Listener Mail: Supernaut

messages that you've sent in over the past cycle. Looks like this. First one comes from Chris. Chris says, hey, guys, love the show. Something that blew my mind recently has to do with evolution. Here it goes in the ancient timeline of life on Earth, sharks are older than trees. I always thought of plants as first. Knowing that sharks were swimming around for a hundred million years before there were even trees blew my mind. Thanks Chris, Chris. Yeah,

I I love stuff like this. So to fill in some detail on this claim, I would say that this statement is true, though it depends a little bit on how strict your definitions of a shark are um there there's some debate, I guess, about what counts as evidence

of the first shark. But for reference, I just looked up the timeline summarized by the Natural History Museum of London, and according to them, there are a few fossil scales that appear to come from shark like animals, dating all the way back to the Ordovician period, So that's four hundred and fifty million years ago, which is mind bogglingly old.

The Ortivician is the first geologic period after the Cambrian, and if you remember, we've done episodes on this in the past, the Cambrian is when we first see the explosion in divers city of animal body plans, animal body plans with hard parts that leave fossil traces, and so this is the age of the triobytes, of course famously, but also these these amazing creatures like Anomala carress, this undulating, soft bodied predator with a ring shaped crusher mouth and

little face tentacles that look like shrimp anomal a caress actually means anomalous shrimp or weird shrimp. And uh creatures like Hallucigenia, which is the wandering spike worm. Uh and so so that's the Cambrian. But then after that we enter the Ordovician period and there we yes, we do see evidence of scales, but not teeth. But the scales look like they may have belonged to some kind of ancestral shark or creature that that overtime became sharks. So

that evidence is is a maybe. But then by the early Devonian period, about four and ten million years ago, there is clear fossil evidence of shark teeth from a fish called Dolotas problematicus, which was beginning to show some of the signs of shark like anatomy, such as in

the teeth and the jaw. And there's another early shark from the Devonian that I was reading about that I think we don't know much about, but it's called Leonotas l e O n O d u s. And the the only thing that I could really find about this one had to do with its teeth. If you get a chance, you should look up the teeth of the Leonoda shark. These creatures were about four million years old, and its teeth are not the serrated triangles or or the murder spikes you might think of in in shark

mouth today. These look like well they look like the devil horns. They look like somebody in a metal show they go, they throw up the devil horns. They're these little y shaped forks, which makes me wonder what kind of prey this animal was eating. What do you bite with a bunch of little spiky, y shaped forks? I don't know. But meanwhile, the evolution of trees is also an interesting subject. I think the first things we would identify as trees, meaning tall vascular plants on dry land

with woody stems. These show up I think in the mid to late Devonian period, so maybe around three hundred ninety to three hundred and eighty million years ago, somewhere in that range. And in fact, the proliferation of land plants, including trees during the mid to late Devonian is one of the hypothesized causes of the big mass extinction event that happened at the end of the Devonian period. Now, of course, this is not a settled issue. There are

a bunch of different ideas about what could have caused it. Uh, you know, you have the regular culprits, things like US impacts from space or a massive volcanic eruptions. Um. But at least one idea that has been advanced is that as the continents were covered in plants and forests during the Devonian and as as the land turn green, suddenly a large amount of the carbon in the atmosphere was removed.

Because remember this really weird fact. Plants the parts of plants that is not water, that is mostly built out of atoms that were originally in the air. So carbon, the carbon in wood in a tree trunk comes from atmospheric c O two that plants ingest and then they use the energy from sunlight to power the chemical reaction uh we know as photosynthesis, So it reacts CEO two with water to produce carbohydrates and oxygen as a byproduct.

So you have the proliferation of forests that might have removed a bunch of carbon from the atmosphere to cause a sort of anti greenhouse effect leading to deadly rapid cooling. But again, there are other possible explanations for the for the late Devonian extinctions, so we don't really know for sure. However, one last cool thing to notice when you put sharks and trees side by side, so it does look like

the sharks came first. But the other thing to notice is that they both appear to have had a sort of flourishing age of diversification and dominance in the period right after the Devonian, which is known as the Carboniferous So the Carboniferous period lasted from roughly three hundred and sixty to about three hundred million years ago, and it is named after the fact that this is the geologic strata that we first find packed with lots of coal.

Carboniferous means coal carrying or full of coal, and coal is of course a form of fossil carbon that came largely from dead plant matter, including trees, especially trees that

grew in low lying wetlands and swamps. So in these vast uh you know, continents full of low lying wetlands and wet forests and swamps, you'd have plants dying they fall down there there, or carbon content it's fossilized into coal, and then of course in the industrial revolution we we dig that up and that that turns into the energy that powers the development of modern civilization. But the Carboniferous period is also sometimes called the Golden Age of sharks.

That same article I was looking at by the by the London Natural History Museum referred to it as the Golden Age of sharks. There's a great question why did sharks thrive in this period? Why this great diversification of sharks? And that's not known for sure. But one idea that I was reading at a great website called Elasmo research dot org. That's a shark science website that I think is mostly or entirely authored by a marine biologist named

our Aiden Martin. I was reading on that site the idea that possibly sharks thrived in this period because at the at the Late Devonian extinction, another group of marine predators called the plaquaderms were wiped out. The plaqueoderms, if you've never seen pictures of them, you should definitely look them up there. They're great. They were armored fishes fish fish you would see with like plates around their head

and sort of plate like jaws and mouths. Uh So, one good one to look up is called dunk Leosteus d U N K l e O S t e U S. Dunk Leosteus. And if you can find an image with a human for scale, or even better, if you can stand next to an arrangement of their armored head plates in a museum. It's a nightmare. You know. I would much rather face down a great white shark or I don't know, maybe even a megalodon. Is something

about it's it's it's terrifying and awesome. But but the idea is that maybe with the competition of these plaqueoderms gone because they were wiped out at the end of the Devonian, maybe then sharks could expand and fill new niches and diversify. So anyway, thanks for kicking this off, Chris, but I wanted to give you an another one. So, yes, it appears sharks are older than trees. But did you

know that mammals are older than bees. As with the previous case, there's some debate about where where you should start, you know what, at what point on the lineage you should say, okay, now these are mammals, because of course mammals are part of a lineage going back to the synapsids that lived even before the dinosaurs, you know, the dimetrodon So again you could debate about the where the

best place to put their beginning is. But small furry sort of rodent ish critters that we would probably recognize as mammals existed during the reign of dinosaurs, with a number of fossils from the Jurassic Period between about a hundred and fifty and two hundred million years ago. Meanwhile, bees pop up later I think closer to a hundred and thirty million years ago. Anyway, thank you, Chris. Okay, this next message comes from Steven and it's in Risk

wants to the series we did on thirst. Steven says, Dear Joe and Rob. As a recent microbiology graduate, I was delighted when you started talking about rabies, the horse hair worm and their relationships with their hosts thirst, and I remember that this was in the context of us talking about ways that UH disease causing pathogens and parasites will alter the host behavior in order to help themselves spread or reach another part of their their life cycle.

So in the same way that a respiratory infection will make you cough and sneeze and spit more of the germs onto other people to to to spread it around faster, the rabies virus causes a series of behavioral modifications that that help it spread through bite. So you get bitten by an animal with rabies um and the the infected saliva put some of the virus into your muscle tissue,

it spreads to the nervous system. Uh that that is facilitated by the fact that rabies tends to cause a kind of confusion, irritability aggression in its later stages, and that it makes it hard for the host to swallow, so it can't the The person or animal that's infected has difficulty or even finds it impossible to drink water, un thus can't wash all this infectious saliva out of its mouth, so each bite is supercharged as a vector

of new infection. But Steven goes on to say, I thought I would add to the conversation with another interesting parasite that hijacks our need for water. The guinea worm is a parasitic worm whose life cycle depends on close proximity to water. As larvae, they spend their developmental years in the stomachs of aquatic copa pods that try to

eat them. It isn't until they're consumed by larger animals e g. Humans that they can bust through our stomach lining and develop into adulthood while taking residents just under our skin. However, once the alt worm has set up camp under our skin. How does it get larvae back out into the world to begin the cycle again? If I remember correctly, the best cure for this disease is

a simple stick with a notch at the end. The worm's tail is inserted in the notch and spooled out of the patient, much like a noodle being twirled into a fork. Of course, one can use a coffee filter to remove copa pods from drinking water, preventing infection altogether. Thanks for making such an informative and entertaining podcast. Sincerely, Stephen PS. Rob is right. Rabies is effectively one fatal

if not vaccinated against before symptoms come on. However, there is one case of rabies being cured by a procedure called the Milwaukee Protocol. It seemed to have been a fluke, though, but it's an interesting enough topic to read about when you get the time. Well, Stephen, thank you for the message.

Actually did look into this into the Milwaukee Protocol, and I found an explanation in a paper called Failure of the Milwaukee Protocol and a Child with Rabies, published in Clinical Infectious Diseases in two thousand eleven by Angela Arum Burrow. At all. So this paper is looking at rabies encephalitis, and this is the phase of Raby's infection where the

virus has reached the central nervous system. Now, remember the normal courses that you're probably bitten by an infected animals, say somewhere in the body, maybe on the hand, and then viral particles from the saliva of that animal get into your muscle tissue, they infect nerve cells, and then they climb gradually up the nerve pathways until they finally reached the spinal cord in the brain. Now, remember that

Rabies typically has a long incubation period. There can potentially be months between the initial exposure and the onset of symptoms with encephalitis. Rabies encephalitis may in fact be one of the worst and most deadly diseases you could imagine, and but it is pretty much entirely preventable if you seek treatment immediately after you get bitten or otherwise exposed. And the treatment is referred to in the literature as

post exposure prophylaxis or PEP. And in fact, we've got some more listener mail coming up in a bit with direct experience with PEP. But anyway, the authors of this paper from two thousand eleven right that before two thousand four, there were only five documented cases of anyone ever surviving rabies and sephalitis, and all five of them were people who received some form of PEP, though they ended up reaching the encephalitis phase because the prophylaxis was maybe incomplete

or late. But in the year two thousand four, some doctors reported the first ever survival of rabies and sephalitis without any PEP. This was in a child who had received what they called the Milwaukee Protocol, which is a combination h that they describe the following way. They say, it's quote therapeutic coma, anti viral therapy, cerebral vaseo spasm management,

and avoidance of immunization. Now, unfortunately, it looks to me like attempts to reproduce this outcome in other patients have all failed, including in the case documented in this two thousand eleven paper. They tried the Milwaukee protocol, it didn't work.

So it's possible that, as Stephen says, the time it looked like it worked in two thousand four, was some kind of outlier or some kind of fluke and and not a demonstration of any underlying usefulness in the therapy um and I've actually seen at least one more recent paper just discouraging its use altogether. We've got another message from Nate concerning treatment for rabies, and it goes like this,

Robert and Joe love the show. I was listening to your episodes on Thurst and thought i'd share my experience with the rabies vaccine. Back in I had contact with a bat that found its way into my condo. I got it out of my place and wasn't too worried about it until my friend described how terrible rabies really is. I'm relatively certain that I wasn't bitten, but I went to the doctor anyway. The doctor decided to give me

the vaccine to be cautious. The vaccine consisted of one shot in each arm and one shot in each thigh, followed by three more follow up visits with one shot in the arm. The first few days after the initial dose, I started to feel some flu like symptoms. Flu like symptoms also happened to be the early signs of rabies. At that time, I wasn't aware that vaccine side effects are relatively common, so that resulted in a pretty stressful couple of days. However, after the side effects went away,

everything was good. Then my bill arrived for the vaccine. The pre insurance cost listed on the bill was thirty seven thousand dollars. It was so unbelievable that seven shots could be listed anywhere near that price. Luckily, my insurance covered most of it, but I still ended up paying about sevent dollars for the vaccines. I'm sure this pales in comparison with some other drugs, such as treatments for cancer and HIV and so forth, but it was pretty

mind blowing how expensive it was. It's not the wildest story, but just thought i'd share. You guys have a great show. Thanks for all the entertainment over the last few years. Nate, Well, Nate, I'm I'm glad to hear you all right now. I'm I'm very glad in any case, that you didn't get rabies and cephalitis and uh. And obviously it's good that you had health insurance, but that that is an astonishing bill.

I actually looked into this topic a bit, and I found an article exploring exactly this question, like why is rabies prophylaxis so expensive and why does the cost of it very so much so. This was an article called why a simple life saving raby shot can cost ten thousand dollars in America published in vox In by the healthcare reporter Sarah Cliff. I think she's at the New York Times now, but I've read a number of her articles about health healthcare in the US and uh and

they're good. But in this article, so the background is that apparently there are just a lot of cases in the US where people end up in medical debt after a possible rabies exposure. And the article starts with the story of a college student who literally had a bat fly into her mouth while she was trying to shoot it out of her apartment. Uh. So she goes to an urgent care and there they describes what happened. They refer her to an emergency room for treatment. This was

somewhere in New Hampshire. And then in the end, the bills she got for the full treatment was over six thousand dollars. And somehow this is on the low end of the cost range for for rabies p EP in the United States. The article claims that many bills are in the range of ten thousand dollars which of course is enormous, but obviously nowhere near your UH pre insurance bill of thirty seven thousands. So I really don't know what makes the difference in your case, especially since US

healthcare costs are often rather opaque UM. But according to Cliff, the main itemized cost of these treatments is usually a drug called immunoglobulin, which is designed to slow the spread of the rabies virus in its progression towards the central nervous system, which gives the body time to learn from the vaccine and fight the infection. And UH immunoglobulin is allegedly expensive to produce because it has to be manufactured using human blood, which has to be pre screened for disease.

So I guess it's a complicated process. But there are other major expenses for rabies treatment, sometimes because you have to go for multiple follow up visits and so there can be these hospital facility fees which get charged to people for showing up in the emergency room or at the clinic multiple times. But based on what this article describes it, it just seems like, you know, it's a say situation where the patient is kind of in a bind, like if you have potentially been exposed to rabies, you

have to get the treatment. You really need these vaccines because they're extremely effective and untreated rabies is basically a hundred percent fatal, so you can't afford to just roll the dice and hope you won't get it. Uh. So it seems like drug manufacturers here have a lot of leeway in what they can charge and still sell plenty of the drugs. So apparently the same drug can have

wildly different prices depending on where you get it. Cliffs article compares costs of identical rabies drugs in the US and other countries, and the ones in the US are sometimes like six times more than what the same drug costs in the UK. Though obviously in the UK, uh, there's another difference, which is the government will cover the direct cost to the drug rather than the patient. Um. But anyway, to come back on this, though, that is a pretty unpleasant state of affairs that you can end

up with like a ten thousand dollar bill there. Uh, you shouldn't let that discourage you from seeking treatment if you think you might have been exposed to rabies, because again, untreated rabies always ends in death, and it's a horrible death. So if you think it's possible, you've got to get

to a doctor as soon as you can. But anyway, this whole story reminded me of something else I was reading about recently, which is a totally different but complementary approach to fighting the impact of rabies on on on human society. And this intervention is attempting to intervene before

infection occurs by vaccinating wild animals against rabies. So in the United States, most people who are exposed to the rabies virus apparently get it from domestic animals like cats and dogs, which in turn get infected through encounters with

wild animals like raccoons, skunks, bats, coyotes, and foxes. So at any given time, the vast majority of disease carriers are not humans or domestic animals, but wild animals um And so if you could cut down on the rates of an infection among wild animals, that would downstream cut down on the rates of infection and exposure among domestic animals and humans. So I was reading about a series of programs by the U. S Department of Agriculture, Animal

and Plant Health Inspection Service Wildlife Services. That's a lot of words to essentially seed the wilderness with bait containing oral rabies vaccine UH and note that this type of vaccine is not nearly as expensive as the UH the full human p EP course. But to read from the U. S d A website on this program, quote oral rabies vaccination or o r V bait is distributed to wildlife in targeted areas. This edible bait consists of a satchet

or plastic packet containing the raboral VRG rabies vaccine. To make the bait attractive to wildlife, the sachets containing the vaccine are sprinkled with fishmeal coating, or encased inside hard fish meal polymer blocks about the size of a matchbox. Each year, w S I guess it's Wildlife Services and cooperators distribute about six point five million bits in selected states to create a zone where raccoon rabies can be contained. And I think they've been doing programs like this since

the nineties. They claim that for every dollar spent on the wild r V program, and estimate of somewhere between four dollars and thirteen dollars are saved in costs associated with rabies transmission into into humans and domestic animals down the line, So that sounds like a great intervention. Okay. One last response to our episodes on thirst. This one comes from Kenny. Kenny says, Hi, Rob and Joe. I

really enjoyed the first two episodes on thirst. I particularly like the discussion around the neural and endocrine systems the body uses to maintain the osmolarity of our blood. Since you only had time to touch on this, I thought I would write in about the mechanism by which the kidneys helped to regulate blood volume and osmotic concentration. I know it's an odd thing to find mind blowing, but it's one of those topics I remember most clearly from

my biomedical science degree in the late nineties. Each kidney contains about a million structures called nephrons. The initial elements of the nephron filter the blood, then reabsorb everything you want to keep, like glucose, amino acids and much of the water. The clever part happens when the filtrate enters a structure called the loop of Henley and descends into the renal medulla deep within the kidney. The function of the loop is to create an osmo larity gradient within

the surrounding interstitial tissue. It does this through the active transport of sodium chloride, meaning salt and water. The osmotic concentration of blood is about three hundred milla osmals per leader, but the interstitial fluid in the medulla is extremely hypertonic, so very salty, and can be as high as twelve hundred mill osmoles per leader. Once through the ascending arm of the loop, the filtrate is again extremely dilute and can have an osmotic concentration as low as seventy two

a hundred when it enters the collecting duct. This duct passes straight down through the osmolarity gradient. If you are dehydrated, then anti diuretic hormone acts upon the collecting duct to make it permeable to water. As the filtrate descends through the osmolality gradient, more and more water diffuses through the vessel walls by osmosis, pulled through by the higher concentration

of salts in the surrounding tissue. The more dehydrated you are, the more permeable the collecting duct, and the more concentrated the resulting urine. So despite the extreme tonicity of our most concentrated urine. It is in fact slightly hypotonic compared to the interstitial environment it passed through. In fact, the collecting duct is permeable to urea, which some of which diffuses out of the duck's lower reaches and further increases

the osmilarity of the surrounding fluid. On the other hand, if you've drunk so much water that you squelch when you walk, a d H is almost absent, and that's anti diuretic hormone. A d H is almost absent, and the collecting duct becomes almost impermeable to water, which means that the filtrate will pass straight through as extremely dilute, almost colorless urine. The nature of the structure means that there is a hard limit to how concentrated humans can

make their urine. We're not as good at retaining water as mammo's more adapted to arid conditions. A camel has large numbers of long loops of hinley, which allows it to maintain a hypertonic environment in its renal medulla with a concentration of more than double that of a human. This means that the camel can produce exceptionally concentrated urine and retain water for longer. I was also fascinated by your discussion on the taste of water. I live in Scotland,

famous for rain mountains and deep locks. The water from our taps is so good, but we are rightly appalled by the sorry state of the stuff that comes out of the taps south of the border, I guess in England. My aunt lives in the south of England, where the geology is completely different, and I used to dread the tap water down there. It didn't exactly taste of farts, but it's deeply unpleasant and I never found it refreshing at all. The high levels of calcium and magnesium in

the water, especially around London, where the water is very hard. Indeed, I mean the dishwashers and washing machines can end up with serious limescale build ups. Anyway, that's more than enough for me. Thanks for all you do, Kenny, uh and then Kenny also includes a little cartoon mocking the taste of English tap water. Well, Kenny, thank you for the message, the the interesting anatomical notes, but also yeah, I traveled England with my wife Rachel a few years back. And

it was a great trip. Uh. England is a wonderful country with many treasures. But yes, I distinctly remember the tap water tasted so wrong. It it was like it had been steeped in a barrel full of chalk and discarded latex gloves. But no disrespect to England. Uh. You know,

London is a place of fractal delights. And while we were there, we also went down to the Jurassic Coast and walked around with the wild ammonite fossils um, which is just great and one of my favorite feelings is is finding a fossil in its original exposure setting in the outdoors before somebody removes it to a collection or a museum. Uh. And if you've never done that, the Jurassic Coast is great. It's got ammonites and things all

over there. But I also recommend I've mentioned this on the show before, but the the hikes they offer to the trilobite beds of the Burgess Shale in the Canadian Rockies. That's one of my all time favorite excursions. Just magical. Anyway, I think that is going to be it for today's episode of Listener Mail, but we will be back to talk to you again soon. Hey. If you're new to the show, once again, This is the Stuff to Blow

Your Mind podcast. This is listener Mail, which we do every Monday, but we do core science and culture episodes on Tuesdays and Thursdays. We do short form episodes on Wednesdays, and then on Fridays, Rob and I usually do a casual episode that we call Weird House Cinema where we just talk about a weird movie, usually a monster movie or something from one of the genres. Uh. If you're not subscribed, you can find us wherever you get your podcast.

Just look up the Stuff to Blow your Mind feed or go to stuff to Blow your Mind dot com. Big thanks as always to our wonderful audio producer Seth Nicholas Johnson. If you would like to get in touch with us to maybe have your message featured on a future listener Mail episode, or to suggest a topic for the show for one of our core episodes, or just to say hello, you can email us at contact at stuff to Blow your Mind dot com. Stuff to Blow

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