Welcome to Stuff to Blow Your Mind production of iHeartRadio.
Hey you welcome to Stuff to Blow Your Mind. My name is Robert Lamb.
And I'm Joe McCormack, and we're back with Part three of our series on cicadas. Now, if you haven't heard the first two parts yet, you probably want to go check those out first. This is one where we lay a lot of the groundwork in the earlier episodes. This series was a little strange because we broke right in the middle of it after part one for a break that we had for a couple of weeks, came back last week with Part two, and here we are with Part three.
Now.
In Part one, we talked about the basics of cicada biology, their branch of the insect family tree, their life cycle, reproduction, the sounds they make, their bodies and organs, and the evolution of long underground developmental periods and timed emergences in the minority of SCA, a species known as periodical cicadas, which we have here in North America. We just had a very interesting and rare kind of coinciding emergence of two relevant broods of thirteen and seventeen year cicadas this
year in twenty twenty four. The last time this coinciding emergence happened was like two hundred and twenty one years ago, so that's pretty cool. In part two of the series, we talked about the history of people being concerned with the question of whether periodical cicadas will bite them or sting them, or stuck out all their blood and leave them a thoroughly pumped frame. In the words of one New York Times article from the nineteenth century, they won't
do that. Don't worry, it's not going to happen. And then we talked about the work of the American entomologist Charles Lester Marlott, who did important research mapping and cataloging the different broods of periodical cicadas in eastern North America. And today we're back to talk about more cicada stuff right now.
Later on in this episode, we are going to be talking about a rather unique and by many standards, gnarly parasite of periodical cicadas, one that you may already be familiar with, even if it's like just surface level, because it's a rather outrageous example that sometimes breaks the surface of even late night coverage of science news. But before we're going to do that, we have a little cicada mythology, a little general cicada history to jump into here, right right.
So I came across an interesting fact, which is that cicadas are featured in one of Plato's dialogues, one that I've read before, and I had no memory of this being a part of the discussion at all. And this dialogue includes a mythological origin story for cicadas. So the dialogue in question is Plato's dialogue The Feedress, and it's a story told by Socrates. So Fedris is a very famous dialogue of Plato. A lot of people read it
in school. It covers a wide range of topics art, love, madness, reason, rhetoric, etc. It's the source of that famous chariot analogy where Socrates describes the soul as a chariot pulled by two horses with very different temperaments, each representing different forms of passion and instinct within human nature. And then the charioteer is sort of the reasoning part of the soul that must tame the two horses and steer them together on the path of truth and righteousness. Even though they want to
go in different directions on their own. But anyway, the story of the cicadas is not part of the Chariot analogy. It comes partially due to the setting of the dialogue. So in this dialogue, Socrates and this other guy, Feedris are outside the city of Athens, and it is said that they're sitting on the banks of a stream having a good old philosophical conversation, and in the background cicadas
are singing. They make reference to this a couple of times in the dialogue, and then Socrates starts imagining that if he and Fedris were not doing what they're doing, not having a philosophical conversation, but we're instead just lying by the river listening to the cicada song, he says that the cicadas would have a right to laugh at
them for being lazy and unvirtuous. But since the cicadas know that Socrates and Fedris are instead discoursing on philosophy, trying to get to the truth, and not being just lulled to sleep by their song, he says quote, they may perhaps, out of respect, give us of the gifts which they receive from the gods, that they may impart them to men, And then Fedris says, what gifts are you talking about? What gifts to cicadas have to give two men from the gods? And here I'm going to
read socrates response. This is the Benjamin Joet translation orig generally renders the name of the insect here as grasshoppers. But it seems to me generally agreed that this story is referring to cicadas. So I've gone through the passage and replace the word grasshopper with cicada. Excellent, Socrates says, A lover of music like yourself ought surely to have heard the story of the cicadas, who are said to have been human beings in an age before the muses.
And when the muses came and song appeared, they were ravished with delight and singing, always never thought of eating and drinking, until at last, in their forgetfulness, they died. And now they live again in the cicadas. And this is the return which the Muses make to them. They neither hunger nor thirst, but from the hour of their birth are always singing and never eating or drinking. And when they die, they go and inform the Muses in heaven,
who honors them on earth. They win the love of terpsickery for the dancers by their report of them, of Erato by the lovers, and of the other muses, for those who do them honor according to the several ways of honoring them, of Calliope, the eldest muse, and of Urania, who is next to her, for the philosophers, of whose music the cicadas make report to them. For these are the muses who are chiefly concerned with heaven and thought divine as well as human, and they have the sweetest
utterance for many reasons. Then we ought always to talk and not to sleep at mid day. So cicadas, according to this story, were humans before the time the muses came into being. And when the muses came to exist, they brought with them music. They brought song, and then the pre muse humans were so enraptured by the invention of music that they entertained themselves to death. They listened to music without eating or drinking until they just died.
And I guess made me to made music. Listen to music, it's all song and dance, until they just straight up died.
This is why you have concessions.
Yeah, exactly right, Yeah, but then but then the muses allow them to live again as cicadas and to sort of to be snitches for the muses, you know, to be the muse's earthly surveillance team, to kind of like hang out down here and spy on people and see who's honoring the muses properly and who is not honoring them.
And I was thinking about this and how it seems like it's kind of interesting to me to see how norms of moral and intellectual virtue are kind of different in our culture versus what Socrates is proposing here, because it seems like Socrates is talking like it's just rather obvious that sitting silently in nature, maybe falling asleep by a river, listening to the insects vocalized, is something akin
to a vice. At the very least. It's like intellectually lazy and not worthy behavior in the view of the intellectual muses like Calliope and Urania, who are muses of things like philosophy and eloquence and astronomy and stuff, you know, the muses of learning. And it's thought that these muses would certainly see it as better for people to be
engaged in philosophical argumentation. And this is to the extent that in the comment right before this selection, when Socrates is talking about, like, you know, he's first talking about the cicadas looking at them and judging what they're doing. Socrates says, quote, but if they see us discoursing like Odysseus, sailing past them, deaf to their siren voices, they may, perhaps, out of respect, give us of the gifts which they receive from the gods, that they may impart them to
men okes. I read the last part of that.
Yeah, all right, So the cicadas are singing, they're busy, enraptured by song, and if we're not living our lives to like full creative musical extent that we could, then they are going to shame us, and they're going to laugh at us. But if we're busy talking, having philosophical discussions, then they might just give us a little gift here and there.
Right, they'll go tell the muses that we've been good.
Yeah, we'll get a boon, Okay, okay.
But it's interesting that kind of difference in expectations because I think among I don't know, probably a lot of people sitting listening to this podcast right now, a lot of us today, I think probably think that sitting quietly in nature and listening to the bugs, sitting by a river, maybe dozing off is an activity that would be more associated with like virtue and seriousness and discipline and so forth, things like that today, And I don't think that would
be widely seen as like a less intellectually serious type of activity than arguing about the nature of reality and a philosophical discourse. It seems like, you know, every yahoo an out there wants to argue about what's true. You know.
Yeah, you can imagine like Socrates busting into my new yoga class that I go to and saying, why aren't you talking about philosophy? What are you doing laying about doing stretches, being in the now? Stop it?
So, I don't know, maybe our norms today extend from the idea that like, there are access to easier entertainments than like listening to the cicadas or something, and so if you're like really intellectually lazy, you're like watching TV or something instead of, maybe to the ancient Greek sitting and listening to the cicadas and dozing off by the river. That's the equivalent of watching TV or something.
I don't know, Yeah, I mean it also sounds like he's kind of shaming folks for being inactive and resting a little bit during like the hottest part of the day, you know. So I don't know, but I think you're right. Yeah, this does kind of turn a lot of our modern ideals and aspirations about everything from I mean really everything from midday rest and you know the idea of taking the siesta to doing like a mid day exercise, mid day yoga, meditation, or even just a mid afternoon nap. Yeah.
But I also like the idea that this mythology of cicada origins incorporates a couple of things. I mean, one is the interesting, like you know, the entertain themselves to death concept. It's not unique like that. There are other stories of similar kind of people who get so excited by some kind of activity that they forget to live.
And so there's that aspect. But also I like the idea of cicadas as surveillance devices, that they are down here spying on us for the gods, because it can sort of feel like that, right, like the way that you go into their space and you can't see them,
but you imagine they can see you. It often feels this way with various kinds of bugs that make sounds in the night, whether it's cicadas or not, because you might have that experience of, say, going into the woods at night and there bugs making sound, But then the bugs get quiet, so you realize they're aware of your presence and reacting to it, but you can't see any of them. So it does feel like a kind of surveillance situation.
Yeah. Yeah, you're literally bugged right, Oh yeah, yeah, And there is like we've been discussing with the cicadas like that, just that feel of them in their masses, like the rise and fall of their cadence. It it does have this very surreal feel to it. It feels like, like I say, I often think about it as just being like part of the midday heat. You know. It's it's something that's difficult for the human mind to sort of fathom as what it is, like, all these individual cicadas
making little sounds. It feels like something much bigger than us in many ways.
Yeah, almost like the gods are in on it. Yeah. But if there are some aspects of cicada biology that might make them feel like an envoy of the muses or some kind of you know, allied with the heavens. There are other ways in which you can learn things about cicadas that really make them like they were cursed by the devils, like if Hades has it out for them, Yeah.
Yeah, yeah, cursed by the gods or you know, who are we to question the strange creations the lonely perfection of the gods. I want to talk a bit about one very notable parasite of cicadas in general, but there's a lot of emphasis on the varieties that target are
periodical cicadas. So we've already discussed the unique life cycle of the periodical cicadas and some of the ideas concerning why they spend thirteen or seventeen years underground in this low metabolism subterranean larval form and then eventually erupt and engage in this noisy litter, producing a feast for predators
but also very vital reproductive cycle of their lives. And one of those one of the ideas behind this is that they do this in order to outmaneuver various predators and parasites that otherwise might sync up with their life cycle. Now We've already admitted though that this may seem to work in some cases, but periodical cicadas have not been able to outmaneuver everything. And of course we also discussed how like, basically the idea of everyone emerging at once
and reproducing also is to just overwhelm predators. They can't possibly eat everything, and any given species are going to live in some degree of equilibrium with its parasites, with its predators and so forth.
This actually would be a good place to mention something interesting I came across in research since the last episode, which is I was looking for more information about the actual direct evidence for predator saciation in periodicals, and again,
satiation is the evolutionary strategy we've been talking about. It's one hypothesized reason for these mass periodical emergencies, where the idea is, again there are more cicadas than all the predators that eat them can possibly eat all at the same time, So the eating capacity of the predators and also the parasitizing capacity of the parasitoids is overwhelmed. There's too much all at once, and thus each individual cicada's
chances of suffering from predation are much lower. So I was like, well, what is the actual evidence for predator saciation, and so I found an interesting study. It was won by Richard Carbond done in the journal Ecology in nineteen eighty two called Increased reproductive success at high densities and predator satiation for periodical Cicadas. In the study, the researchers combed over selected areas during periodical cicada emergencies and collected
cicada wings, which was an interesting strategy. Basically, they were trying to look at bird predation on cicadas and they discovered that wings are often discarded when birds eat cicadas, so bird chomps the cicada, the wings fall off, and so they collected wings in these areas to allow the researchers to form rough estimates of how many cicadas are eaten by birds within the area at a given time period.
And what the author here found was interesting. The number of wings increased its sites with more bird density, so cram more predators into a region, more cicadas get eaten, but the number of wings did not increase at sites with more cicada density, so more things to eat doesn't matter. Nothing more gets eaten. In other words, if you put more cicadas in the area, and the bird population remains the same. No additional cicadas get eaten by birds, because
the birds are already eating their fill. There's already more than they possibly can get to, and thus each end of jual cicada's chance of being eaten goes down. That's the predator satiation scenario. The predators are full. But of course the real danger in the bird predation scenario would be if the birds caught on to this in some way and increased their numbers to take advantage of this
massive amount of leftovers. Maybe if they had more offspring and increase their population density at the time when cicadas were available, or if more birds migrated to the area at the time when cicadas were available, or something like that. So if the number of predators goes up, the safety advantage for cicadas goes down. And this is another reason that it's hypothesized that the thirteen or seventeen year period
is helpful. The ideas this makes it harder to track with, like the predators can't sync up their migration or reproductive or whatever cycles to be in the right place at the right time to take advantage of all the cicada biomass.
So sorry for the digression, but I had discarded cicada wings on the brain, So that'll bring us back to you were saying that the cicadas are not able to outmaneuver everything, and there's one organism in particular that is a parasite that has adapted to periodical cicadas.
That's right. This organism is Masospora cicadia. And this is a fungal pathogen that was discovered by American mycologist and botanist Charles Horton Peck back in eighteen seventy nine, who is a pretty important figure in North American mycology around the turn of the twentieth century. I think like thousands of different species of fungus were described by him, North American fungo, fung gui and he was also the New York State Botanist from eighteen sixty seven through nineteen fifteen.
So I went back and I was reading Peck's original report on the fungus in question, back in eighteen seventy nine's thirty first Annual report on the New York State Museum of Natural History by the Regions of the University of the state of New York.
What state was that in?
Well, New York, of course. But the paper is quite readable, and it describes most of the key features of the parasitic infection of periodical cicadas, and does so redis succinctly. So I'm going to read a passage from it here. But basically he starts off by mentioning that fungal parasites of insects are known and are quite common. So this was,
in and of itself nothing new. And certainly, if you pay any attention to science news, you have run across various examples of those various fungal parasites that depend on insects, and in many cases, like you don't seem to alter their biology and or behavior. You know, puppet masters if you will.
Yeah, we've done episodes in the past about Ohiocordyceps fungus specifically praying on insects, and I don't know if this has overlapped with that or not, but.
There are some I think it it lines up in places though there are some mysteries that remain, and I think there's still you know, there's still certain mysteries that remain with with other examples of fungal parasites. We're still learning a lot. There's still some things that are more in the realm of hypothesis that sometimes maybe get picked up and carried into the mainstream press a little more settled than they actually are. We're still learning a lot.
At the time of this writing, though, this was a new one and it was based on some specimens that had been sent to Peck from New Jersey. So in this text he writes, the fungus develops itself in the abdomen of the insect and consists almost wholly of a mass of pale, yellowish or clay colored spores, which to the naked eye has the appearance of a lump of whitish clay. The insects attacked by it becomes sluggish and averse to flight, so that they can easily be taken
by hand. After a time, some of the posterior rings of the abdomen fall away, revealing the fungus within. Strange as it may seem, the insect may and sometimes does live for a time even in this condition. So that's some of like the basic observable aspects of this. And I don't believe I've ever looked at a cicada specimen with this scenario. I mean, I've you know, in the course of my life, I've I've nudged quite a few with my feet, you know, or or accidentally stepped on one.
But I don't know if I've noticed this before. But basically, if you look at the pictures and footage and so forth, you will find adult cicada specimens, so winged specimens that have they have a situation where their abdomen has seemingly like turned to like chalky clay. You know, It's almost like their abdomen has internally petrified and then begins to crumble, with the outer ridges falling away from it.
And yet the insect is at this point still alive, which is gross and weird to think about, right.
Yeah, yeah, And as as Pack pointed out, you know, there are many observ do say that they seem to be more sluggish. I'll get into a little bit about that in a bit. But then on the other hand, they can also seem very energetic. So there's a lot going on here. And again there seems to be a lot of investigation still ongoing in various hypotheses regarding exactly what's going on, and then there's certain things that are just unknowable. You know, we cannot know the mind of the cicada.
Yeah, it's just hard to imagine, like a mammal equivalent, Like if a human, like the low from your belly button down, that like is just gone, that fell off, and there's just like a big lump of white clay chalk kind of gunk sticking out of the bottom of your torso and you're still alive and moving around, but maybe sluggish.
Yeah, yeah, leaving a trail of spores behind you and occasionally rubbing spores against other humans and infecting them. So I looked to a couple of different recent sources about the organism in question. Rachel treisman Over at MPR covered M Cicadina earlier this month, providing a nice overview of
the organism. Essentially, it's still quite active and one of the reasons, of course, you know, we have these emergencies, these these two major broods, and so there are a lot of periodical cilicadas out there, and there's gonna be a certain amount of infected periodical circados to check out. So I'm gonna have to keep an eye open for these now. And certainly listeners write in if you find one.
But it's interesting that the chalky abdomen that we've been describing it does kind of match up with the name of the organism. So massospora essentially means spore grinder, alluding to the fact that it would almost seem that the hind parts of the cicada have been again petrified and then pulverized or like grated, you know, like parmesan cheese or something.
Oh not the not the shreds, but the dust. Yeah, using that side of the greater box. Yeah, you want the dusting, right, Yeah. So it's try some points out here. M. Cicadina employees is active host transmission, So the cicada again remains alive and active, though its behavior may be altered by the fungus, or i mean, the behavior seems to be altered by the fungus. Exactly how it's being altered, you know, if we're talking physically, chemically, so forth. There's
a lot of back and forth over that. But all of this does seem to serve to optimize the distribution of the spores. So let's break down the live cycle. And I'm also drawing on a specialized fungal parasite hijacks the Sexual Signals of periodical Cicadas by koli at All, published in scientific reports back in twenty eighteen. Okay, so remember the life cycle of the periodical cicada. So it
begins here with the emergence of those periodical cicadas. They're coming up through the ground and as this occurs, some of the individuals become infected with this this fungal parasite. Now, the exact number, estimates are maybe five percent of the population total according to Treisman, but the number can reach twenty to thirty percent in different areas. So you know, you might have a like a major hub, a major area where they're the higher.
Rate of infection. But overall it's thought that maybe this is like five percent of the periodical cicada population. Okay, so these are already these ones that are emerging and become infected as they emerge. More than that at a second. In a second, these are stage one infected cicadas, and they produce haploid condiospores that can infect other active adult cicadas. Later on in the emergence, the cicadas infected by these spores becomes stage two cicadas and stage two infected cicadas,
and they produce diploid resting spores. These spores fall to the ground where they can actually seemingly lay dormant in or on the soil for thirteen to seventeen years, though they can activate pretty much right away, but they're there on or in the soil, and they infect emerging nymphs.
Ah okay, So spores that can just lie in wait for thirteen or seventeen years get around the periodical adaptation in a way that the population of predatory animals could not. You can't have a big enough population of birds to eat all of the cicadas just waiting around for thirteen years for them to come back. They'd starve in the meantime. But if you're a spore, you can just sit there and wait.
That's right, like a little landmine, ready to go off and infect one of those nymphs when it begins emerging for the final period of the life cycle. So that's the basic cycle. But then there are the details of what the infection does. The major thing, of course, is
what we've already talked about. This is the distension and loss of these abdominal segments, which includes the genitalia in both sexes, So, in other words, turns the entire inside of the abdomen into one big mass of spores, it loses any of its reproductive organs, and then all of this becomes exposed as the outer abdomen eventually ruptures and begins to fall away, and they turn into crawling, flying spore crop dusters.
So they're just crawling around great in the spiky side of the box grade or just dusting everything.
That's right, that's right. And this is where the topic of behavioral adaptation comes into play. To what degree is the parasite also manipulating behavior of the infected cicada. So yeah, a lot of coverage points to this, but when you get into some of the papers, such as the one I just cited, there seems to be a lot more uncertainty because, on one hands, cooly I all point out some of the apparent changes in behavior may be brought on as much by physical changes due to the infection.
For instance, they cite that infected cicadas often remain more stationary, make shorter flights, and drag their abdomens when they want trailing spores. Of course, and these changes could in large part be brought on by the damage they've sustained via the infection. Again, they've they've they've sustained a lot of damage here. They're they're abdomen has been transformed into just a sport a crumbling spor sack with the flesh, you know,
crumbling off around it. And they also point out that stage ones tend to walk and trail more, while Stage twos tend to fly and spread. So, you know, I guess the idea here is Stage ones are trailing and around in you know, on branches and areas where other cicadas are going to gather, while the stage twos they're flying around because their spores are you know, mint if we we dare use that word to to to fall to the ground where they will be useful later on
when nymphs emerge. But they stressed that this could be behavioral manipulation as well. Uh So, here's where it gets even more interesting. This, according to Coolie at All quote, stage one massive spora infection, which produce spores that are spread directly to other adult cicadas, cause males to wingflick in response to the calls of other males with the same species specific timing used by sexually receptive magicicada females.
These novel wing flick responses are attractive to normal, uninfected males who repeatedly attempt to copulate with the disease males. So these copulations are going to be unfruitful, be it male female or male male matches, because remember the genitals are all destroyed anyway. But it results in a mimicry of receptive mates, and so they end up, you know, rubbing their abdomens together. At least, you know, you're getting those spores moved around, the scores spread, and that, at
least to the fungus is what matters. And in this the fungal pathogen acts as a sexually transmitted pathogen.
Okay, so this is an example of how it may be the fungus, as we've seen in other examples of a fungi that infect insects. Because remember, like the other example I mentioned the Ohio Cordyceps fungus which infects ants.
I think that's the one that causes them to you know, it makes them like climb up to the top of a you know, some overhanging thing, and they like glatch onto it, and then they grow these bodies out of like a spike out of their head or somewhere out of their bodies and rain down spores on the other
ants below. That's an example of what is thought to be a kind of behavior manipulation, and this looks more like a direct behavior manipulation, and not just the insects responding to changes in their body right.
But with one potential caveat when we get to the chemical aspect of what may or may not be going on. Okay, okay, so okay, So we have these stage ones, We have these males on their branches, twitching their wings like their females, attracting other males. Stage two infections, though, do not cause this behavior. And again the stress seems to be on these these stage two infected cicadas spreading these spores to the ground where they will in time infect emergent nymphs.
So this is where we get to the chemical aspect of it, and the idea that there's chemical manipulation going
on as well by the parasite. So as pointed out in Triisman's article, the fungus has also been found to produce a stimulant called cathinone a plant associated amphetamine in four infected cicada populations, and then elsewhere we have infected populations of annual cicadas which were found to contain the hallucinogen psilocybin, according to a study published in Fungal Ecology back in twenty nineteen.
Wait a minute, so it's this fungus is getting its hosts sort of caffeinated and on mushrooms.
Essentially, Yeah, there is. So one of the big caveats here is that, again, we can't know the mind of a cicada. Right, A lot of headlines that you know, you know, at least jokingly have some fun with the idea that the cicadas are high out of their minds. We don't really know if they're high, but we can't help. But but but look at these chemicals in these cicadas and wonder, like, what the purpose is here? What is it doing? And to what degree is it affecting behavior?
And there seems to be a strong case for.
That, right, I apologize for over anthropomorphizing by implication.
No no, no, no, But you're you're also onto the right track too. So I couldn't find as much about the psilossignment aspect and again, those are going to be annual cicadas and not periodicals. But there has been more hypothesized about the stimulants in the periodical cicadas, so some have speculated that these do in fact enhance cicada libidah or to some degree make this caya not particularly care
about the physical changes they're undergoing. But the other main interpretation is that that that cathinone the stimulant is what causes that rapid wing movement, So like, oh, like, why are they moving their wings rapidly and mimic and ultimately mimicking receptive females. It could be because they're just jacked up on this uh, this this particular stimulant in their bodies and it's causing the wing flapping, which then causes this additional behavioral change.
So it's possible the stimulant causes just sort of a nervous behavior, like a flexing kind of behavior, which happens to resemble mating signals, which attracts other males who hopefully will get infected by this fungus from the fungus's perspective.
That's right. Again, there's a lot there's a lot more to consider there, and there seems to be a lot of work still going on, and you know, ultimately this gate is getting high. We just don't know, But you might wonder about humans getting high, because, of course, both of these substances we mentioned, including psilocybin, of course, are
known for their effects in human beings. So you might wonder, well, could not a human just come along and eat a bunch of cathanone or psilocybin infected cicadas and then experience that the intended high. And we have to remember that cicadas themselves have long been on the menu for humans, so there's nothing out of bounds about eating cicadas, But what about these infected ones? Could you get high?
Okay?
Well, fortunately, there have been some papers that have already analyzed this question. We've had some experts weigh in on it. So one individual, there's a doctor David Shelter aka bug Doctor Dave or bug Doc Dave from Ohio State University, and he's already taken to the news cycle to get ahead of this informing everyone that, okay, first of all, one hundred to one hundred and fifty pound human being would have to eat about one hundred infected cicadas to
feel anything off of that cathinone in their systems. And if you weigh more than that, if you weigh more than one fifty, you're going to have to eat even more infected cicadas.
You know, far be it from me to demonize into myphaji. Nothing wrong with eating insects, But I don't know if you ate that many infected cicadas, I feel like you might just barf before you got to got to the same. I don't know, well, I don't even know what the exact effects of cathinone are supposed to be in a human. Would it be similar to other common stimulants like caffeine or something.
I was reading a little bit about other uses of it, and there are other ways that humans have long acquired it. It would be like a stimulant high. So that's another thing worth keeping in mind. It's like there are other ways out there to get this other than eating cicadas. And I also have seen it advise that when humans do eat cicadas, we tend to eat the ones that have just emerged from their shells, like these are the tastiest. These are the juiciest. I've heard them described as buttery.
The ones we're talking about the ones that are full of pathoogenic fungal spores. These look like they would even if you're not talking about eating a big lump of fungal spores, they're going to be like maybe crustier and crunchier and like just not as good.
Yeah. So so the ones that have just emerged, they're like the soft shell crabs of the insect world.
Yeah, I think that's that's that's probably an accurate comparison. Like, you want the soft shell It's okay this, you don't want the drier ones, the older ones, And that's not even counting in this big old lump of spores. And
I also found some additional info in this. Matt Cassen, an associate professor of forest pathology and mycology at West Virginia University, points out in a Carol Murphy Marcos article for The Guardian that, Okay, we do have people out there already trying this, trying to eat a bunch of cicadas to get that stimulant hit. But he cautions again he says, quote, there's always a risk in eating cicadas
pump filled with amphetamines. That was just one of a thousand compounds we found in the cicadas, and we don't know what those other compounds are capable of doing to humans. So I think all that sounds like a good reason to maybe pass on this particular high if you ask me, I mean, it's not going to make your butt crumble or anything. I mean, nobody's arguing that like these are. You know, like others have pointed out in some of these articles, you can pick up one of these infected
cicadas and look at it. You might want to wash your hands afterwards, but it's not like, oh, I might catch these spores like these are these spores are not for you. But on the other hand, I don't eat a hundred of them because I just aren't exactly sure what else is in there. Yeah, So in general, there's
a better use of your time. There are better ways to enjoy the cicadas, you know, listen to them, enjoy the ambiance, or in decide that this is essentially the muse is telling you you need to get deep and
talk about philosophy. I guess the other challenge worth pointing out here is, of course, again in general, we're talking something like five percent of the cicada population, So you're gonna have, you would have to do a fair amount of foraging to get anywhere anything like enough dead cicadas to eat for this particular ill advised experiment, I'd say have an espresso instead.
Did you find it? I wonder what do the natural predators think about the infected ones, so they have any preference for against do they care?
You know, I didn't see that address in any of the articles I was looking at. Yeah, you are predators avoiding the infected cicadas that maybe something will have to come back to if there's anything out there dealing with it.
Well, I asked, because I'm again not recommending people eat these things for the aforementioned reasons, But you know, I think about there are cases of certain certain things with fungal infections being considered especially good or a delicacy, at least by humans, and in some cases maybe preferred by some predatory animals. I think about like you know, wheedlcoche in maize and stuff like that.
Yeah, yeah, or certainly you could. This is not a one to one here, but you could talk about the fermented fruit being attractive to various mammal species. You know, It's like when food when prey undergo certain changes, it may be more desirable. So yeah, I'll have to look around a bit more and see if anyone's talking about this, but I did not, and at least initially come across a study that tackled it well.
Before we wrap up, there's one more thing I wanted to bring up today because I mentioned it in the
last episode. Was and it was the idea of other possible explanations for why periodical cicadas would have these long thirteen and seventeen year periods between synchronized emergencies, like what are the evolutionary pressures driving that, apart from the hype athesis that it that it's part of a kind of beefing up of the satiation strategy, the anti predator strategy, which does seem to be a dominant way of thinking about it. But there are questions about that kind of strategy.
And one is, for example, only a few species of the many many species of cicadas on Earth are periodical like this, And if it is, and you know, all these other annual cicadas from around the world are also preyed on by you know, lots of predators eat them, and so if this is such a a such a fruitful strategy, why don't more species exhibit it.
Yeah, that's a great point. And it also it didn't run across any speculation on this in the in the past, but we talked about how the mergence of periodical cicadas in North America is relatively speaking, a recent occurrence, a
recent development. It does make one wonder have there been other cases in the history of insects on Earth where some sort of insects species or another adapted to some sort of periodical lifestyle life cycle and it has just fallen away over time either those species went extinct, you know, or they evolved into stages they had to essentially become annual again, or something to that effect.
Yeah, yeah, I don't know. But I was looking into this question of like, Okay, well, what would other explanations be if it's not just this anti predator strategy or way to avoid parasitoids or predators adapting to your emergen cycle. And there seemed to be a few ideas floating around out there. One general class of explanations is that it is somehow just sort of a remnant of an adaptation
that was formed during the Pleistocene epoch. During there was a lot more glaciation in North America, and that these periods of cold unstable weather would move further and further south, and this pressure, the pressure of unpredictable cold weather, caused some cicadas to extend their underground periods and it provided
an evolutionary incentive. It rewarded them from coming out less often, developing these longer and longer periods underground, and then from that point on it was of course useful for these species to synchronize their emergencies to all come out at the same time. There was an incentive in favor of that.
Another hypothesis I've seen for specifically the thirteen and seventeen year timing of the emergencies is that once there were ancestral periodical populations in place, there would have been a biological incentive to avoid breeding with other populations that had a differently timed cycle, because this could lead to hybridization,
which would interfere with the periodicity adaptation. So like, in order to be effective as a periodically emerging species, you really want to be fully synchronized, like have all your population come out at once within the same place, so that you can take best advantage of predator satiation and so forth, and so it's possible there's a disincentive for thirteen and seventeen year populations to interbreed because that might
unsynchronize them. But I've also seen arguments sort of coming back against that, so it seems like to some extent, I think we alluded to this in the first episode. It still somewhat remains mysterious exactly why these thirteen and seventeen year time scales have been selected by evolution, but still leading hypotheses have something to do often with predator satiation.
Either it's too as we've said, to avoid predator and parasitoid adaptations matching the times of the emergence, or to avoid interbreeding or to h or maybe it is related to patterns that emerge during the ice age and have stuck around ever since.
Fascinating though anyway you look at it, and it's just one of the I think the great things about cicada is there's just so many interesting layers to them, from their their their basic anatomy and basic physiology, to these cycles, to then human interpretations of these cycles. Uh yeah, so much fun. And I guess we might be pressing on with another episode. I don't know, it's kind of TBD at this point. Will there be a Cicada Part four in this series? We're gonna have to to go back
to the notes and take a look. But I guess you know you'll find out in a couple of days.
Here see what emerges on Thursday.
That's right, all right, We're gonna goe and close out this episode, but hey, you have Cicada thoughts, Cicada observations right in. We would love to hear from you. Now that I think about it, I think we had a listener right in out the Bearside angle and nudged us forward on that, So you know, I don't recall who wrote in with that, but certainly that helped nudge us in this direction. But yeah, right in, we'd love to
hear from you. And just a reminder that Stuff to Blow your Mind is primarily a science and culture podcast, with core episodes on Tuesdays and Thursdays. On Mondays we do listener mail. Wednesdays, there's generally a short form episode, and then on Fridays we set aside most serious concerns to just talk about a weird film on Weird House Cinema.
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