Polyvox Podcast

Célia (Host): Hi and welcome. I’m Célia Lazzarotto, communication officer at the NCCR Evolving Language, and today, I’m welcoming Théophane Piette, researcher at the NCCR Evolving Language, in the lab of Didier Grandjean at the University of Geneva. His speciality is neuroethology. 

Théophane (Interviewee) : Hi ! 

Célia: So, Théophane, what is neuroethology ? 

Théophane : Neuroethology, in simpler terms is the neuroscience of animal behaviour. So, we’re trying to explain the behaviour of animals by looking at their brain, trying to understand what their brain is telling us about their behaviour, and how much it influences their behaviours.  

Célia: You recently finished your PhD, where you studied animal communication. What’s the link exactly? What interests you in this topic ? 

Théophane: So, I got interested in the rhythm of vocalizations and “animal speech”. The idea was that actually this rythm is something very important in the human language. When we look at human brains, when someone is speaking to us, we see that the rhythm of certain brain waves aligns with the rhythm of parts of the speech, like syllables or phonemes. And we asked ourselves if there was such a great importance of rhythm in animals, and if we could link that to mechanisms in their brain.  

Célia: And did you start this by chance, what brought you into this field ? 

Théophane: Ah, it’s going to be a bit of a long story. I have originally a background in cellular and molecular neurosciences, so I studied the inner mechanisms of cells and neurons a lot. And I ended up in a masters of neurosciences and neurobiology in Grenoble. At the end of my first semester, I did an internship in immunofluorescence, on a project about Alzheimer’s disease. Basically for 3 months, I was locked in a dark room, during the spring and summer, not seeing the light of the sun to look at fluorescing cells, and 80% of the time, it didn’t work. So after 3 months, I told myself, “no I’m gonna become depressed”.  

So I took a year off, to figure out what else I wanted to do. I ended up doing a 6-month internship with the professor Adrien Meguerditchian in Marseille, about the development of the behaviour of baby baboons – so Anubis baboons, very small ones which were very cute – and at the same time he also had projects about lateralization of communication in baboons. Baboons have a type of gestual communication where they hit the ground, and he looked at if the baboons were doing it more with their right or left hand. He showed that actually, baboons use their right hand more often, which means the information comes from the left side of the brain. And this is super interesting, because in humans too, things that has to do with language are very centralized on the left. So there’s a sort of evolutionary continuity for this lateralization of communication.  

And I found this internship absolutely incredible and said to myself, “ok, I need to do this afterwards”. And I was lucky enough to meet Didier Grandjean, my professor today, who told me, “Come to Geneva, we’re doing great things”. So I came back to university, finished my second year of master’s in Geneva, and then I discovered that the NCCR Evolving Language was getting started. So I contacted a few professors, and that’s how I ended up doing my thesis with Professor Anne-Lise Giraux, who’s now in Paris, on the evolution of rhythm in animal communication.  

Célia: During your project, you worked with a lot of animal species I think. Did you study them in real life ? How did you study them ? 

Théophane: So yes, actually, the thesis a big project that will be divided into a few smaller projects. And together, they create a bigger project that makes sense. For me, in my thesis, the first project was to evaluate the evolution of rhythm in animal communication. And for this, I studied the vocalizations of around 100 species, from birds – from the small sparrows we have in cities, to ones that are not as well known like hoazins in South America – but also mammals like whales, dolphins, lynxes, deers… and some insects as well as a few fishes (I actually learned during my thesis that fishes can communicate with sounds!). So we studied the evolution of rhythm in all these species. This was our first topic. And afterwards, the second topic was to look at if, as we see in humans during language processing and production, we could see that the rhythm of brain oscillations of animals could match the rhythm of their vocalizations. So see if this mecanism is very huma and to the complex structure of language, or if it was much more common and rather linked to the analysis of sound in general, in the brains of animals. And this, we studied on 2 species, which were dogs and baboons. 

Célia: And what are the results of this ? Is there a meaning behind these oscillations ? 

Théophane: So, what we showed in our first study was that there was a sort of common rhythm in animal communication, that was conserved in all species, around 3 hertz, so 3 sounds per second. We really noticed that in the majority of species, from the whale to the cricket, and the sparrow, that communicate at this approximate rhythm. It is really conserved in the various species. So this was already incredible.  

Celia: And were there variations depending on the size of the animals, or depending on the species, for example, if mammals were closer together or not ? 

Théophane: So actually, this was a surprising result : we didn’t find anything that could influence the rhythm directly.What needs to be taken into consideration is that I’m not saying that the environment can’t have an impact on the specific rhythm of a species, or that within a family of species, the weight of an individual compared to another won’t influence its rhythm. What I am saying, is that at a much bigger scale, what we call macro-evolutionary scales, these factors don’t influence the rhythm. We have a conservation of this rhythm, no matter the size, the environment, the social complexity of the individual… All this is conserved in the evolution of the different species.  

Célia: Your second project with baboons and dogs, what was the finality of it ? 

Théophane: So, it’s still going on a bit. On dogs, it was a study that I joined, that was led by Dr. Eloïse Déaux, in Anne-Lise Giraud’s lab. The idea was to ask how dogs, that are used to being with humans – we know that they understand many words and things we tell them – how do they process language? So I said that the rhythm was important in the human language. Notably, we know that the rhythm of syllables comes in range of rhythm that we call theta range (4-8 syllables per second for most languages of the world). And we see that the cerebral oscillations that we call theta waves between 4-8 Hz, they come and match their rhythm to that of syllables when we listen to someone talk. And what Eloïse’s study on dogs showed, was that dogs will rather use slower waves, which we call delta waves. So this time, it corresponds to the common rhythm we found in animals. So they’re going to process language at this slower rhythm, and not with theta waves like humans do. 

Célia: And afterwards, we humans adapt to this rhythm. 

Théophane: That’s it ! And this is why when we talk to our dog, we go a bit gaga. We talk slower, with a high-pitched voice, like we do often with babies. It’s a parallel. Probably because we adapt to the rhythm that they use, more than the opposite. We adapt more to them than they adapt to us when we speak, though it’s already incredible that another species can understand words we say, we are adapting a bit to the constraints.  

Célia: Okay. And with baboons, have you tried to do the same thing, or did you have another approach?  

Théophane: So, with baboons, we asked a bit of a different question: we asked how they analyze their own vocalization. So rather than making them listen only to human speech, we also made them listen to baboon vocalizations, to see if there was a difference in the way their brain were analyzing human vocalizations vs language vs noise with a rhythm that resembled vocalizations. 

Célia: And then, what were the results of this ? 

Théophane: It’s still ongoing, so very preliminary. But what we seem to see is that contrary to dogs, which will analyse language and their own vocalizations probably in a slow rhythm, the baboon will be able to do both! The vocalizations of baboons are around 3 Hz, like other animals, and humans around 5 Hz. When they hear sounds from baboons, they will track these sounds with their delta cerebral zone (slow). And when they hear human speech, they’re rather going to track it with the theta cerebral waves (faster), just like a human listening to language. So, it’s a bit like there was an evolution, slowly, withing primates that developed a more rapid rhythm, that may have enabled the development of language, that allows to send more information per second than the other animals. But this is very preliminary, I’m not saying that it is the absolute truth.  

Célia: So, in its entirety, what do all these small studies assembled tell us, in the end ?  

Théophane: This is an interesting question because indeed, the goal of a theses is indeed to create a coherent story with all our small results. So, if we take our results, we have : 1) a conservation of animal communication at a certain rhythm, around 3 sounds per seconds, 2) and we have baboons, that can follow both slow sounds when it’s their own species, and rapid sounds, when it’s human’s, 3) and we can compare this to dogs, which seem to only follow slower sounds, and humans, that are more interested in rapid sounds. Let’s say it like that. 

And in fact, this allows us to develop a theory about the evolution of communication and the basis of its analysis by the brain; how closely these are probably linked to sound analysis in general. To understand this, we need to imagine a small animal arriving in the world, in its environment, and unable to hear any sound. And suddenly, it develops this ability, a kind of ear, something, and it can hear its surroundings. So now it faces two challenges. The first challenge is that he must be able to detect sounds as soon as they occur. Because if you detect a sound too late, let’s say it’s a predator approaching, chances are you’ll die a little too quickly. But you also have to be able to identify one sound from another. We are not supposed to react the same way to a river flowing beside us or a friend approaching us as we do to a predator approaching us. 

And so, what we think is that in order to do this, animals need to analyze sound at two different frequencies. And in fact, this is based on a physical phenomenon used in sound analysis called Fourier transform. But in fact, what this Fourier transform tells us is that if we use a long analysis window, i.e., at a slow rate, we will be able to differentiate between the different frequencies, but not really know when they occur. Conversely, if we use a fairly short window, i.e., a fast rate, we will be able to detect very well when the sound arrives, but we will not be able to detect what is inside it. So, in fact, we believe that animals need to analyze sound at two speeds, slow and fast, in order to do both. And in fact, we think that communication has adapted to this organization of sound analysis that already existed in the brains of animals, that it is not something that was created specifically for communication, but that it is something much older that comes from constraints that already existed in the basic analysis of sound. 

Célia: Super interesting, and all this research, that’s actually quite theoretical, how do you see it helping society, or bettering something for people in their daily lives? 

Théophane: So first we must separate the different studies, from the big global results of everything. If we take the study with dogs, there is a simple consequence : talk to your dog slowly if you want it to understand. And then from the results on animal vocalisations, well you can play a fun game that consists in listening to the animal species outside, and suddenly you’ll realize that all are in this common rhythm, quite slow. Personnaly, I can’t get over this information. Anytime I hear it, it’s terrible. Also, we see a lot of system that are developing typically on the automatic recognition of animal vocalizations, extracting the vocalizations of animals from the environment to be able to identify them, for example to count the animals, or detect the presence of certain species. We can imagine that this information could be used for example to better the detection of certain vocalizations. So it seems very theoretical like that, but actually there can be more direct implications.  

Célia: It’s also important to know how they work to be able to take care of them, i picture ? 

Théophane: It’s always important yes. The more we understand how animals function, the more we can take care of them. And when we go on the topic of evolution, of language and of brain waves in animals and humans, it’s way more theoretical. We are trying to understand how language could evolve to be such a complex communication system. And even if now I don’t see the implications, that doesn’t mean that there won’t be any in the future. For example in the field of auditory aid, for people. Understanding how the language was built and on which basis it functions, it allows us to understand how to give it back to people that don’t have it anymore, for example. 

Célia: You finished your PhD a few months ago, so what are you doing now that this big slice of your life is over? 

Théophane: It’s going to seem a bit depressive at first, but I promise it ends well. So, it’s a question we are asked very often “you just finished your thesis, what are you going to do now?”. The classic scenario would be to do post-doctoral contracts – for people that don’t know, it’s small research contracts, typically lasting 2-3 years, which we often go to another university to do, it’s often asked for. And then we can apply to become professor… So here is the academic path, the goal is to become a professor somewhere.  

On my part, I decided not to pursue this path, not because I don’t like research, I absolutely loved all I did, my PhD… Right now I still have a small research contracts with Didier Grandjean. So really, I love the concept of research, and I love trying to better understand animals, and how their brains work. But I’m facing a contradiction, which is, and that’s when it gets a bit depressive, we are aware of the problem that there is a decline in diversity, with global warming, human activities, and others… So we are losing a lot of species every year. So I came to the conclusion that I had a hard time being interested in understanding animals at the same time that their very existence is threatened. So I decided to focus my time and energy on protecting and defending biodiversity rather than understanding it. There’s no guarantee that one day things won’t get better, and I’ll say to myself, “Great, I can go back to understanding it.” But for now, I’ve decided to concentrate on protecting it. I hope it works. 

Célia: Yes, and outside this, you’ll still work a bit at the NCCR. 

Théophane: Indeed, I managed to get a part-time lecturer position at the University of Geneva to help master’s students write their theses on affective psychology. 

Célia: So, as a result, the auditors will soon find you again as a host for this podcast, in the next episodes. 

Théophane: Indeed, i’ll be on the other side of the mic ! 

Célia: So there you have it. Thank you, Théophane, for telling us about your research. We’ll see you soon for new episodes and to discover the research of other scientists and researchers from the NCCR Evolving Language. 

Théophane: Good bye and see you soon !