The French Book of the week is interested in a much more varied world than we think: that of ants. It is the result of years of study by two researchers around the world: a journey into what they call organized chaos. Explanations with one of the authors, Antoine Wystrach.
Antoine Wystrach, you are an ethologist, in other words a specialist in insect behavior, and you are co-signing with Audrey Dussutour The Odyssey of the Ants, published by Grasset. To be exact, it is the odyssey of a small part of the 13,000 species of ants.
Exactly. A subsample of the variety of the animal world has been given. Insects represent a large part of the animal world. Ants, in terms of biomass, there are a lot of them. Afterwards, we didn’t make 13,000 chapters corresponding to the 13,000 species. We talk about 70 species in the book. And within these 70 species, only some of the ants are presented.
We have chosen to talk about those that come out of the nest to look for food, because that is where they come face to face with the dangers of the outside world, and reveal all their cleverness and intelligence. There has been a lot of research on these ants. So it’s a very small percentage of the individuals in this colony. And for these individuals, we only speak of certain adventures. So we only have a very small sample of the richness of life.
For those that you call the “foragers”, going to look for food is a little like for others, ridding the anthill of poisons or toxic plants: it is a task that is entrusted to the ants older…
Generally, most species do this. It’s dangerous outside. Inside the nest, it’s not so dangerous. If you have invested to go from an egg to a larva to an adult individual, as much as it pays off this blow by working in the colony without risk. Once she’s older, that’s where she can risk her life. That’s what evolution chose for these insects. So it’s the old ones that we send to hell.
Why are you mainly interested in forage machines?
Ants are best known for their social organization in the nest. That’s often what comes up. But there is also the incredibly sophisticated side of an individual that we don’t often talk about. And when the foragers go out alone, or in the group, when we observe individual strategies; they express themselves fully outside the nest.
So these are stories that we are not used to hearing. And people are surprised to learn that an individual can memorize his environment, he analyzes, he has a brain… All of these are things that we don’t really know.
You describe a hunting scene: “mandibles spread apart, body flattened, antennae pointed…” How do you observe something so small?
The book is a tribute to all these naturalists who are disappearing. It’s a style of research that you don’t see too often anymore. For about 200 years, there have been people who have observed insects in detail (there are writings that have been found). Indeed, it is above all patience. At the time, it was also associated with drawing, sketches, postures, full of details. It’s incredible.
You talk about naturalists. We have the impression that you regret that there is no longer this taste for naturalistic research…
The fashion of research at the moment is very centered on technology, tools, the big data, things like that. There always has to be something from neuroscience and modeling. As a result, naturalist research is seen as old-fashioned, when in fact it is an absolutely monumental source of inspiration. It’s a shame that it’s gone.
We learn that when an ant dies, it is immediately put away from the others, that to move, they can create a suspension bridge or a fairly solid tunnel. What amazes you most about ants?
I think it’s the diversity that we observe from one species to another. Completely different worlds. Each individual creates a universe for themselves through their stories and it’s when we take the measure of this diversity that there is between our feet… So, it’s a mise en abyme.
There are some that are in a very visual world that move with furtive steps, little jumps, that look around for the slightest movement to hide behind a leaf while you have other species that are completely blind, very olfactory , to listen to their congeners to make these long chemical tracks. So imagine, it’s a completely different inner world. When you take the richness of all these micro-worlds, I think that’s ultimately what amazes me the most.
That’s what we said at the start. There are 13,000 species and depending on the species, we can have completely different types of organization.
Completely. The common point between these ants, apart from their evolutionary history which is still 100 million years old, is that they all form societies. Unlike wasps or bees where one finds solitaries, apparently all species of ants are in society. But there are societies of two individuals and societies of tens of millions of individuals. You can well imagine that it is not the same thing.
You also talk about organized chaos… And you say that if we had to compare to man what motivates this common contribution of ants, it could be Wikipedia… Or each one, without being obliged to do so, without being asked by a chef, brings his small stone to the building.
This is without it being planned or organized by a leader actually. Everyone follows a little rule, and it’s those little rules together that bring out something that’s greater than the sum of those little rules. Wikipedia is a good example. There was no need to direct which articles go where… It self-organizes with people who end up doing quite different things. It creates a greater whole than each person could have done individually.
An example: if you look at ants that go out alone to look for food. Researchers had fun tracking the movement of all the individuals leaving the colony. What we see is that each individual goes into a territory that can be 30 meters from the nest and goes hunting in that territory. And when we combine all the territories, it creates a mosaic that perfectly covers the space around the nest. How do they organize this? This is not obvious.
One of the simple little rules is that when an ant finds food, it tends to return to that place. So places where there are already a lot of ants, new ants are not going to find much to eat. There is less food. But also: even if they are from the same colony, an ant used to going into a territory, if it sees one of its naive colleagues wandering around here, it will tend to be a little brutal and say to it: go further. Automatically, with these little rules, it will cover the space around the nest. This is an example of organized chaos.
What are suicide ants?
You find that in the bees… the sacrifice for the colony. These are individuals who end up having enlarged mandibular glands, full of poison, which they are able to relax, causing their body to burst and squirting acid at the enemy, and that can be very efficient. A self-sacrificing ant can kill 3 to 4 and a half individuals. In the end, the balance sheet for the colony is positive.