They're swarming!
Learn about Swarm Intelligence from Simon Garnier, a scientist studying the behavior of insects in colonies. These amazing creatures organize and coordinate among thousands of members seemingly without effort. By studying the organizational patterns of these swarms, we can learn how to better organize things in the human realm.
Learn more about what Simon and his team are doing at The Swarm Lab. Music by Mathew Halpern. Thanks to Jennifer Palmer for her contribution to the editing.
Episode transcript
Parmvir: Alright, folks. Welcome back to our podcast. We hope you've been following our news via our social media sites. So Twitter, G plus and Facebook.
Our guest this evening is a chap called Simon Garnier, who has come all the way from New Jersey just to speak to little old us. Hello, Simon.
Simon: Hey hi. How are you?
Parmvir: Very well, thank you. We're glad to have spared you a little bit of the cold from the Northeast with this weird kind of cycling weather you've been having recently.
Simon: Yeah, I think it's probably the first time I see the sun in the last three months. So.
Parmvir: Can you please start by telling us a little bit about your background where you studied and how you ended up studying what you do?
Simon: Well, I guess I'm going to start with college because you don't care about where I went to high school,
Parmvir: Probably not.
Simon: So I started by doing a bachelor's in molecular and cell biology at the University of Bordeaux, that's in France, as you can hear from my lovely accent. I got a little bit bored looking at cells, growing in a Petri dish. So I switched to animal behaviors and neuroscience did a master at the University of Toulouse also in France. And continued to earn a PhD at the same place in Toulouse and credited with a PhD in 2008 The PhD was mostly about what I do now. That is about how large populations of animals or objects can organize themselves.
And, you know, do things together. And then after finishing my PhD, I moved to the US got a fellowship to go work at Princeton university. And about a year and a half ago, I finally got a position at the New Jersey Institute of technology in Newark, New Jersey, if it's Oh, and why I studied what I studied by accident.
I studied what I studied by accident. I originally wanted to be a journalist. And when I applied for journalism school, they told me it would be better if I had a master in something, because I will get, a job more easily. If I was a specialist of something, instead of just writing which dogs and cats were dead this week, that's how exactly you, how the journalists that I met during the interview told, spoke to me, so not making up this. And so I started science and loved it, completely hooked up on biology. And as I say, I got bored with cells because you could not see them move. So went to animal behavior, because you could see that move and was lucky enough to join the laboratory of Guy Theraulaz in Toulouse, who introduced me to all this fascinating world of how insects and human beings and fish and birds and all these social animals coordinate all their behaviors to do things together, basically. And since then I got the, you know, caught the virus of trying to understand how a world like us that's made of so many different parts is actually holding up together and how we ended up today [for this podcast] with maybe 12 different people, who just converged in this place. How did we manage to coordinate all this activity without too many problems?
Parmvir: Very cool. And I think your, your model of choice, is ants specifically, is there a reason you opted for working on those
Simon: It's cheap?
Parmvir: It's cheap.
[Parmvir laughs]
Simon: I don't work only with ants.
I work with everything that forms groups. So I did work with cockroaches and ants and robots and human beings and fish. And all sorts of things, but the reason why ants is so such a fascinating system is they are the only eusocial animals. So I don't know if you know what the eusocial animal is.
Parmvir: Please explain.
Simon: It's basically a pinnacle of social evolution if you want. So it's a, a society where even every, the task has divided between the different individuals working in the society, but even reproduction is divided. Only certain individuals in the, in the colony, in the, in the society are going to be in charge of the reproduction.
So really, really a division of labor is done at every level, including reproduction. So that's what we call it. eusocial animal. "Eu" meaning, I think, meaning true or real in Greek. So this is a really social animal because they even share tasks in terms of who can reproduce and who cannot in the colony.
So it's a, it's probably, you will find, I mean, there's like something that's 14,000 different species of ants actually that we know of probably double that. That we don't know of and, and all this all these species live in all these ants live in groups, all these species live in groups, but they have like very different way of organizing themselves.
And we can find colonies of ants, maybe 10, 20 individuals that can live in an econ and colonies of one since the leaf cutter ants that you find in central America. Can live in colonies of up to 20 millions individuals with a queen that can live 20 to 30 years producing. I think the numbers is that something like 500 millions individuals in our lifetime.
So it's, it's, you're talking huge numbers and you're talking about ants and so individuals who have a tiny, tiny, tiny brain. I mean, it's maybe 250,000 neurons
Parmvir: Compared to a human brain.
Simon: Yeah. It's like 19 billions in humans. Yeah. Ends up very tiny brain. They have these huge colonies and huge societies, and it's just fascinating to try to figure out how these tiny brains can manage to. You know, works together into something that actually functions properly. Just imagine how it can be hard for us to sometimes just organize a meeting or get people to agree on something. And there's only five people in the room and the 20 millions, and they need to work together toward the same goal, which is helping the queen produce as much as possible and creating new queens that will then colonize different other places in in where they live.
Parmvir: So that would explain why the infestation in my office is just, never ending.
Simon: Yeah. They're better than us they're, they're. They're just better. They're just better organizing than us. So, yeah. I'm sorry about your office.
Parmvir: So can you explain why you often see ants just going along in a little trail? What is it that determines their behavior in that sense?
Simon: What you see there is probably an ant, a scout ant. You know, went out or a bunch of them went out of the colony in the morning. They looking for foods and once they find food, they come back toward the nest and they leave behind them a film on trail.
So it's a, it's a chemical substance that they lay on the ground. And this chemical substance uh, has, has two actions. One is to recruit ants inside the nest. So the ants, when the ants go back to the nest they, one sort of excites the other ants. And they want to go out to forage because they've been informed there's food out there.
And then also guide the ants to other food source. So they will use antennae and tap the antennae on the ground to smell. The antennae are basically their nose. And so they smell, the, the ground and find a trail and follow these trails to the food source and then take a bit of food and then follow back. I mean, the trail back to the nest and also reinforce this trait as they walked back to the nest, but more pheromones, which recruit more guys.
And so. What you can get is huge number of ants on these trails. I mean, you talk about traffic that can reach in some species, maybe, you know, 60 hands per second traffic really, really, really massive, huge in some species. So it's, yeah, once again, compare these two. I don't know how is the traffic here in Tampa, but traffic in New Jersey, as soon as you have more than five cars on the road, there's an accident. And then there's a traffic jam. Ants, ants don't have this type of problem. They can organize gigantic traffic on the trails using this pheromone to attract more and more guys. And then that's how they find your sugar and then attract all the colony there. And that's how your office gets invaded.
Parmvir: So given that they, they tend to behave, they behave as a group, what is it about the species that leads them to behave as a group? I mean, I guess humans do it to an extent, but they're not as organized. So these guys, like when they, as I understand it when they're in these little trails, they will walk at kind of the same speeds and make sure they don't bump into each other.
Simon: No, they bump into each other a lot. Oh yeah, it's, it's a huge mess there. But the difference with us in our cars is they can bump into each other and there is no damage. They can walk on top of each other. They can, they're very resistant animals. I mean, they're, they have an external skeletons, you know, most sensitive, all insects have this and you can drop an ant from a building and it will be fine.
And so they can. They can actually bump into each other very frequently. So some, it depends on the species, some species like army ants, for instance, that you find in you know, Costa Rica or every part of central or South America. These guys there, what they want is to optimize the maximum the traffic because they they need to bring the maximum of food back to their temporary nest to feed the larvae, et cetera. And so they will organize the traffic into lanes, so that will keep the central lane sort of open for the ants that are carrying items of food. And while the ants that are going toward the battlefront, to where the food source is, are going to occupy the side of the road. But all the ants, like the leafcutter ants, they're not trying to necessarily maximize the amount of leaves they bring back to the nest, but they try to maximize the quality of it.
So they actually sort of like to bump into each other because each time, they bump into each other, they can taste the quality of the leaves that someone else is bringing back. So it's also a way of transferring information. So depending on what is your interest, what are you trying to optimize? The total amount of food you're bringing back to the nest or on the contrary to optimize the quality, you will either organize the traffic very very, very strongly or in the contrary, you will make sure that traffic is a huge mess. So your information can spread fast along the trail.
Parmvir: So is there a specific aspect of this behavior that you're researching now?
Simon: So I currently have a graduate student who just started working on, on. I would say the supply chains of the leaf cutter ants. So in particular so the leafcutter ants are a very particular species, probably the most fascinating insect for me, at least one of the most fascinating one.
What they do is they go outside, they find particular trees or grass that they like, and they cut pieces of it and bring it back to the nest. And in the nest, they give these two smaller ants that cut in smaller pieces and then use it to grow a fungus into their special chambers that they have inside the nest. So they basically invented agriculture if you want a million years before us. So what we interested in, what my student's trying to understand better is is this all supply chains from like cutting the leaves, transporting the leaves back to the nest and sometimes back to intermediate caches that they leave along the trail.
So we have sort of like warehouses along the trail, where they drop some of the leaves and they are going to be picked up by other, other ants later. And then once it's inside the nest, there's also warehouses inside the nest to keep leaves for sometime until they can be processed and then fed to the fungus.
So you have a whole supply chain and then the fungus is used to feed the larvaes inside the colony. So you have a whole supply chain here, and we're trying to figure out how they sort of optimize or how they, they, they make sure that all the different parts of the supply chain work together. So you don't have, two big supplies of leaves, at one point when the nest cannot process all these leaves on the contrary, you have enough leaves, always coming to the nest to avoid that the workers inside the nest have nothing to do with the production of the fungus stops. So it's a starting project so I can't really tell you much about it right now, but it's the whole idea is really to study these whole supply chains and we're working with people doing operation research. So I don't know if you know operation research, basically all the people trying to optimize everything in our lives. Optimize how trucks and a warehouse have enough to go to this and that supermarket you know, when do they have to leave? What route would they have to use, et cetera. So people trying to optimize all these aspects of I don't know. I don't want to say. It's not processed. There's a word for that. Which I forgot excuse my French.
Anyway. Yeah you understand what these people are doing. So we're working with these people to try to use their tools, to analyze the supply chains, figure out where the ants are good at optimizing part of the supply chain, making sure the supply chain works and hopefully in two or three years and when the project is completed, we might be able to use what, what we have learned from the ants to design new algorithms and new ways of optimizing supply chains in human societies. I mean, it's a long-term project. We might never reach this point, but you know how science works [laughs] and you can get this out of the podcast.
Parmvir: So you guys do a lot of field work. Does that mean you get to travel around a lot?
Simon: My sort of like research philosophy is to try to integrate as much as possible. Field work laboratory experiments and, and theoretical or modeling work. So I don't get to travel a lot, but my students and my postdoc , my postdoc just came back from Panama a week ago, um working on a completely different project. My student is probably going to go there either this summer or next winter.
So yeah, there's a lot of traveling involved in, in our work, especially when we, we go into the field to study these particular systems. But as much as we can, as much as possible we try to study the system in the lab, which is not always possible with some species, the army ants, I was telling you about earlier they are nomadic ants, so keeping them in the lab is, will be a huge nightmare. They need, they need a lot of space. So it's not possible to keep them. So we have to bring the lab to the field and build, like particular setups to be able to record what we want there. And then as I said, we try to do as much as possible experiments in the lab.
Most of the experiments we do are behavior experiments. So we try to observe the behavior of the animals and in particular, how they move in the environment it's a function of what's around there, you know, the distribution of food sources or where the nest is located, et cetera. And and then as much as possible, so we drive mathematical or computer models from these, to try to explore a little bit further properties of the rules that the ants are using to organize their colonies and see why why they've basically chosen this or why evolution chose this world for them. Figure out if they optimize some sort of output for the colonies, like the amount of food, they bring back, or the amount of information they exchange for instance. And , and it's also trying to find in which condition these rules might fail. So basically why evolution has pushed the system in this direction and not in another direction.
Parmvir: Very nice.
So I think we're going to move on some questions that we have from people. I was speaking to my friend, Kathy, very recently. And she was telling me a story about how she was hiking in the mountains in China, I believe. And she said a group of her and her friends were just up there. And all of a sudden her friends said duck because there was this massive swarm of bees coming towards them.
So I guess the question is what is the trigger for that kind of swarm behavior?
Simon: Well I'm not a huge specialist of honeybees, but I will, I will first guess they're honey bees and not, other type of bees cause there's a lot of species of bees. Yeah. But usually the swarms, honeybee swarms that you see in the US or in Europe or wherever they, they keep honeybees, when the colony has reached a certain size, during the summer , the colony will produce a new queen and the old queen usually abandon the nest and leave with a part of the colony. Maybe 10,000 ants..bees sorry, are going to follow the queen, the old queen. And they're going to try to look for a new place to nest basically. So the old queen is abandoning the old nest to the new queen and then go found another colony somewhere else. And that's how, that's how basically ant, bee colonies, sorry, reproduce. And it's similarly some ant colonies are produced the same way.
Parmvir: This one is from Arturo. So do you ever find rogue aunts? Do they ever break from the crowd?
Simon: Yeah. So that's a big it's not, it's actually a very, a very big question right now. So there's 14,000 species of ants and they have very different types of organization , social organization. Some of them like the army ants or the leafcutter ants that we talked about already are very. cooperative. So they they try to, well, they work for the good of the colony somehow and some of the species it's a less clear in particular in more I would say less evolved by evolve, like they're not more stupid, but they just, they just have evolved earlier than other ant species. You you'd have conflict between the the workers because in these colonies, the, some of the workers can actually reproduce. So you will see a dominant hierarchy appearing, so fights between the ants to decide what's going to be the next ants that will be allowed to reproduce And, and in this species you're yeah, you have a lot of conflict.
And so you can have like rogue ants, if you want trying to trying to cheat the system by reproducing while it wasn't allowed to reproduce by the other queen. So you have then, so then you have a policing appearing. And so other ants are going to try to basically beat the crap out of this poor guy who tried to cheat the system and and prevent, or even kill these ants to avoid that it reproduces when it's not allowed to.
Parmvir: So that's very interesting. So this leads onto another question we have. So the ants that are not part of these reproductive, [reproduc]tion tasks, sorry, those presumably do not easily pass on their genetic information. How did that evolve?
Simon: So, the genetic organization of the colony, if you want is in a typical colony you have one queen you have to know that the males are homozygotes, so they only have one copy of all the genes. It's not, it's not like reproduction in mammals, for instance, where you get half of your genes from your mom and half of your genes from your dad. Here, you're going to have the same copy as what your dad had before. And then you share only half of the rest from your mom. So the idea is, is a, if you look at the numbers you would share with your sisters. Cause only, only the females have two copies of the genes, you share with your sisters 75% of your genes because 50% of them come from the same male and the other 25% that you share, one, either one copy or the other copy of the gene of your mom. So in average, in these colonies where you have only one queen and the queen mates, with only one male, you share up to 75% of your gene with your sisters. So cooperating with them, actually you get a better fitness in general, by letting only one queen or set of queens to reproduce, then you will get by your policing yourself because you would share only 50% of your genes with your descendants.
That being said, it's a little bit more complex than that. So I don't know how much in the details you want to go, but if you look at modern ants, like ants today, you will find that in many colonies you have more than one queen, you have multiple queens that mates with multiple males. So the actual relatedness between the sisters and between the queen and daughters actually can be less lower than the 75% or even less lower than the 50%.
And that's a big question if you want , for people studying these systems, because it seems to suggest that back in the days when sociality evolved in ants, it evolved because of this link of like this, this hierarchies, in these colonies with only one queen. But once the surety was established, this relatedness was not necessary anymore to keep the surety working because the advantage of being in groups are so huge.
I mean, you get access to food more often, even if you share only a little portion of your genes through the queen, because you have a low level of relatedness with the queen, always the sisters you get you get so much, so many benefits in being in such large colonies in terms of food and potentiality, of spreading new offspring, that share even a tiny percent of your genomes, that the system stays stable after that.
I don't know if it's very clear, but the idea of once again, if we go back to this leaf cutter ants, the queen produce five alpha billion individuals in his lifetime. He may be a hundred millions of them are going to be new queens, potential new founders. So imagine the potential of collaborating with this type of power. Cause it's really a massive, massive amount of power you have to produce new potential colonies that that's even if you don't, you have lost this relatedness level with your sisters. You're still gaining a lot of advantage in incorporating this system. So let's say the a, that the five second explanation is in typical end colonies you have a higher level of relatedness with your sisters. So you collaborate, we incorporate the more complex picture is yes, but once you've created these gigantic colonies, when you've reached the states of evolution, you don't need it anymore. And the simple weight, if you want of the sociality is going to maintain the social system stable.
Parmvir: Okay. I guess Kim's been looking up your website because she wants to know what is slime mold?
It's my new favorite organism . Sorry ants.
That's not true. I love ants almost as much as slime mold.
So slime mold isSimon: , first of all, it's a word that that's not very good word because it's sort of encompassed a lot of different organisms that are not even related with each other.
So the slime mold we work with in the lab is called Physarum polycephalum, sort of like yellow goo. It's not very sexy and not very appealing, but it's a, it's an organism that's actually a unicellular organism that can be as big as the table we are sitting on, or at here today and it's just one gigantic cells, composed of billions and billions of nuclei.
So yeah, so this slime mold is something you can find in, in the one we use, this can be found in, temperate forests. You can find easily in the US or everywhere you have temperate forests. If you, if you walk in the forest and you find a sort of like yellow, very bright yellow, sort of moth on the side of a tree that's polycephalum , Physarum polycephalum.
So I think that's the best answer I can give you about what slime mold is, because it really encompasses different organisms. They are another type of slime mold that is very well studied called Dictyostelium , which is very fascinating too. So in this case, it's, it's a bunch of unicellular organism with only one new nucleus.
But they have this property, when the environment gets a bit harsh, the food gets less important. They start releasing cyclic AMP in the environment and they use these to signal the other cells around. "It's time to regroup guys and to form spores together". And so they're all these cells that are not necessarily related to each other, are going to come together attracted by this chemical signal and form these sort of structures that on top of it has a spore. So the spore is basically dried pieces of the slime, all of these dried cells and the spore is going to then release these cells in the environment. And hopefully they, one of them are going to end up into a better place where you can start growing again. So it's a, it's a unicellular organism that leave most of its life by itself. When the conditions are harsh comes together and creates a structure that helps, some of them, not all of them and helps some of them just tread further and find a better place to live.
Parmvir: Interesting. David always likes to throw in these vaguely controversial questions. What's the bigger question you're trying to find an answer to. And why do you think it's important?
Simon: As I said at the beginning, the thing that I'm really interested in is trying to figure out how these very complex systems, composed of millions and millions of things working together. And so human beings or whatever you can imagine, your cells, the cells that form your body and your neurons in your brain. How do they actually synchronize the activities to actually produce something that's meaningful? That solve a problem for this particular group of organisms. And a big question here is how do we make sure that all these different parts, different objects follow the right sets of rules to reach the right behavior that you want to achieve. And in which condition, these systems are going to fail and how reliable is the system to get out of this failures?
If you, if you look at traffic jam it's it's, what's interesting is as traffic jams could be completely or mostly avoided if we could find a way to have everybody maintain their speed on the, on the road. So if everybody was doing exactly at the same speed, and if there was no places on the road where people were forced to slow down even a little bit you will not get traffic jam or very, very, very rarely. So the reason is, doesn't happen at low density obviously, but when you're interested in the density of cars on the road is someone slows down, just one car slows down for whatever reason, the car behind is going to have to usually slow down to avoid collisions.
And you're going to be, it's going to slow down slightly more than the car in front of it because you know, you want to keep your safety barrier, safety net. And then the car behind this car is going to slow down also to avoid collision with the car in front, and then the car behind is going to slow down, slow and so on. And so if you have this sort of cascading behavior of people slowing down that propagates backward from the original car slowing down. And if you push this far enough the car, after a certain time are completely stopped and it's just happened because one car slowed down to avoid, I don't know, a cat crossing the road, or just whatever reason, because this person decided to drive more slowly this day.
And we reached this particular density, and the traffic it's not that high, actually, this car slows down, this cascading behaviors and, and a mile behind everybody stopped. So another question is we have a system here, which obviously a complex system with different entities, your human beings in their cars interacting with each other, and the system fails dramatically because of these cascading behaviors. Can we, can we imagine a system or can we imagine ways to avoid or to limit these type of failures into human systems, for instance? So I'm not sure it's a big. question in the sense of the scientific lab. It's not relativity or, or, or evolution kind of question, but it's it's how can we learn from nature, from how ants functions generate that traffic, or how fish coordinates their movements together, et cetera, and apply these to some of human problems that we have that are caused by our inability to coordinate our behaviors on very large scales without having a central necessarily central control of this.
So we're very good in human beings that controlling things with heirarchical society. So we have a person or some people making decisions for everybody else, and then everyone sort of tries to follow the rules. That's why, you know, people make rules for how we drive on the, on the road. We didn't make these rules someone, made them for us hopefully for good reasons.
But as soon as you put a bunch of people on this road there, problems are gonna happen. As soon as you put a bunch of people that don't follow the rules exactly, that go a little bit too fast or a bit too slow , and you reach these sort of critical densities of people on the road, or even you can see of crowds of pedestrians going into stadiums or whatever, we're very bad at self-organizing and we fail and we get these, these massive traffic jams or in worst cases, in case of pedestrian crowds, we get people trampled in, you know, in and out of stadiums or going to gigantic parties or whatever. It's about two, three years ago now the, the gay pride, I think it was in Bremen I believe, I don't remember which city in Germany, but it was exactly what happened. They, they forced a huge crowd of people to go under under, I think it was a bridge and the crowd reached these levels where there were so many people at the same place that as soon as someone started panicking, because you know, you're stuck there you can't move you're so pressed by the crowd around you and you have, you're not strong enough to repel the people around you. So you start suffocating. People panic. Panic spreads in the crowd and then you have, 23 people died or something like this. Maybe more than that. So how do we manage to learn from nature and some example in nature that solves these type of problems, can we, can we learn something there to help us design better this type of events? So these type of situations and try fully to avoid these kind of problems.
Parmvir: I think that was a great answer to the question. Yeah,
Simon: Well it's not a big question, in a sense, we're not solving big problems, existentialist problems of, you know, where do we come from and where are we going? But it's like, what do we do now with what we have? And with own capability of organizing self-organizing large crowds.
Parmvir: A question from Adam. And this is whether eusocial animals have language.
Simon: Whether they have language?
Parmvir: Whether there's any sort of language other than the chemical communication that they use.
Simon: Well, I don't think language and eusociality are tied. I mean, human beings, we're not considered eusocial animals.
The reason is we, we, we don't have a cast of individuals that are the only one allowed to reproduce. Everybody potentially can reproduce in human society. And we have probably the most evolved language. So now, if you, if you think about language, I guess what the question refers to is probably the language of the bees, honeybees of this particular, the talk by dancing, if you want.
When they find, when a scout finds a new food source, the scouts come back to the nest and then execute this particular dance. And that's how they recruit. They inform other ants that, of of the presence of food there, and then the lengths of their dance. How many times. They do the executive, this dance, the more the dance, the more they recruit bees to all this food source, the better the food source, the more likely they're going to dance for a long time in rock and roll of bees.
And then these bees go to the food source, taste, the food source, bring some, and then dance in turn. And then the information is spread across the colony. And soon a large portion of the colony is going to be dedicated to exploiting this food source. So that's a form of language because it's transferring information directly and it's not based on chemicals in this case.
Parmvir: Well, thank you very much. So the usual crowd, so my self Parmvir Bahia, Arturo Araujo, David Basanta, unfortunately, Angela's not with us tonight, but we do have our regular sound engineer in the form of Raphael in the corner. Yay, Rafael. And thank you very much Simon. It's been a very interesting evening. Thank you.
Thank you very much.
[Musical outro]
Simon: EO Wilson is probably the most famous or one of the most famous biologists alive today. He's a professor at Harvard and is extremely famous for having, I mean, he's written Pulitzer winning books on ants. "The ants" it's called is very famous also far having driven the whole sociobiology revolution. So, I mean, he's a big guy he's like a big shot. And I had the chance to visit Harvad a few months ago. And I was really excited. I was invited by people at the math department that I was really excited because I, I wanted to go and knock on this door and go say hi to him. And unfortunately he got sick that day and he wasn't in the lab.
So I ended up in front of his door and I was very sad. And for about 10 minutes, I just took picture of his door. So I have a perfect picture of, of, you know, saying I was there. I went that close to God. But God wasn't was, was sick that day.
[Audience laughing in the background]