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SPEAKER 1: This is a production of Cornell University.
ANDREW BASS: And thanks to all of you for coming today. So all of us are part of a group of animals that are known as "vertebrates." And vertebrates also include many other mammals besides ourselves as well as fishes, amphibians, reptiles, and birds. Now, amongst all the living species of vertebrates, the largest group, in fact, are fishes.
Now, my ability to speak to you now and your ability to ask me questions depends upon your ability to vocalize, to produce sound. And most of us are familiar with sounds that other animals make during the summer, especially if you are able to live in a beautiful place like Ithaca or our surrounding communities. Because if you're out at night, what do you hear a lot? You hear frogs calling. Or if you're up early in the morning, you'll hear birds singing a lot.
And so those are animals we're really familiar with that are using sounds, and they use those sounds to communicate with each other just as I'm using sound right now to communicate to you. And what most people don't know, what both scientists and nonscientists alike are not aware of the fact that the majority of fishes are also probably using sound for purposes of social communication. And part of the reason that's a dramatic realization is because, again, nearly half of all living species out there are vertebrates, are, in fact fishes, so we're talking anywhere from [? 25,000 ?] to 40,000 different species of animals. And most of those are probably using sound.
Now, my ability to speak to you now depends upon various parts of my central nervous system. And so your central nervous system has two main parts to it that are known as your brain and your spinal cord. And many of you will be familiar with spinal cord and things that go with spinal cord injury. For example, you lose the ability to move.
And that ability depends on networks of cells in your nervous system that are known as "neurons." And those neurons are what provide all the timing that coordinates all of your muscles. So as you're taking notes now, you're relying upon the careful coordination of muscles in your hand and your fingers to be able to do that.
Well, at the same time, my ability to speak to you depends upon my being able to coordinate all the different muscles that are involved in speaking. There are muscles of my larynx, your voice box, that we use. I use the muscles of my tongue. I change the shape of my mouth as I speak to you.
Well, all animals use similar sets of muscles, in fact, to make sound. One of the great things about studying fish, however, is that they mainly use only one pair of muscles to make their sounds. And in the case of the fish that we've studied quite a bit and are the subject of this paper being published, they have a pair of muscles that are attached to a gas-filled swim bladder.
Now, most fish use their swim bladder to change their position in the water. But these fish have also adapted their swim bladder for making loud sounds. And they make these sounds-- these sounds will be different in differing social contexts. They mainly use them for purposes of reproduction.
So a male will produce a mate call at night to attract a female to his nest, or he'll produce another kind of call that's a territorial call to fend off intruders that might be trying to get into his nest and perhaps stealing eggs from his nest. And so fishes, like all other vertebrates including ourselves, make different kinds of sounds in different social contexts.
So here we have the largest group of living vertebrates. Most of them are probably using sound for purposes of social communication as we do ourselves. And then what this paper now reports is that superimposed upon that is if you look at the early development of the central nervous system, that is, the brain and spinal cord, what we've identified is a compartment in that developing nervous system where the most fundamental network of neurons is located that's essential to making these sounds.
And what we show through comparing that part of the nervous system to other animals, including primates, which include ourselves, humans, what we see is that all animals share the same compartment in the nervous system. So that-- why is this so important? Because, in fact, if this compartment were damaged in your brain, you would not speak again, period.
You can have damage to other parts of your nervous system, like individuals who have strokes, and they may lose the ability to speak for a period of time, but they can recover from that damage. But if you have damage to this part of the nervous system, then that ability is lost. It's similar to, again, a spinal cord injury. You lose the ability to control those neurons in your nervous system, and you're not able to walk.
So this most essential part of the central nervous system is what we propose is, in fact, shared by all animals including fishes. And fishes evolved hundreds of millions of years ago. And this result now results in the proposal that, in fact, the parts of the nervous system that are used for making sound in fact are very ancient and first evolved among fishes, if not earlier.
So I think that about sums up what we've done, and we have some examples of video clips that show you the animals that we study in particular, what they're doing. So you can get an idea of their behaviors and the different kinds of sounds that they make. And all of these videos that you're going to see, these are of what are called "midshipman fish."
So there's group of fishes out there they're known as "toad fishes." And they include midshipman fish and toad fish. Midshipmen fish are abundant along the West Coast of the United States and--
SPEAKER 2: You're--
ANDREW BASS: Oh, I'm sorry.
SPEAKER 2: No, that's a-- [INAUDIBLE].
ANDREW BASS: Can I take this off?
SPEAKER 2: [INAUDIBLE].
ANDREW BASS: Oh, OK, I'll just hold it. So you're going to see videos. I'll start over. You're going to see videos of what are known as "midshipman fish." And they are part of a larger group of fishes known as "toad fishes." And we've studied these fish for over 20 years, basically been studying them since I've been a faculty member here at Cornell.
And we know-- we have an incredible library of information on their social behavior and how they use sound for social communication. And we know intimate details about how their nervous system controls their ability to make these sounds. So what you're going to see is, during the summer, in fact, on a night like tonight, these animals will be in their nests in the intertidal zone along the coast, the Northwestern coast of the US.
And they're making calls. Males are going to be making calls to attract females, and they're making other calls to keep other males out of their nest. So we're fortunate. We're able to collect these animals from their nest sites.
And if you bring them into captivity and you keep them in [? aquaria ?] which mimic their natural surroundings, they'll do their thing in captivity. And so the videos you're going to see were-- they were made by someone in my laboratory by the name of Margaret Marchaterre. And she used video records along with audio recordings to be able to hear these animal sounds.
Now, these sounds are made underwater, so we can use an instrument known as a "hydrophone." A hydrophone is simply an underwater microphone. And the hydrophones we first used, fortunately, we actually got-- I got them from a colleague, Chris Clark, who's here at the Cornell Laboratory of Ornithology.
Cornell is a great place to be if you're interested in sound communication among animals. And the Cornell Laboratory of Ornithology-- I'm sure you're all aware of that-- has the largest repository of animal sounds in the world. And so it's a great place to do what we do for a lot of reasons, including the department I'm in.
SPEAKER 2: Why don't you stay right there?
ANDREW BASS: Oh.
SPEAKER 2: So that way, you have the microphone in front you.
ANDREW BASS: So, OK.
SPEAKER 2: [INAUDIBLE].
ANDREW BASS: Now, Aaron Rice, who's a-- or Aaron Rice is a postdoc in my lab who did the editing of the videos you're going to see. And so Aaron's going to play for you now, we're going to-- the first video you're going to see, you'll see these animals produce what is known as a "growl sound."
And so the setting is, here, we bring these animals to captivity, and we give them an artificial nest in which they can set up residency. And what you're going to see in this video, you'll see a male inside of his nest. And you're going to see other smaller fish swimming around the nest. And these are other smaller males that are trying to get inside of his nest.
And you'll see what happens, and then we can talk about it after it's over. So if we could play that first video, Aaron. So that's the male who owns that nest. That's his house. He owns that territory.
[FISH GROWLS]
So you saw another fish came into his vicinity. And he chases it away. And as he chases it away, he produces that growl sound.
[FISH GROWLS]
And that's one kind of call. That's a territorial call that he produces when chasing this animal away. Now, what you saw in that video, there was a-- actually, the hydrophone was sitting right above the nest there. It was a black, ovoid-shaped structure.
Now, the next video you're going to see illustrates another kind of call that they produce that's known as a "grunt." You'll see the names that these sounds have been given, which were done years ago by other naturalists other than myself. The names kind of match the sound sometimes. So that sort of sounded like a growl. Sort of if your stomach is grumbling, it has a similar sound.
What you're going to hear now is a series of grunts that they also produce when fending off other males that are trying to get into their nest. So in this case, there's actually going to be a male inside the nest, and he chases him out. And after he chases him out, he gives them a bunch of these calls to basically tell him, get out of here. Stay away. So watch. He's going to chase this male out. Boom, he leaves.
[FISH GRUNTING]
And those are a series of calls known as "grunts." Now, here, you see it again.
[FISH GRUNTING]
So he take-- and now you see there's actually another fish in the back of that nest there. That's actually a female that's in his nest. And at that time, she's actually depositing eggs in the roof of this nest one at a time. And that male will fertilize each egg.
But at the same time he's fertilizing the eggs, he's trying to keep other males out of his nest who maybe try to fertilize those eggs as well. So there's a lot of competition that goes on among these animals. But the use of sound is really important in communicating context and social meaning.
Now, this last video you're going to see is an illustration of the mate call that this animal produces. It's known as a "hum" for very good reason. You'll hear it. It's a rather remarkable animal sound.
Males of the species might make this sound continuously for an hour nonstop. And then they may pause, and they'll produce it again. And their goal is to attract a female to their nest. So now you're going to hear-- this is a male which has set up residency in this nest. This is his. This is the territory he owns. And he's generating this call hoping to attract a female.
[FISH HUMMING]
So that's that background noise. That's the mate call of this animal. And you can see why it's called a "hum." Sometimes people think of it as a foghorn or an outboard motor. And so I think, at this point, if anybody has any questions about the videos or anything about the work we've done, I think we could do that now.
AUDIENCE: What was the name of that fish? Or was it all the same fish?
ANDREW BASS: They were all the same fish. They're known as a "midshipman fish." And the reason they're called "midshipman fish" is they have bioluminescent organs all along their body as well that look like little pearls. And they reminded early naturalists on the-- of the buttons on a midshipman's uniform at the Naval Academy. So they called them "midshipman fish." That's how a lot of names of fish come about, like the other fish are called "toad fish" because their faces look like toads. Yes.
AUDIENCE: When did natualists first record fish making noise?
ANDREW BASS: Oh, there's a very long history to that. These animals' recordings date back to the turn of the last century. And so these recordings of these fish are also known as the "California singing fish" and the "canary bird fish." They're well-known in the popular lore of Northern California and have been written about and discussed in short stories that you'll see in local magazines and newspapers.
And so we're talking it's over 100 years that these fish in particular where their sounds have been known about. But we're talking almost over 100 years that fish have been known to make sounds, and it's well-known to fishermen. You talk to fishermen these days, anyone who's an avid fisherman, they've probably caught fish and found them making sounds when they're catching them. OK.
AUDIENCE: So are these amplified when you are showing them to us? Or how loud are they?
ANDREW BASS: They're loud enough if you have some of these fish in an aquarium, they're loud enough you can hear them in the aquarium, even fish this big. So--
AUDIENCE: [INAUDIBLE].
ANDREW BASS: Oh, yeah, you can be standing right next to it. I had the experience early on when I was studying these fish, I was standing on shore at night, and it was a quiet evening. You could hear the-- those humming sounds standing on shore. I mean, it's a remarkable experience to hear it. The sounds are that loud that they break the air-water interface. So this is a major form of communication for these animals, yeah.
AUDIENCE: And so fish today, [? are they ?] talk too?
ANDREW BASS: Yes, they do. There are fish all over the world that are talking. And the East Coast version of these fish are known as "toad fishes." And they are abundant along the East Coast and the Gulf Coast as well. They do similar kinds of things.
And the point is, so again, these fishes, they're really just the tip of the iceberg, what we're talking about here. There are so many fishes out there that we don't even know yet that they're making sounds. And there's so much yet to do. And I think that increases our appreciation not only for this group of animals but also for water environments.
And these animals are not only found in oceans, but talking fish, so to speak, are found in rivers, and streams, and lakes. They're abundant in all aquatic environments. We just don't know much about them because we don't see them typically doing it.
You see birds. You see frogs. You see other mammals. You know about whales and dolphins in the oceans making sound. They're well-known. But what we don't realize is how many fish are out there that are also making sounds that have a meaningful context and then to appreciate that they're using similar parts of their nervous system to do that, to make that behavior.
AUDIENCE: All right, now I have to ask a dumb question, but--
ANDREW BASS: No dumb-- there are no dumb questions.
AUDIENCE: What is the new part? And you knew the fish could communicate--
ANDREW BASS: Yeah.
AUDIENCE: --before. What is this-- why is there a [INAUDIBLE].
ANDREW BASS: Why is it new? It's the demonstration that, in fact, it's a similar part of the nervous system that these fishes are using as other animals use, including ourselves, that's essential to making sounds, and that would include human speech. And here, we have the simplest example of that collection of neurons in the nervous system that are used to perform that behavior, and that's new.
AUDIENCE: And why is that important?
ANDREW BASS: That's important because, clearly, to better understand how we make sound and how other animals make sounds, what neuroscientists want to do is we want to understand the earliest events in development that shape what those-- how those neurons are going to communicate with each other. If you better understand how they develop, you'll be better prepared to find solutions to when they don't work properly anymore. And so developmental neurobiology is one of the largest fields of the growing field of neuroscience. And now we've put-- these fish are front and center in trying to understand, in fact, how the circuitry in your brain develops that you use to vocalize.
AUDIENCE: Why did you pick this species of fish? Was it a simpler species to analyze?
ANDREW BASS: The reason I chose them was, in fact, my reading of the literature that was already out there. So I started doing this as a graduate student. I was a graduate student in studying the neurobiology of fishes, brain organization of fishes, and evolutionary biology of fishes. And I've just-- there was a lot of interesting things going on at the time, actually, when people were first learning about songbirds and how birds make sounds.
And I just started thinking, wow, wouldn't it be great to understand how fish make sounds as well using their nervous system? And it was really just from reading this literature that was already out there. I mean, again, within a small group of scientists among fish biologists, it's been known for decades that fish are making sounds. And the more I read about them, I learned, well, these fish are the ones that we might consider the champions of sound production in the ocean.
They are nocturnally active. They're breeding at night. And so their entire social behavior revolves around making sound and hearing sound. And so I figured, OK, those are going to be the best animals to study because that's where we can have the best chance of understanding how they're using their nervous system to vocalize. It's a major part of their lives.
It's just like you go out at night, and you hear frogs calling. Frogs depend on calling to reproduce. Well, these fish are equivalent to those frogs in the ocean. Without producing sound, they're not going to reproduce. It's essential to their social behavior, and that's why I chose them.
AUDIENCE: You said earlier that if in people the compartment was damaged, they would-- you would not be able to speak again. Are you familiar with instances where that has happened with people for some reason, a development or injury that's [INAUDIBLE].
ANDREW BASS: Well, you could have a stroke patient could have damage to that part of their brain. That could be damaged. Or in any other motor diseases, in a variety of motor diseases where individuals begin to lose the ability to speak, part of the reason for that is those regions of the brain are being damaged. So it's-- yeah, it's very pertinent to our own health and welfare.
AUDIENCE: Any other types of sounds that you've discovered besides those three?
ANDREW BASS: Those are the three major classes of sounds. Now, what's important to appreciate here as well though is that each species-- so here you've got like [? 25 ?] to 40,000 species. Each one of them may have a distinct vocal repertoire just as, you know, you hear different birds singing, and they all each have-- each species has its own kind of song.
Well, each of these group of fish probably have their own kind of song as well. Not only do the fish recognize the differences themselves, but you can easily pick up on the difference. I mean, you could hear the differences between those grunts, and growls, and hums. Well, there, we could play you the sounds of other fish which will be equally distinct to you.
And we've done many other studies with these animals over the years where we can demonstrate by playing back sounds to them that they will re-- they recognize the differences between those sounds. They know they mean different things in different social contexts. So again, the Laboratory of Ornithology, the Macaulay Library out there has a large collection of fish sounds already. And we actually-- we're working with them now to hopefully expand their library of fish sounds.
Because it's really-- this whole area of study really is very much a frontier. Again, there's a small group of biologists that have known about this for decades. But I think part of the importance of this paper is that it makes the public at large, and other scientists, and the community of neuroscience even aware of how these animals are using this method of social communication.
AUDIENCE: This might be a silly question.
ANDREW BASS: There-- as we always tell people in class whenever they ask ques-- there are no silly questions. There are no dumb questions. So--
AUDIENCE: So do any fish ever laugh?
ANDREW BASS: Do they ever laugh? No. There's no evidence to indicate that that would be happening. So that's a very human trait. And I by no means am saying that these fish have similar cognitive abilities as we have. This is really a very simple form of vocal communication.
But myself, no, I don't believe that they're doing anything like that. This is really the simplest sort of thing. I'm a male in this nest. I want to attract a female to the nest to reproduce or chasing another male away. It's that simple, I would say.
AUDIENCE: Can the females make [INAUDIBLE]?
ANDREW BASS: Yeah, great question. Thank you. Females also make sounds. They typically don't make sounds in this kind of a context in this group of fishes. But they make sounds in other contexts in a more of a territorial, aggressive context.
And they mainly make just that grunt type of sound. They do not make that advertisement call. They're not able to do it. They don't have the machinery to do it in terms of the musculature or the neural machinery to actually produce that mate call. So it's only males that are doing that sound.
AUDIENCE: [INAUDIBLE]?
ANDREW BASS: Yes, and there's a lot of other work that we do in my laboratory. In fact, we're interested in how hormones [? shaped ?] the development of the nervous system in males and females that leads to these kinds of differences that you're alluding to with your question. So it's a really good question.
Now, there are other species of fish though where females and males are both making-- robustly making sounds. But in this particular situation, it's mainly the males have the most dynamic repertoire. And you'll find that in many other animal groups as well.
SPEAKER 2: I don't want to cut this off, but if you guys have any other questions, feel free to ask them. Dr. Bass is going to show us-- we're going to go in a couple of cameras at a time because it's a small stage. So he's got a fish laboratory with-- I would say it's just pretty much a room full of aquariums that we can show you.
That would give you some B-roll, and you can ask other questions there as well. And radio folks are welcome to go in as well. So are there any other questions? So I guess we'll [INAUDIBLE].
ANDREW BASS: OK, we can go in there. Thanks for your time.
SPEAKER 2: Thank you.
ANDREW BASS: And, Aaron, thanks for showing the videos.
It's a long way from the dull hums of the amorous midshipman fish to the strains of a Puccini aria -- or, alas, even to the simplest Celine Dion melody. But the neural circuitry that led to the human love song -- not to mention birdsongs, frog thrums and mating calls of all manner of vertebrates -- was likely laid down hundreds of millions of years ago with the hums and grunts of the homely piscine.
By mapping the developing brain cells in newly hatched midshipman fish larvae and comparing them to other species, Andrew H. Bass, Cornell professor of neurobiology and behavior, with colleagues Edwin Gilland of Howard University and Robert Baker of New York University, found that the neural network behind sound production in vertebrates can be traced back through evolutionary time to an era long before the first animals ventured onto dry land.
Bass spoke to the media at a press conference, July 17. The research is published in the July 18 issue of the journal Science.
