What did the Jurassic world actually sound like? Using fossils and AI, scientists have reconstructed the calls of insects that lived alongside the dinosaurs. The result is the closest we’ve ever come to hearing prehistoric Earth.

Guests

Thorin Jonsson, senior researcher at the University of Graz specializing in bioacoustics. He is a lead author of the Jurassic soundscape study.

Charlie Woodrow, entomologist and a co-author of the Jurassic soundscape study.

Also Featured

Thomas Land, a zoologist and filmmaker who helped design the sound environment in the Netflix documentary The Dinosaurs.

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Transcript of Full Broadcast

The version of our broadcast available at the top of this page and via podcast apps is a condensed version of the full show. You can listen to the full, unedited broadcast here:

Part I

MEGHNA CHAKRABARTI: Thorin Jonsson is a senior researcher at the University of Graz in Austria, and he specializes in bioacoustics, and he helped create the soundscape you’re hearing right now, which sounds both familiar and not. So Thorin, first of all, welcome to On Point, and what exactly were we hearing just then?

THORIN JONSSON: Hi, Meghna. Thanks for having me. What we’re hearing just now were basically the sounds we recreated in our latest paper of bush crickets or katydids that lived 165 million years ago in a Jurassic forest.

CHAKRABARTI: So these sounds don’t actually exist anywhere on planet Earth right now.

JONSSON: No. We recreated them on the basis of some of our findings that we came out with in the last 10 years in our research.

CHAKRABARTI: Yeah, it’s quite remarkable to think that we’re hearing the best approximation that science has to offer right now about what the world sounded like in the time of the dinosaurs, essentially. So Thorin, take us back to the beginning of this project. What was the inspiration to try and acoustically put us back 165 million years ago?

JONSSON: Yeah, so it all started roughly 10 years ago when our Chinese colleagues came to us. … We were colleagues back in Bristol in the UK then. And they came to us and said, “Look, we have these really nicely pristinely preserved fossils of katydids, and we know all about the morphology and taxonomy and all that.

But you are the experts in modern-day bush cricket songs. Could you try and find out what they sounded like?” And that’s then what we did, basically.

CHAKRABARTI: And how did you do that?

JONSSON: Yeah, so these fossils that our Chinese colleagues had were really so well preserved that the wings of the animals were really well visible.

And on these wings were the sound production organs of bush crickets. So bush crickets produce their songs by rubbing their wings together. And on those wings are the sound production organs in the form of a file with little tiny teeth on it. And these fossils were so well preserved that we could really count these tiny teeth on them and do some measurements on them and compare this with the wings of living katydids.

And with that we could get an approximation of the frequency of the pitch that these animals would have sounded like.

CHAKRABARTI: Oh, okay. So Thorin, hang on here for one second because we have some isolated versions of these recreated … I was going to say Jurassic era, but I’m not … is 165 million years ago actually the Jurassic era, do, or do I have the wrong era?

JONSSON: No, it’s bang in the middle of the Jurassic era.

CHAKRABARTI: Okay. Great. So we have some isolated sounds from these Jurassic era recreations of the insects that would have made these sounds. So here’s one of them.

(SOUND PLAYS)

Okay, so Thorin, which one is this?

JONSSON: That I have to say off my head I actually can’t remember.

CHAKRABARTI: Okay.

JONSSON: Yeah. It’s one of the rather low frequency bush crickets that we created, which from the pitch sounds a lot like what you would have in crickets say nowadays.

CHAKRABARTI: In crickets.

Okay, so let me actually then get to a modern-day cricket sound. Just so for folks who don’t remember, here is what crickets today sound like.

(SOUND PLAYS)

CHAKRABARTI: Okay, so I can hear something of a similarity, but tell me a little bit more about how you took the specific fossil remnant, right? And you said you had counted the amount of teeth in the combs on the legs. Why don’t we first talk a little bit more about how modern-day insects actually make these sounds?

JONSSON: Yeah. So the modern-day crickets and bush crickets, they all make their songs which they actually create to attract females. It’s only the males that sing mostly. And they create them by rubbing their wings together. It’s a difference to grasshoppers. They rub their legs against the wings, but crickets and bush crickets just use their wings, rub them together, and on one side of the wing you have a hard area which is called the plectrum when you play the guitar.

And the other side has this row with the really tiny and hard teeth on it, and it gets rubbed together a bit like if you play a washboard.

CHAKRABARTI: And so that’s how they make the sounds today. And is it, do we know from the fossil record if the mechanism of sound making is the same in those Jurassic era insects?

JONSSON: Yeah, it actually really looked like not much has changed in the last 165 million years ago. So when we when we got these wings, we were actually quite surprised how nice and well-preserved those files with the teeth on it were and how regular and how they looked pretty much like wings and sound production organs of the animals today.

CHAKRABARTI: Okay. So let’s listen to two more calls from this Jurassic soundscape. The first one you’ll hear is a little bit slower paced, and then the second is a short burst of a similar call.

(SOUND PLAYS)

I would like to bring in Charlie Woodrow into the conversation now. He’s an entomologist and co-author of this Jurassic soundscape study, and he joins us from the UK. Charlie Woodrow, welcome to On Point.

CHARLIE WOODROW: Hi, Meghna. Thanks for having me.

CHAKRABARTI: Okay, for a person who has dedicated their professional life to the study of insects, what does it feel like to be able to hear, again, I’m going to say the closest recreation we have to prehistoric insects? What does it feel like to you?

WOODROW: Yeah, it’s incredibly exciting. From being a kid watching things like Jurassic Park and not even thinking about how accurate the sounds were in the background, to now understanding that we have the data and the methods to be able to actually produce those sounds.

We could make a director’s cut of Jurassic Park where it’s actually now fully accurate, and those kind of details I think are incredibly exciting to me.

CHAKRABARTI: Okay. I have a lot of questions for both of you about how we can claim accuracy a little bit later in the show. But tell me more Charlie, are there any morphological differences?

Thorin said that there aren’t, but it seems amazing to me that 165 million years of evolution has produced almost next to no significant changes in the bodies of modern-day, say, katydids versus ancient ones.

WOODROW: Yeah, this is in part because this mechanism of sound production is one of the oldest mechanisms of sound production in nature.

These insects have probably been communicating for 300 million years. And it just shows how efficient that system is. But there are small details between those species which do differ. So for example, the size of the wings or the spacing of those teeth. But what we were amazed to find is that a lot of that diversity was already around in the Jurassic.

CHAKRABARTI: Tell me more about that because I actually honestly had no idea. Because we all, when we think of Jurassic-era fauna, obviously, our minds go to the charismatic dinosaurs. How diverse do we know insect life was then?

WOODROW: Probably incredibly under-described in part because, these fossils are an exception in the fossil record.

Insects generally are small. They don’t fossilize very easily. But where you have regions like these deposits that our colleagues are studying in China, you can then get those amazing glimpses into the diversity of past ecosystems. But they are still a fraction of the diversity of insects that would have been around.

CHAKRABARTI: Were they, are they the same size? Are they large … let me say, were they larger than katydids, cicadas, grasshoppers now? Although I’m just describing three groups of insects that can vary quite a bit in size. But tell me more about like the size of the animals then.

WOODROW: Yeah, very similar kind of size range to the species we see today.

There were much bigger ones, of course. Thinking to even earlier back in the Carboniferous, there were these massive dragonflies as well, and other things we hear about. But there were many species which, you know, to the modern-day person you wouldn’t be able to tell the difference necessarily based on size alone.

So there was already an incredible diversity that’s mirrored in the size and shapes of these insects today as well.

CHAKRABARTI: Okay. Thorin, I understand that you actually went to China where these fossils were recovered. Is that right?

JONSSON: Yeah. Yeah as well, 10 years ago we went to, we were invited by our colleagues and were actually able to have a look at the fossil dig sites as well.

CHAKRABARTI: Yeah. And what was that like?

JONSSON: That was actually quite interesting. I’m a bioacoustician, not a paleontologist. It was really nice to see these dig sites, and they are all in Inner Mongolia in a region roughly 600 miles northeast of Beijing. And it’s a very rural area of China with farms all around, and then you had these just basically well shafts dug into the earth where they got the fossils out.

CHAKRABARTI: No, sorry, I didn’t mean to interrupt you. Continue.

JONSSON: No it was quite interesting to see that it was just these shafts where they got the fossils out and not open dig site, like open mining like we sometimes think about where fossils come from.

CHAKRABARTI: Now, Charlie, let me ask you.

Would it have been possible to recreate a soundscape for Jurassic era creatures that were anything other than insects? Because it sounds like you were relying on really what the external, the external shape or physiology of the insects are, not any sort of soft tissue internally.

WOODROW: Yeah, exactly. In order to reconstruct accurately the sound of any fossil, we need to know a lot about how that sound production organ works the size and morphology and how the structure relates to the sounds that they produce. And we use insects as a model for this because the morphology pretty much determines the sound they produce, and it’s incredibly well-preserved.

It would be really difficult to do this for a larynx or a syrinx of a bird or something, a soft tissue where those structures don’t fossilize in the three-dimensional structures by which they actually function.

Part II

CHAKRABARTI: So here’s another isolated call from the soundscape, and let’s listen to it.

Charlie, do you, can you help us identify which one this is supposed to be?

WOODROW: That is, like Thorin, I’m gonna struggle remembering which one it is actually. But they do all sound very similar, which is also interesting that these different species were also producing similar enough sounds that we can’t really distinguish them.

CHAKRABARTI: Okay. So let me ask you then do they sound, you wouldn’t have a tough time distinguishing sounds from insects today, right? Would you? Or do they also sound quite similar?

WOODROW: Yeah, some of them. I guess it depends how many years of your career you’ve spent to listening to them.

But of course many insects, katydids and crickets living today, we also cannot hear because they’re ultrasonic, and that’s kind of one of the big differences we found compared to our Jurassic study as well.

CHAKRABARTI: Oh, today they’re ultrasonic?

WOODROW: Yeah. In katydids alone, I think 70% of species use ultrasound to communicate.

CHAKRABARTI: Okay, so we’re gonna hold onto that thought for a second. But Thorin let me play one thing. Actually, let me see if I can find it. Nope, we’re gonna play that one a little bit later. Can you take me into more detail of how you went from having the fossil record, and then you also, we also have modern-day sounds from a whole variety of insects.

What was the process that you went through in order to then create the Jurassic era sound?

JONSSON: Yeah. Basically Fernando, who’s like another co-author, main author on the study, he’s been looking at katydid songs for, I don’t know, 25 years at least. He has this database of katydid songs from nowadays, and there are, like, hundreds of animals in there, and together with morphological measurements of the sound production organs.

And so once you have this information, you can basically plot it on a diagram and put a line through and say, “If you have a wing that’s that big with so and so many fi- teeth on it, then the frequency would’ve been this and this high.” And so we did the same measurements on our fossil wings and then plugged it into this diagram basically and said with these morphological details the frequency that these animals, the pitch that they would have created is,” I don’t know, say five kilohertz or so.

And we did that with all of our nine species from the Jurassic that we had.

CHAKRABARTI: Oh, interesting. Okay. So you basically, I can’t tell if it’s extrapolated or interpolated based on this big body of data you have on modern-day insects’ noises, yes?

JONSSON: Yeah, it was basically extrapolation from what we know from the modern-day insects, assuming that basically knowing from the morphology from our fossils that the sound production process in itself hasn’t actually changed for these 160 million years.

CHAKRABARTI: Okay. So Charlie, then help me understand a little bit more because I’m just trying to think of all the different ways that sound can be created from the same sort of physical structure, right? Okay even if I just put, if I put insects aside for a moment if I had a comb in my hand and I ran my thumb down the teeth of the comb, the sound that it would make very much depends on the speed at which I rub my thumb down the teeth of the comb, yes?

WOODROW: Yeah, absolutely. But it will also depend on the number of lines in that comb, the number of teeth in that comb, the spacing of them as well as the combination of how quick the thumb is moved across them. And also the size of the structures that that comb is attached to. You’re rubbing your thumb across those, but if you rub a guitar plectrum across them, you’re gonna get a slightly different sound, for example.

So it also depends on where those vibrations go and how they interact with other structures around them.

CHAKRABARTI: Okay, so this is interesting because then again, from modern insects, we know that the same insects can make a variety of noises with their same structures, right? Depending on the, as you said, all the variables.

Speed, which with the rubbing legs or wings together, maybe, I don’t know, maybe even just the surrounding acoustical properties of where they’re located. So for the Jurassic era fossils, you didn’t actually have access to that kind of information. So were you able to with any confidence say this structure, if it were vibrating at a certain frequency per second or per minute, would equal a mating sound?

Could you even go that far?

JONSSON: Yeah, absolutely. One of the nice things about this system is we know that they can only really produce one sound, and that again, the morphology of the wings really determines the sound they produce. But what we were able to do with these fossils is narrow down basically where that variation in sound, despite having the same mechanism, is coming from.

So for example, we see size variation across different species, and we know not just from insects but all animals that bigger animals tend to make lower-pitched sounds, and it’s the same in these insects. The bigger ones would have been slightly lower pitched. But we actually found a lot of the variation came from the morphology of that comb, if you like, that stridulatory file.

So we found lots of variation in the spacing of those teeth and the density of those, which would have affected the sounds produced.

CHAKRABARTI: I guess what I’m asking is in terms of the same creature, it could make a variety of noises. And I think, and correct me if I’m wrong, some of the sounds in the soundscape have been described as mating calls.

But how would you know that was a mating call?

WOODROW: Ah, I see. So basically, because in modern species they can typically only produce one sound. And we know that sound is for mating, then this is our best guess of what they’re using that sound for. And this is a very conserved function of the songs in crickets and katydids.

But of course, there are also other instances where they use those sounds for courtship or defense. But actually, the sounds they produce don’t really differ, it’s just the context.

CHAKRABARTI: It’s just the context. Okay. So a mating call would sound the same as a warning call?

JONSSON: Exactly. But what might differ is the warning call might be, have a higher rate of repetition or be louder because the insect is putting in more effort because it doesn’t want to be predated.

But the basic sound they produce, for example, during a closing or opening of the wings is very conserved.

CHAKRABARTI: Okay. So let’s listen to another modern-day sound. This is actually a black cricket, which makes noise with its wings. And here’s what that sounds like.

(SOUND PLAYS)

Now, I know everyone’s thinking, “That does not sound anything like a cricket.” But it’s very much slowed down?

JONSSON: Yeah. This is very much slowed down usually it would sound like one of the first cricket songs you played earlier, very high-pitched and this is just yeah, probably 40 to 50 times slowed down or so.

CHAKRABARTI: And so what does slowing down the sound tell you? Or what does it teach you?

JONSSON: If you would have songs from modern day katydids that sing in the ultrasound, we couldn’t hear anything. But if we slow the sounds down, then we shift those frequencies that we normally can’t hear into our audible range, and then we can make them audible for us to get an idea of what they could sound for us.

It’s basically just a bit of a tool to make things audible.

CHAKRABARTI: Okay, so let’s go back to the Jurassic soundscape, and this time, gentlemen, I will not ask you to identify which insect it might have been. But we will still enjoy the sound of it, so here it is.

So actually, Charlie, that high frequency whirring noise reminds me of a warm summer evening and tall grass to be perfectly honest. But it suddenly occurred to me, if Jurassic era insects are, were making these noises for warning, mating, what have you and they weren’t ultrasonic, it implies that other insects could hear them.

So they had ears, yes?

WOODROW: Yeah, absolutely. And it would have been the ears of the insects listening out for each other, but also the ears of predators, early mammals, other things, which would have been listening to those songs in order to predate those insects as well.

CHAKRABARTI: Do we have any idea of when hearing first became a sense in prehistoric life?

WOODROW: In terms of these insects, at least, it’s thought that hearing and singing actually co-evolved over 300 million years ago. And this is from a recent study which kind of mapped sound production and hearing across katydids and crickets, and their relatives and our best prediction was that actually these sounds were produced alongside the hearing organs for the function of attracting and finding a mate.

But in general, the hearing would have also been useful for those early insects to detect their predators.

CHAKRABARTI: Okay. So before 300 million years ago then, at least in the insect world, there was no hearing?

WOODROW: Probably very likely, yes. Although hearing organs in insects and many other animals came from organs for detecting vibrations, and so it was likely that before ears evolved, vibrations of predators and other things were used to detect noise in the environment.

CHAKRABARTI: Okay. And in modern-day insects, let’s say, again, katydids, grasshoppers, et cetera, what are their ears like? How do those, the ears function?

WOODROW: Yeah, they’re super cool. So in insects in general, they’ve evolved ears more than 20 times independently. Insects can evolve ears wherever they want basically.

But in crickets and katydids they actually have them in the front legs, so they have two eardrums in each leg. And what’s really cool is that they also have an ear canal which runs through the front leg, which delivers the sound to those eardrums. In grasshoppers and locusts and things it’s slightly different.

They have the ear on the side of their body towards the abdomen.

CHAKRABARTI: And correct me if I’m wrong, please, but I thought at least in some of these insects, the very sort of generalized function of the, quote-unquote, ear is not that different from human beings. Like you said, you described an ear drum, and is there, what, is there fluid behind the ear, the ear drum in insects also?

WOODROW: Yeah, so in most insects the anatomy of the ear, at least with an ear drum, is very simple. They’ll have an ear drum with a sensory cell attached to it and an air pocket behind it that allows that ear drum to vibrate. But quite uniquely in katydids they have ears that are pretty much identical at least in the steps of hearing to humans.

So they have an ear drum like us, and then we have connecting our ear drum to our cochlear a series of three small bones. They have this mechanism called a plate on the ear drum, which then connects that sound to a fluid-filled organ. And most incredibly, just like the human cochlear which filters out sound like a xylophone or piano into different frequencies, katydids have this tiny organ in their front legs which does exactly the same thing.

So the sounds that come into the ear are filtered to different areas or different receptors depending on their pitch.

CHAKRABARTI: Wow. Since we’ve been talking about katydids a lot, why don’t we just quickly listen to the sound of a modern katydid?

It’s actually genuinely delightful. So Thorin, we’ve talked about how you had all that data and you extrapolated based on the morphology of the fossils, what kind of frequency or sounds would come out of an ancient or prehistoric katydid. But I understand was AI also used in order to help create the soundscape?

JONSSON: I believe so, although I think that’s basically a question for Charlie because he was more involved in the recreation of the temporal aspect of that.

CHAKRABARTI: Yeah. Okay. Charlie, go ahead.

WOODROW: Yeah, sure. So I guess, to be clear, the kind of AI approach we used was not like ChatGPT where we just input a prompt and get a response. But it was a method of machine learning which has been around for a long time where we provide a lot of parameters which we think are important for our model. And we let the computer give us an unbiased assessment of the data to make predictions. So as Thorin mentioned, the way we used AI was basically to understand the repetition rate of those chirps.

So we can very accurately reconstruct a single chirp or syllable, so the opening or closing of the wings. But we don’t know how often those chirps are repeated through time. So we had two approaches. One was we could just make informed guesses or we can use this incredible database we have of modern species and we can take the length of the stridulatory file, the pitch of their song, and the duration of their song syllables and even actually how their songs are affected by temperature.

And we can train a machine learning algorithm to predict what is the likely repetition rates of those chirps based on what we know from living species. So it requires a lot of modern species and information, but then we let the model do it without us having to make assumptions.

Part III

CHAKRABARTI:  Now, what’s really fascinating is that this Jurassic soundscape has actually been somewhere where maybe you’ve seen it already or heard it, I should say, and that is Netflix. Tom Land is a zoologist and evo- evolutionary biologist, and he worked as a science researcher on the documentary series The Dinosaurs, which was produced by Steven Spielberg and narrated by Morgan Freeman.

Long before our time, they ruled a lost world. Witness the rise and the fall of nature’s greatest empire.

CHAKRABARTI: A little bit from the trailer for The Dinosaurs, and yeah, the dominant sound there was the dinosaurs themselves, or what production artists thought the dinosaurs sounded like. We’ll come back to that in a second. But usually in big productions like this, the sound design happens towards the tail end of the process.

But in this case, about a year before the series was finished, Tom Land began wondering whether its ancient landscapes could sound as carefully researched as they looked.

LAND: I was very keen, if we’re putting all of this detail, all of this energy and time into making the animals look as realistic as possible, their behavior as realistic as possible, why not take that the extra step?

Why not make the soundscapes, the world that they’re in, that extra layer of realistic?

CHAKRABARTI: So Tom connected with Charlie Woodrow, and they agreed to put some of the insects call, insect calls that you’ve been hearing, the ones created by Charlie and Thorin, they agreed to put those into the background of the documentary.

It’s one of those wonderful production details that you barely notice when you’re watching, but it makes the entire world feel more alive.

LAND: You are listening to the animals, literally the animals that dinosaurs would listen to, and that level of detail still gives me shivers, that we were able to use that.

CHAKRABARTI: Okay, so to the actual dinosaurs, though, what do you do? The fossil record can tell you about a dinosaur’s body size, its throat anatomy, the amount of air it might have moved, but obviously, as we talked earlier, those soft tissues, the vocal cords, cannot or almost never get preserved. So Tom looked for help from the dinosaurs’ modern-day descendants.

LAND: Dinosaurs aren’t extinct completely. Birds still exist. Birds are dinosaurs. So we were able to look at, looking at the basal birds, the paleognaths, as they’re called, emus, cassowaries, rheas, ostriches. Very, I don’t want to say basic noises, but very simple, loud, resonant noises can be inferred back with reptiles that were around at the time, the crocodilians.

CHAKRABARTI: So for each dinosaur species in the series, the team gathered relevant sounds from animals, birds, and some reptiles, as you heard, living today. They mixed those to make a dinosaur call, and here’s what they came up with for Dilophosaurus, a Jurassic predator.

LAND: It’s this female who’s looking for food, and hears this very, very haunting call drifting across the still waters of this swamp.

It’s a mating call, so it needs to have this element of flair and almost complexity to it. Looking at modern-day animals, we looked at the loon which has an incredibly haunting call.

We looked at Australian cassowaries because it gives this deep-throated, resonant, almost harmonizing with itself.

We’ve got the sandhill crane, the bulgar crane.

Pitch shifting it down, adding more layers to it so it seems like it’s not just, oh, we’re listening to a small bird somewhere, but actually this, you can hear it being a much larger animal.

You know you’re in trouble before you hear, before you see it. It’s always as though something from mythology has come about.

CHAKRABARTI: Tom went through a similar process for every dinosaur in the series, and he says having something as accurate as Charlie and Thorin’s research, even if it’s just in the background, raised the bar for what’s possible in future documentaries.

LAND: Their work genuinely gave the push forwards the sound project needed to being like, “Oh, we do have enough evidence for this. We can put this level of detail in. Let’s do it. Let’s go for it. We have it. Let’s do it.” So it was a landmark piece of information that they were able to get to us.

CHAKRABARTI: So that’s Tom Land, zoologist, evolutionary biologist, and filmmaker who worked on the Netflix documentary The Dinosaurs.

Charlie Woodrow, what was it like having your work be part of that series?

WOODROW: Yeah, it was incredible really. As Tom mentioned, it was a last-minute thing that came into place, and we were put into contact. And of course, I said yes. Yeah, no problem. It would be amazing to have those sounds featured.

And I tell my friends and family that I was a composer for Spielberg, so we’ll go with that.

CHAKRABARTI: And so I do have to ask you, as a scientist, I’m quite convinced by what both you and Thorin have said about, let’s say, the fidelity of the sounds in the Jurassic soundscape of the insects, right?

Given that the insects haven’t actually changed all that much. But Tom there had to use birds and reptiles for the sort of source sound for the dinosaurs, and birds, while related to dinosaurs, are wildly different. So there had to be some artistic license taken there, yes?

WOODROW: Yeah, absolutely. And a lot of people studying insects joke that paleontologists do like to stretch the realms of what we can infer from fossils and things. So you know, it’s amazing that they’ve been able to come this close and really engage the audience with these sounds of what the dinosaurs could have sounded like.

But at the end of the day, it’s super hard to know without the same level of detail as we get with those insects.

CHAKRABARTI: Yeah. Actually, Thorin, let me ask you this. You’re the bioacoustician here. Were there things that you learned from the process of recreating the Jurassic insects that could actually lead to more accurate recreations of other kinds of animals from prehistory?

JONSSON: Yeah, certainly. This is one thing that we now basically have a pipeline in a way, a framework where we can say we use this basic way of getting from the fossils to a potential song that they created in katydids, but there is no reason why this shouldn’t be able to be used in other insects also as well.

The only thing is that, say you have ants. There are a couple of ants nowadays that produce sounds or songs as well by rubbing hard parts of the shell of the cuticle against a row of pegs on another part of the cuticle. And if you find something like that in other fossils and compare this with what the animals sound nowadays, we could use very similar approaches to then find out the paleoacoustics of ants, say.

CHAKRABARTI: Did working on this project help you understand what’s actually always been a basic question that I’ve had? And some of these insects, in modern day, are really loud, and I’m always amazed by how, once I had a cicada accidentally fly into my condo, and they’re loud enough outside, but it was almost deafening inside the house.

Can you explain to us why they can make such a loud sound?

JONSSON: Yeah, and that’s actually part of my research and also what fascinates me in these insects is how can they be this loud? And in crickets and katydids, it’s mainly that the wings which create the songs and which vibrate and then amplify the vibrations that they produce, they are evolved to have resonance at exactly the same frequencies that they produce.

So it is a bit like they, like these insects carry their own violin body or something with them, so really evolved for the same frequencies.

CHAKRABARTI: Wait, so Charlie, does this mean that the bodies were involved to create sounds that traveled long distances as well?

WOODROW: The structure of the entire wing certainly would’ve been involved in producing the sound, but there are particular regions on the wing which as Thorin says, have a resonance which helps them amplify that sound.

And we know very well what kind of region on the wing that is.

CHAKRABARTI: Is that for sort of local amplification or maybe I’m just, I’m thinking that may, does that sound also travel farther or does it not?

WOODROW:  The amplification of the sound on the wing, it basically does, it does help the sound become louder, so it would help it travel a further distance.

CHAKRABARTI: Is that significant?

WOODROW: Yeah. In the case of attracting a mate, you want that sound to be as loud as possible. So if they didn’t have an area on the wing that matched the frequency of resonance with the frequency of the sound they produce, it would be a lot harder to attract mates over long distances.

CHAKRABARTI: Okay. So let’s talk for a moment about the other end of what we can hear. This is another call from the Jurassic soundscape, so let’s listen.

So very fast and high-pitched clicking noise, a little bit harder to hear. But Charlie, did you say a little earlier that perhaps some Jurassic era insects were actually communicating through ultrasonically?

WOODROW: Yeah, absolutely. So that insect we just heard is actually one of the ones that I can identify.

That is a species called Sigmaboilus peregrinus, and it was the highest pitch species … in this study. And actually what you’re hearing in that recording is just the, the lower energy parts of the call. The peak frequency that animal was producing, so the resonant frequency, would’ve been ultrasonic, so we wouldn’t be able to hear that, that song properly if we were in the Jurassic.

CHAKRABARTI: Is that new information to science?

WOODROW:  Yeah, it certainly pushes back the date of when we think ultrasound first emerged by almost 100 million years in this group.

CHAKRABARTI: And tell me why is that significant?

WOODROW:  Yeah in terms of insects and ultrasound, there’s been this long-standing hypothesis that insects didn’t really need to hear or produce ultrasound until about 50 million years ago when bats emerged and started to hunt them using echolocation.

Echolocation of the high-frequency pitch chirps produced by bats to find their prey. And it’s thought that as soon as bats appear, they’re using ultrasound and echolocation to predate insects. It’s beneficial to both hear and sing in that ultrasonic range as well. But this is 100 million years before bats emerged, and we already have ultrasound.

So what that tells us is that ultrasound did not evolve just for the detection of bats but for communication, finding your own channel to communicate or maybe listening to other predators which were using ultrasound.

CHAKRABARTI: Charlie, with all due respect, you’re really kinda keeping your cool here because you’re, like, almost underplaying what seems like a pretty significant finding based on the creation of this Jurassic era soundscape. Because if you’re saying that the theory beforehand was ultrasonic communication with insects was contemporaneously evolved because of bats, so mammals, but now there’s evidence, at least some evidence, that it could have happened 100 million years earlier, that seems amazing.

WOODROW: It’s pretty exciting.

CHAKRABARTI: Is that you being British or is it just you being a scientist, or both?

WOODROW: I think it’s good to be reserved with this. Fair enough. This is our current best prediction, but certainly what it tells us is the communication systems of these insects have been shaped by acoustic interactions with mammals for hundreds of million years before bats.

So early mammals before bats, and even before true mammals, there could have been acoustic interactions with insects, and that, I think, is one of the really cool findings.

CHAKRABARTI: Okay. I take your point about wanting to build a very substantial body of research before you get truly excited about anything, but since I’m not actually a scientist, I will have the sense of excitement for you.

Thorin, we’ve only got a couple of minutes left. I’m wondering what your sort of the most remarkable parts of this project were for you, and what kind of further questions you would, we wanna answer for the next time you use this technology for a bioacoustical body of research.

JONSSON: Yeah. So actually hearing the songs that then Charlie recreated with the help of the machine learning was pretty cool. And to actually then hear them and say, “Wow, this is what they could have sounded like,” was pretty amazing. But then the whole process I think for me personally it taught me a lot about that it is actually possible that we can get to this stage where we can say there was ultrasonic communication in 165 million years ago and that is cool.

This finding that, yeah, no one could have actually said that before and that is nice.

CHAKRABARTI: Yeah. I actually, I’m gonna give you also the last question here, because when we, in the popular mind, when we think about biology, obviously we think about cells and DNA and zoology, but what is it that studying bioacoustics can tell us that those other forms of scientific inquiry can’t?

JONSSON: So bioacoustics, in a way, looks at the mechanics of hearing and of signaling as well, and a lot of what that can tell us is how evolution works. So we can now say with our findings is that, oh, we have the mechanics of creating ultrasound in the Jurassic already.

And but then we can also say what is that, what can evolution basically do with this ultrasonic communication in 100 million years, in 165 million years? And that is really nice thing to look at.

This article was originally published on WBUR.org.