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- [00:00]
Samantha Yamin
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- [00:55]
Carolyn Elia
Mushrooms are weird. Some taste amazing in risotto and some shut down your organs and could kill you. Fungi rot wood. They can grow in walls and they can spread through your body if they get the chance. They move quietly and take over whatever they touch. You can breathe them in without realizing they have spores. They're in the ground, in the air, on your skin. And they feed on death. They break down flesh and bone. Well, everything. We use them to bake bread, brew beer, and make medicine. But they don't care about any of that because they've been around way longer than us and they'll be here long after. They don't need us, but we sure need them.
- [01:36]
Dr. Carolyn Elia
The fact that the world is warming and the differential between environmental temps and the temps that we hold in our own bodies decreasing, you know, is scary, right? Because it means that there's a little bit less of a jump that needs to be made if some environmental fungus is to adapt to a warm human host.
- [01:58]
Carolyn Elia
Dr. Carolyn Elia is a mycologist. She studies strange fungal parasites that can take control of insect brains for real. And if you've ever watched the first season of the Last of Us, that might sound a little familiar. And Dr. Elliot talks about what's fact and what's fiction when it comes to the fungal induced zombie apocalypse of the show. And then something even more microscopic than fungi that's brought us breakthroughs in medicine. The MRNA vaccine. It gives your cells instructions so your body learns how to fight on its own. We'll get into those details later. I'm Dr. Samantha Amin and this is Curiosity Weekly from Discovery. First, there's some new research you have to hear about that's basically a way to bend sound for private listening. Picture this. You're on a road trip with family or friends, and the car is hacked. No one agrees on the music, so everyone resorts to their own headphones. Now imagine that same scenario, but with a twist. Each person can listen to their stuff without headphones. No overlapping sounds. You can't hear anyone else's audio but your own. You get your own private listening experience. No wires and no conflicts. Just seamless sound. It sounds pretty futuristic, but it could become reality. A team from Penn State is researching what they call audible enclaves. They've developed a way for individuals to listen to audio privately without headphones, with other people around them not being able to hear it. I'm picturing James Bond at a gala, gathering intel. And instead of an earpiece, he has, well, nothing. But he can hear cue clear as day. The team on this project used ultrasonic waves to create acoustic enclaves. It's like a personal sound bubble where only the intended person hears the audio, and they bend sound to do it. Sound is just vibration. Like when your car speakers bump, they shake molecules in the air. That shaking travels through the air as a sound wave. When it hits your ear, it vibrates little hairs in your ear sound. But our ears can't catch everything. We only hear stuff in a certain range. That range is from about 20Hz to 20,000Hz. Anything higher is ultrasonic, and that's way too high pitched for us to hear. Like dog whistle level, like Mariah Carey level. The team at Penn State took a device that emits ultrasound waves and combined it with an acoustic metasurface. Basically a surface with tiny structures that bend the waves. They call it a self bending beam. So let me break this down. If you're talking about how the sound bends and travels, that's physics. If you're talking about the tools and tech they use to make it happen, that's electronics and engineering. This is a mix of both. The team used those metasurfaces to bend the waves, shaping the sound exactly how they wanted it. Then they took some measurements to see how well it worked. They placed microphones on a mannequin and around the room to capture where the sound waves went. Then they hit play. And by the way, it was Handel's Messiah streaming through the lab space. But only some of the microphones picked it up, and not everyone could hear it. The ultrasonic sound waves aren't audible on their own. But where two bending waves came together at the correct spot, the mannequin could hear it. Or rather, its microphones. Could they set it up so sound waves moved from behind the mannequin to the front. Voila. An audible enclave was created. There's a lot you could do with this. Cars, the subway, concerts, public speaking, events at the beach, the gym. The opportunities and places you do this are endless. Right now, the researchers can only transfer the sound around a meter away, but they're working to increase distance and volume while also conducting tests to ensure the sound stays at a level safe for human ears. They pulled this off using tech we already have. Now we're talking about a whole new era of private listening. You can blast the Wicked soundtrack on repeat, and then your partner can listen to whatever it is they listen to. No arguments, no eye rolls, just peace.
- [06:11]
Samantha Yamin
Do you remember the brand that popped up while you were scrolling your social feed? No, but I bet you remember who sponsors your favorite podcast. That's because 74% of listeners recall the brands they hear when listening to podcasts. If you want your business to be top of mind, podcast advertising with Acast is the way to go. Book your campaign today by visiting go.acast.com ads.
- [06:42]
Carolyn Elia
Your brain is yours. Until it's not. Some parasites have the eerie ability to hijack a host's nervous system, turning them into mindless puppets, marionettes controlled for the parasite's own twisted survival. Dr. Carolyn Ellia @ Harvard has been studying one such parasite, a fungus that takes over fruit flies, compelling them to climb to high places before its lights out. As they make their final ascent, they unknowingly spread fungal spores to new victims, creating what are essentially zombie flies. It's not quite a zombie or fungal apocalypse. And while it's currently limited to insects, Dr. Elia's research could have bigger implications for how parasites manipulate brains, including our own. Her work is shedding light on neurological diseases and the hidden ways microbes interact, influence behavior. And if you've seen HBO's the Last of Us, you know, the idea of microbes quietly shaping minds might not be as far fetched as it seems. To help you separate fact from fiction, Dr. Carolyn Elia is the person to talk to. Dr. Carolyn Elia, thank you for being here. I want to jump right in. I read that you accidentally discovered insect zombies in your own backyard, and that experience was part of what inspired you to research the zombie fruit fly. Your research is so fascinating because it brings together multiple fields, fields that I think are quite different. How do you keep it all organized?
- [08:11]
Dr. Carolyn Elia
So like you're saying, this is an extremely sort of interdisciplinary thing to tackle. So the way that I've started my lab is to sort of bring in people from different disciplines to try and form this community of folks that probably you wouldn't necessarily see in the same group, but that can contribute to looking at different parts of the problem. People that are on the microbiology side and people that are on the neurobiology side. And then there's a whole other aspect of this system which I'm really fascinated by, which is the fact that flies only die at specific times of day. What, there's like a circadian. Yeah, there's a circadian aspect to it.
- [08:51]
Carolyn Elia
I did not know that. So they're just swarming around and then you'll just see a bunch drop.
- [08:59]
Dr. Carolyn Elia
Well, let me tell you about the life cycle because it's really cool. The fungus infects flies by ejecting infectious spores from a previously killed host. So those fly go pew, pew, pew into the environment and land on a susceptible host. They'll just land on the skin. And once they do so, through factors that we don't yet understand, they can somehow recognize sort of where they are. And they form a what we call a germ tube. So they form basically a liken it to a crazy straw that punches through the fly's cuticle and it transports fungal cell into the fly's blood. And the fly has an open circulatory system. So the blood is not constrained in arteries and capillaries, etc. It's just bathing all of the organs. The fungus gets inside and then it does something very, quote unquote sneaky, which is it goes after a tissue that the fly doesn't need to be alive. So this is called the fat body. And it's a storage tissue for extra nutrients. It also has some immune function. If the fly is well fed, it will have lots of fat body, and if it's starved, it will have less fat body. And so it's kind of this flexible organ, unlike, let's say your gut. And so it starts eating this tissue. But early on, some fungal cells transit and we don't know how, but somehow they get into the brain inside the brain. They're just hanging out in there. So we have two populations of fungal cells, one that's in the brain, one that's in the fly's body cavity. And the cells in the body cavity go to town. They eat that fat body tissue, they divide, they basically turn the fly into a sack of fungus. And then there must be some signal which we're trying to figure out what it is. Some Signal that tells the fungus, hey, this host is no longer good for you. You need to get out. When that signal occurs, then the fungus goes through a series of morphological changes. It puts on a cell wall which it had actually gotten rid of when it came into the fly. And that's super weird. It puts on a cell wall and it triggers a series of behavioral changes in the host. And these behavioral changes all serve to position the fly that's soon going to be dead in this ideal way. So the fungus can then erupt out of it, shoot spores into the environment and start this whole crazy cycle again. So the behaviors that the fungus elicits are it makes the fly climb. So like a wall, a stick, a blade of grass, whatever's nearby. And then the fly will stop walking. And the fly extends its proboscis and gets adhered via what we now know are fungal secretions that come out of the flies proboscis like a glue sticking the fly in place. So if even if it dies, it's not going to fall down because it's stuck by its mouth parts. Then lastly, the fungus makes the fly move its wings up and away from its back so they kind of stick up. And this was what I had noticed in my bait. And then they die in position. And after the fly dies, the fungus then rose back out through the fly skin. And these beautiful bands are gorgeous. I cannot get enough of looking at them under the microscope. That form these spore launching structures that then kick spores out into the environment. I glossed over the fact that this always happens at the same time of day. I forgot about that. Yes. That was what led us into this whole conversation. Yeah. So the fungus only secures this exit program, let's say at sunset. Like it's only going to cause the fly to perform this climbing behavior, to stick out its mouthparts to put up its wings and die. Always happens at sunset. So reliable. Like we literally set our clock and like our experiments around this timing we had early on in starting the lab, we had a huge discussion around sort of what time do we want sunset to be in the lab to kind of facilitate experiments. Like it's. Yeah, it's.
- [12:54]
Carolyn Elia
Oh, because you can set it artificially.
- [12:56]
Dr. Carolyn Elia
You can, yeah. You can tell? Basically. Yeah. So we set it so it's like right before lunch. So you go to lunch, you come back and you have dead flies that you can collect.
- [13:03]
Carolyn Elia
Yeah, I love that. You're like, okay, we want to time it with lunch. We'll all go and then we'll come back. They'll Be dead. We do our experiment.
- [13:12]
Dr. Carolyn Elia
Exactly.
- [13:12]
Carolyn Elia
Yeah.
- [13:13]
Dr. Carolyn Elia
But it was like a thing that we had to sit down and talk about.
- [13:16]
Carolyn Elia
That's amazing. It's so cool. One of the parts that I have the most curiosity about is the fungus specifically manipulating behavior. Because I've always wondered, how is that happening? How is a fungus able to, what, integrate into neural circuits or affect certain receptors in the brain? Like, what do you know about the mechanism of how something like a fungus can manipulate something as complex as a behavior?
- [13:40]
Dr. Carolyn Elia
Yeah, so this is work that I did as a postdoc was trying to figure out how that climbing behavior gets elicited by the fungus. To understand this, I developed this behavioral assay that allows us to actually sort of measure and quantify this. We call it summoning behavior, which we had been calling this behavior summiting for a century. But no one had actually seen that summoning in progress. They had just seen that sort of after effects of, oh, this insect is dead and it's stuck to in an elevated position, therefore it must have climbed up there to get there. But we didn't actually know sort of what that behavior looked like. So the first thing that I needed to do sort of to try and tackle this was actually have a way to figure out what is this behavior and to have some way to measure it. That's what I set up at the beginning of my postdoc. And then using fruit fly's amazing genetic toolkit, then I ran a massive screen to try and find neural circuit components, genes that were important for allowing this behavior to go. There's a subset of neurons that are in a conserved region of the fly's brain that are responsible for triggering the release of hormones. When you silence these neurons, you get very poor submitting behavior. It turns out in later experiments that we did, looking at where the fungus is distributed within the brain, which I told you, the fungus gets in there early. And initially I thought it's probably just sort of randomly distributed in there like polka dots. But it turns out that the fungus actually preferentially sits right down next to the processes that these neurons are projecting. And so it's kind of in the right place, the right time in order to chemically or even physically interact with these neurons to give rise to behaviors. So we still. There's a ton of questions open, like, why is the fungus actually, you know, how is it talking, quote unquote, to the neurons? Like, what kinds of chemicals is it producing? What on the neurons is receiving those messages? We don't know. And that's all subject of research for my current group.
- [15:58]
Carolyn Elia
This is the kind of stuff that just makes you think evolution is wild. But let's talk about the Last of us. With the show blowing up the way it has, what effect did it have on public interest in your research? Like, how did this help you work with public fears and misconceptions about the work that you do?
- [16:19]
Dr. Carolyn Elia
It's definitely brought a huge amount of interest to, I guess, specifically like zombie pathogens. But I think what it's done more generally for just this idea that, you know, we've kind of not thought about fungi as pathogens. You know, it's all bacteria and viruses. Right. But fungi are the scary ones because those are the ones that you do not want to be pathogenic. Right. Because they're so much like us. They're very hard to specifically target and kill. This is really sort of brought to the fore discussions around the fact that there are really scary fungal infections out there. They mostly impact people with compromised immune systems, but they have evolved to be able to tolerate higher body temperatures, which is something that the beginning of the Last of Us talks about. Right. As a barrier to actually infecting warm blooded animals. The fascination that people have with these systems and this idea that, you know, we could be sort of kicked out of the driver's seat of our own bodies. It's compelling and it helped to sort of buoy the interest in my work. And the timing couldn't have been better.
- [17:22]
Carolyn Elia
And the video game and show were inspired by a fungus referred to as Cordyceps. But you study Entomophthora. Did I do it? You did it. Yay. How many of these zombie fungi exist? Do we even. I'm sure we don't even know the exact number, but.
- [17:38]
Dr. Carolyn Elia
We don't know the exact number. But there's sort of like two hotspots in the fungal phylogeny where you find these guys. So there's the Hypocris, which is where it's an order where you have Cordyceps. We actually call Cordyceps ophiocordyceps now, at least the flavor that sort of inspired the show. But there's other species, so there's tons of different Ophiocordyceps species. There was also like a finding, like spiders infected with a zombie fungus. And then there's sort of this other group of fungi, which is where my fungus is from, the entomophthoralis. It's in a completely different phylum. Like I said, it's in this sort of region of the fungal phyllozinate. That is pretty poorly studied relative to the group that the opioid cordyceps comes from. So. But there's a ton of, you know, diversity in terms of, you know, who's infected and exactly what behaviors are driven. But there's also a lot of creepy commonalities, like the timing thing. That's pretty common. There are some sort of frequent behaviors that are elicited. One of them is the summoning behavior. But we're still. Still discovering them.
- [18:45]
Carolyn Elia
Now, there's a scene in the Last of Us, and no spoilers here because it's right at the beginning. Intro, Season 1, Episode 1. There are two scientists on a news show and one of them named Dr. Newman. He starts going off about fungal infections and their pathogenic behavior.
- [19:01]
Dr. Newman
Fungus, yes, that's the usual response. Fungi seem harmless enough.
- [19:08]
Carolyn Elia
So I want to break down with you some of what is talked about in this clip and get your perspective. Is it accurate? How likely is it? So let's break down some of what they say in this clip, because there.
- [19:20]
Dr. Newman
Are some fungi who seek not to kill, but to control.
- [19:24]
Carolyn Elia
He goes on to give some known examples of fungi impacting our brains, like how LSD comes from ergot and psilocybin.
- [19:31]
Dr. Newman
Also a fungus. Viruses can make us ill, but fungi can alter our very minds.
- [19:37]
Carolyn Elia
How much truth is there to that?
- [19:40]
Dr. Carolyn Elia
There is some truth in there, right? But there's also a lot of hyperbole. Creative license, let's say. Yeah, creative license or hyperbole. This idea that fungi seek to control, it implies agency and like intentionality. That's not how evolution works, guys. Things survive as change happens. It favors their continued survival and fitness. It spreads amongst the population. The fungus is not. It's not evil. It's not out to get us, right? It's just doing what it needs to get by.
- [20:11]
Carolyn Elia
Not you being a fungus apologist, don't.
- [20:14]
Dr. Carolyn Elia
Get me wrong, but from the broader perspective, it's all within its right to just survive. And then there's also viruses that can control our very minds. There's actually a lot of examples of viruses, especially impacting insects that can drive similar behavioral changes. I mean, and then in people, there's rabies, right? I mean, rabies drives pretty spectacular behavioral changes. So, you know, fungi are not alone in being able to, quote, unquote, control the mind. Again, coming back to this sort of idea of why and how evolution happens is if there's some advantage to be had. You know, if a mutation arises and it gives an organism an advantage, if that you know, mutation happens to result in being able to perturb a host's behavior in some way, then so be it. Right? It's not sort of like a sphere of sort of possibilities that mutation has to adhere to.
- [21:10]
Carolyn Elia
There's Another line from Dr. Newman that really piqued my interest.
- [21:14]
Dr. Newman
True, fungi cannot survive if its host's internal temperature is over 94 degrees. And currently, there are no reasons for fungi to evolve to be able to withstand higher temperatures. But what if that were to change? What if, for instance, the world was to get slightly warmer? Well, now there is reason to evolve.
- [21:35]
Carolyn Elia
I was watching, thinking, okay, the Earth is definitely getting warmer. So are we gonna see some of these mutations start to arise and fungi get more pathogenic and find a way to. I don't know. I spiraled.
- [21:49]
Dr. Carolyn Elia
Yeah. So again, I think there's a little bit of science fiction in here, but also some science fact. So this is when I started screaming at the TV, when he said 94 degrees, I was like, what are you talking about? Because that's just. I mean, saying that no fungus can survive past 94 degrees is just nonsensical. There's clearly fungi that are already causing infections that are growing at human body temperature. So 98.6 or thereabouts. So that's just patently false. But, yeah, I think historically, you know, fungi, they like it on the cooler side. They tend to be less thermal tolerant than, let's say, bacteria. The fact that the world is warming and the differential between environmental temps and the temps that we hold in our own bodies decreasing, you know, is scary. Right, because it means that there's a little bit less of a jump that needs to be made if some environmental fungus is to adapt to a warm human host.
- [22:50]
Carolyn Elia
Perhaps one of the most alarming things he says is, and there are no.
- [22:55]
Dr. Newman
Treatments for this, no preventatives, no cures. They don't exist. It's not even possible to make them.
- [23:03]
Carolyn Elia
So if that happens.
- [23:06]
Dr. Newman
We lose.
- [23:07]
Dr. Carolyn Elia
There certainly is a ton that needs to be done, and hopefully, in part, the last of us can get people on board with supporting, you know, creating fungal vaccines and developing more treatments to, you know, battle fungal infections. But there certainly are drugs out there that are used in order to treat fungal infections. So there's a group of drugs called azoles that are frequently used. But of course, you know, just like with bacteria that become resistant to antibiotics, there are now fungal strains that are cropping up that have resistance to these drugs. And so it's sort of not enough to just have one class of compound that we throw at every fungal infection because that is a recipe for running out of options.
- [23:51]
Carolyn Elia
Yeah, I would love to see fungal vaccines because again, I feel very scared about fungi. Dr. Carolyn Elia studies fungal pathogens and their host pathogen interactions within the fruit flow fly, also known as the zombie fly, at Harvard. And make sure to check out the second season of the Last of Us. It premieres April 13th on HBO and you can stream it on Max MRNA vaccines are a major advancement in modern medicine, but they've also been and continue to be the target of widespread misinformation. Understanding what they are and what they aren't helps cut through the noise. So let's break it all down. Vaccines are like teachers that train your body on how to fight off a virus or other pathogen. But with each type of vaccine, their coaching style is different. Some vaccines work by injecting a weak or inactive version of a virus into your body to trigger an immune response. But an MRNA vaccine doesn't. It gives your cells instructions to build their own practice opponent, kind of like a biological software update. These instructions come in the form of our body's favorite language, messenger RNA or mRNA. They instruct your cells to make a non infectious piece of the virus. For example, with COVID 19, the MRNA vaccine told the body how to produce its infamous spike protein, which is found on the surface of the virus that causes COVID 19. Remember all the hype about the spike protein and those graphics or emojis that look like a holiday ornament? You know, like clementines with cloves stuck in them. Once your immune system spots this spike protein, it goes into defense mode, learning to recognize and destroy it. That way, if you ever get exposed to the real virus, your body's already prepared to fight it off. That's why scientists were so interested in spike proteins. Now here's where the misinformation comes in. Some people have claimed that the MRNA in the vaccines can alter your DNA. That is completely false. The MRNA from the vaccine never enters the nucleus of your cells where DNA is stored. It just delivers its instructions to the cytoplasm where proteins are made and then it gets broken down. Kind of like a Snapchat message that self destructs after being read. Your DNA is totally untouched. Then there's the claim that scientists rush to make mRNA vaccines and that makes them unsafe. Also untrue mRNA vaccines have actually been in the works since the 90s. It wasn't some brand new idea that popped up in 2020. What changed was the global urgency which led to massive funding and accelerated trials. It was all hands on deck. They overlapped trial phases, enrolled participants quickly. They reviewed data in real time, cutting down the usual 5 to 15 year timeline to under a year. Even though the timeline was quick, no safety steps were skipped. By the time the first COVID 19 vaccines were approved, they had gone through the same rigorous testing as any other vaccine. And let's not forget the wildest claims like the one that MRNA vaccines contain microchips for government tracking. Let's be real, if someone wanted to track you, they'd use your smartphone. It would be much easier than an expensive high tech vaccine. At the end of the day, MRNA vaccines offer a safe and efficient way to protect against infectious diseases. And they're even being tested to prevent pancreatic cancer relapse. The data is clear. No matter what people say online, these vaccines have saved millions of lives for Warner Bros. Discovery Curiosity Weekly is produced by the team at Wheelhouse DNA. The senior producer and editorial correspondent is Theresa Carey. Our producer is Chiara Noni, our audio engineer is Nick Kharismi and head of Production for Wheelhouse DNA is Cassie Berman. And I'm Dr. Samantha Yamin. Thanks for listening. We all have that one friend whose opinion we trust on everything. For 63% of podcast listeners, that friend is their favorite podcast host. When Acast's podcasters endorse a brand, their audience listens and takes action. So if you want a recommendation that really sticks, put your brand in their hands. Book a host Red sponsorship today by visiting go.acast.com ads.