19:42.879 a passage directly about the allergenic quality of these mites, 0:19:42.920 --> 0:19:46.520 about why the feces of pyroglyphid mites are so prone 0:19:46.520 --> 0:19:50.360 to cause irritation and allergic reaction in humans the author's 0:19:50.440 --> 0:19:54.960 right quote. Dust mites feed on organic debris such as 0:19:55.000 --> 0:20:00.000 shed skin and flourish in nests of vertebrates, including human dwellings. 0:20:00.600 --> 0:20:04.600 The mites severe allergenic properties are linked to their powerful 0:20:04.800 --> 0:20:11.800 digestive and molting enzymes, salivary secretions, and other water soluble molecules. 0:20:11.960 --> 0:20:17.240 For example, large quantities of digestive enzymes accumulate in mite's 0:20:17.320 --> 0:20:22.800 fecal material, minute particles that can easily become airborne when 0:20:22.880 --> 0:20:27.639 inhaled or in contact with skin. The residual mite enzymes 0:20:27.680 --> 0:20:31.959 may break up tight junctions between epithelial cells and trigger 0:20:32.080 --> 0:20:37.000 allergic reactions. So these mites they make tiny poops, and 0:20:37.040 --> 0:20:40.560 their tiny poops are full of the digestive enzymes that 0:20:40.600 --> 0:20:43.560 they use to break down their food, and their food 0:20:43.840 --> 0:20:48.359 is human skin flakes and in the broader context, things 0:20:48.359 --> 0:20:52.080 that contain keratin, like of course skin cells, but also 0:20:52.160 --> 0:20:57.080 like bird feathers, which these animals also eat. So it 0:20:57.200 --> 0:21:01.720 is like they have evolved a digestive enzyme that makes 0:21:01.760 --> 0:21:05.679 it possible for them to eat difficult to digest things 0:21:05.720 --> 0:21:08.679 that fall off of us and get nutrition out of that. 0:21:09.200 --> 0:21:12.320 And then they poop, and their poop contains the enzymes 0:21:12.359 --> 0:21:14.720 that allow them to break that stuff down. And then 0:21:14.720 --> 0:21:16.960 that poop gets stirred up in the air and becomes 0:21:17.000 --> 0:21:19.240 part of the dust in our homes and gets on 0:21:19.280 --> 0:21:23.240 people's skin and in their airways and so forth. But anyway, 0:21:23.480 --> 0:21:26.080 to come to a bigger picture issue, the real point 0:21:26.119 --> 0:21:29.560 of this paper is related to the evolutionary history of 0:21:29.600 --> 0:21:34.480 the house dust might how did these microscopic animals end 0:21:34.560 --> 0:21:37.359 up living this way, crawling through the jungles of the 0:21:37.359 --> 0:21:40.399 couch cushions, you know, getting into the area rug to 0:21:40.520 --> 0:21:44.119 munch on our dead skin flakes. How did they end 0:21:44.200 --> 0:21:47.760 up that way? Well, the authors of this paper used 0:21:47.920 --> 0:21:52.640 genomic evidence cross comparing different lineages of mites of these 0:21:52.680 --> 0:21:58.040 pyroglyphids and related organisms to show that these free living 0:21:58.119 --> 0:22:01.360 mites within our homes. It used to be even closer 0:22:01.400 --> 0:22:07.119 companions than they are now. They evolved from fully obligate 0:22:07.320 --> 0:22:12.160 permanent parasites of warm blooded vertebrates like birds and mammals 0:22:12.640 --> 0:22:16.439 the author's right quote. We propose that parasitic ancestors of 0:22:16.480 --> 0:22:22.439 pyroglyphids shifted to nests of vertebrates. Later, the nest inhabiting 0:22:22.480 --> 0:22:26.879 pyroglyphids expanded into human dwellings to become a major source 0:22:27.000 --> 0:22:31.760 of allergens. So these evolved from creatures that were once 0:22:32.080 --> 0:22:37.640 free living organisms and then evolved a tight specialized parasite 0:22:37.720 --> 0:22:41.600 relationship with warm blooded vertebrates like mammals and birds and 0:22:41.600 --> 0:22:46.199 would live directly on the host, and then shifted away 0:22:46.280 --> 0:22:50.159 from that tight specific parasitic relationship to be to have 0:22:50.200 --> 0:22:53.200 a more loose relationship, to be free living into somewhat, 0:22:53.280 --> 0:22:56.359 you know, to sort of scavenge what falls off of 0:22:56.600 --> 0:23:00.640 the host animal or the former host animal. And that's 0:23:00.640 --> 0:23:05.760 interesting because this kind of despecialization from a tight parasite 0:23:05.800 --> 0:23:10.760 host relationship to a more generalized free living dust no 0:23:10.880 --> 0:23:16.080 mad lifestyle was considered quite unusual, something that is rarely 0:23:16.080 --> 0:23:19.399 observed in evolution, and at some times in the past 0:23:19.680 --> 0:23:23.040 was thought impossible. But it's clearly not impossible. It's just 0:23:23.640 --> 0:23:27.280 evolutionarily difficult to do to get out of that sort 0:23:27.320 --> 0:23:30.879 of tight, tight adaptive dead end where you are stuck 0:23:30.920 --> 0:23:33.800 in a relationship with this host animal to become a 0:23:33.800 --> 0:23:35.920 little more of a generalist and get a little bit 0:23:35.920 --> 0:23:38.000 more distance and still be able to survive. 0:23:38.560 --> 0:23:41.960 What's like, it's almost like evolutionarily they survive the passage 0:23:41.960 --> 0:23:46.320 to the promised land, the promised land being the augmented 0:23:46.480 --> 0:23:48.240 environment that is the human home. 0:23:48.760 --> 0:23:51.640 Oh that's interesting. Yeah, I mean they have to they 0:23:51.640 --> 0:23:54.720 still have to be very specialized to survive within the 0:23:54.800 --> 0:23:58.040 human home. They have to be able to tolerate different 0:23:58.080 --> 0:24:00.840