Ant death spiral

From The Ant Room:

This is one of my favorite things about ants – the ant death spiral. Actually, it’s a circular mill, first described in army ants by Schneirla (1944). A circle of army ants, each one following the ant in front, becomes locked into a circular mill. They will continue to circle each other until they all die.
Ant Death Spiral (Via Cynical-C)



  1. A mechanical means of inducing this behaviour would be far safer and less likely to induce resistance than chemical insecticides.

    “Army ants stripping the flesh from your cattle? Try the new Whamco Super Ant Mill! Only kills enough to solve your problem, without unbalancing the local ecology!”

    1. According to the linked article (which is only short; it’s worth checking out), there is a mechanical means of inducing the mill (in the lab, at least): a glass jar.

      Also, it is possible for the ants to escape.

      For my part, I loved the bit in the article which tells of scientists who produced robots which were programmed to behave like ants – and accidentally produced the death spiral in their robots.

  2. Wow, it seems like natural selection should have produced an instinct in the ants to break out of such a recursive error. Like a pattern in the tiny ant brain that says “ok if you’ve been turning right for several hours and are getting tired… turn LEFT for a little while” or something.

    1. The problem with that is that the colony is the unit that produces the next set of ants. You might get an ant or two that had a mutation that lets them break out of the spiral (I think because I assume that genetic mutation sometimes happens among worker ants), but the queen is the one generating new ants, so that mutation wouldn’t necessarily be passed on to the next colony.

      1. Unless there were a mutation in a queen that caused her to produce workers that were able to break out of the spiral. This could lead to a more successful colony and allow the queen to produce more new queens with the same trait.

    2. The fitness landscape against which creatures are evolving is a changing landscape. What is optimal changes. Evolution doesn’t always evolve in a more positive direction. In fact, evolution can cause the destruction of a species. However, when a species dies, then it’s gone, so we don’t see it. That’s why when we think of evolution we think of the times when it worked. However, this is selection bias — we have a biased view of how evolution works because we tend to see when it worked, and the rest is no longer with us.

  3. Hmmm… I think Godel would have something intelligent to say about this. I think that perhaps you can never design a system built on logical rules that can eliminate the possibility of error. For example, this looks like a perfect natural representation of the fact that you could (provably) never design a compiler that’s good enough to always recognize when code will get itself into an infinite loop.

    God could have kept rewiring that neural network trying to eliminate flaws right up until the seventh-day deadline, but he would never be certain that it might not end up in an infinite loop.

    I do wonder, though, whether Ant Colony Optimization Strategies ever have to deal with this issue. Seems from what I was saying above that they must.

    1. Sam, Godel’s theorems really don’t say anything about this at all. They are a technical set of claims that are often abused by philosophers. If one wanted a math theorem that was relevant to this then one would probably want the Turing halting theorem. This says that it is impossible in general to show that a computer program will never crash. However, even this result is much closer to a technical result that doesn’t precisely apply to this situation.

      1. … So, when Goedel himself applies the Goedelian Formal Undecidability Theorem to philosophy, is it abuse?

        … And is his Formal Ontological Proof* of the existence of a Deity, abuse as well?

        Goedel was highly inclined to answering philosophical questions through the use of logic. Eventually, Ontology, Logic, and Philosophy are really different approaches to the same thing : knowledge.

      2. Actually, Godel’s theorems are very closely related to the Halting Problem. Godel’s First Incompleteness Theorem, for example, can be derived directly from the Halting Problem. Both theorems relate to determining whether certain conclusions can be drawn from a certain set of laws (e.g. is this statement true, will this algorithm halt), and, specifically, that if the laws are complicated enough there will always be problems that are undecidable.

        Likewise (I feel confident to hypothesize), if we have spend a hundred years designing the perfect turing-complete neural network that will power our robotic ant’s brain, we will never know if there might not exist some condition that will cause our poor little robot to enter an infinite loop.

  4. Awesome! I saw smaller one of these in Belize a few years ago, but sadly didn’t have a video camera, so I only got a couple of still pictures.

    1. That was my first thought!
      And in the middle are a couple of whirling dervishes.
      The problem is if all the ants in the world have to visit that backyard once in their lives.

  5. Every simple, effective and efficient system will occasionally spawn absurdities.

    This is as true of instinctive patterns of behavior as it is of any system of laws.

  6. Something vaguely similar to this occurred in my kitchen once when the Argentine ant colony that lives beneath the foundation apparently discovered that there was some spilled frozen juice a the bottom of the freezer. (it seems it had had been left open long enough for one to exit and leave a pheromone trail). So a constant stream of ants entered through a tiny space in the door and became crygenically suspended in an ever increasing pile at the bottom of the freezer. Was pretty spooky.

  7. Isn’t there any way to break it up? Not that there are a shortage of ants in the world, it just seems a bit depressing.

    1. Probably if you threw enough food around the edges, the ants would switch from migration to foraging long enough for the wheel to dispel. I’ve never tried it, though.

  8. This is the way the world ends
    This is the way the world ends
    This is the way the world ends
    Not with a bang but an ANT DEATH SPIRAL.

  9. Makes me want to find my old magnifying glass from when I was a youngin’. I can still smell those ants frying on the sidewalk. *pooF*
    Why does this remind me of a teabagger rally?

  10. I saw one of these in Australia years ago. Of course, it was spiraling in the other direction because it was in the southern hemisphere.

  11. Looks like a Mini-Hajj. I guess self-awareness really is a plus. We can break out of death spirals. Humans 1 Ants 0

  12. to just one of the mikes That’s exactly what I thought, Muslim pilgrims circling about the Ka’bah,but the ants are moving clockwise (do they always?) and the pilgrims move counter-clockwise. Just a strange thought… do not mistake me for one of those anti-Islamic bigots we are hearing from these days.

  13. Do they all die? Or eventually are there a couple of hundred ants climbing over the corpses of their sisters that stop and say ‘hey, maybe this pheromone trail is leading us astray?’.

    Also, if this were a human spiral, there would be a well funded industry of spiral denialists, claiming that the spiral is just part of the natural direction of the swarm, and the left turnists are trying to lead the swarm astray based on faulty evidence. Until there is absolute proof that the endless left spiral is a problem, nothing should be done about it, and suggesting otherwise is tinfoil hat territory.

    1. And many ants would claim there is no spiral, only a straight line; If they were in a spiral everyone would eventually collide at the center, right, so it can’t possibly be a spiral, but can only be the most awesome trail to bounty and providence ever.

      Given that worker ants sometimes have a tendency to develop into queens if separated from the pheromones of their queen for an extended period of time, a mutation that caused ants to break out of such spirals (effectively, break away from the colony’s commands and set out on their own) would have some interesting consequences … I can foresee colonies of army ants that, instead of following an easily-deducible migration pattern and beginning in a short time span, randomly crop up throughout their active season. Kill the queen and it’s like a hydra.

      1. Given that worker ants sometimes have a tendency to develop into queens if separated from the pheromones of their queen for an extended period of time…

        Do they? Larvae certainly are raised to become queens when one is missing, but I’ve never heard of this in adults, even reading through The Ants by Wilson. Is it something that happens in all species? Ant wheels generally only occur in army and river ants.

  14. Looks like Burning Man to me.

    Heard a lecture by an Ant Biologist who had isolated all the different chemical signals that ants communicate with, and synthesized analogues. As I remember, one gram of one of the chemicals was the equivalent of all of that chemical that would be produced by all of the ants in the entire world in one year, and any ants exposed to the concentrate would, as seen here, repeat whatever action the chemical specified, until they died.

    Like I said, looks like Burning Man to me.

  15. Thank you for bringing this defect in ANT 1.96
    to our attention. Please accept our apologies
    and know that we will do everything possible to
    correct this defect in ANT 2.0.

    The ANT Development Team

  16. * not an actual proof of the existence of anything other than Goedel’s belief in a deity. Proof commits a categorical error in positing that simply because humans find something aesthetically pleasing there must necessarily be an independent gestalt entity comprised purely of all that humans find most aesthetically pleasing and that entity is a deity.

  17. Mighty impressive. I wonder how you can derive power from an ant mill. If they were oxen you could harness each of them or use their weight to drive a wheel but ants are too small to harness and too light to use their weight to drive anything.

  18. But seriously, what if you did just blow them around for a while with a hair dryer or leaf blower? Would they reform like T-1000? OR just go their merry way?

  19. wow. those ants are replicating each others behaviour.
    Beleive me, if I could have worked in ‘electric’, I would have.

  20. Like the Extreme Right Wing who are being lead astray, they stay amongst familiar selves and constantly circle the perimeter to guard against encroaching evil, leading to their death.

  21. *hurk*

    -abs apologizes, but he needs to go scratch his head frantically, and after that most of the rest of him as well, watchning that makes him itch (and yes, he knows it’s psychosomatic, that doesn’t make it not real)

  22. This inevitable behavior prevents overpopulation. were they all to die, others would surely survive, and feast on the new corpse-y foodstuffs located conveniently right outside the front of the anthill.

  23. what really happened here is that at the quarterly information meeting someone forgot the tps reports and consequentially due to the ants evolutionarily retarded nature regressed to a nexus point where draconian orthodox judeo-christian and fundamentalist islamic dogma intervened with each others and resulted in the ants not only stoning the absentminded fellow in charge of the tps reports but finished out the day with a healthy queen gangbang and a relaxing cigarette. Unfortunately for the ants, only to date have humans created cigarettes and in their fervor to hold the mammoth stub high enough to light, caused an accident involving a magnifying glass, some bubblegum and a toothpick. the casualties numbered in the hundreds but the true horror lie in the now malformed colony of ants; each of whom had lost all three right legs and were doomed to an eternity of walking only right, never left. and that is what happened here

  24. It looks like NASCAR. Too bad the result of humans driving in endless circles doesn’t share the romantic conclusion of these ants.

  25. I love how most humans feel that this is an ‘error’ of some sort. There are not ‘errors’ in real life. Everything has a purpose.

    Eventually, one of the ants will mutate into a queen and they will form a new hive, or a soldier will begin a stronger scent trail and begin a new search for the hive, perhaps leading an attack on to a closer enemy hive.

    And, even if they do die off, what gives you the right to judge that it is ‘wrong’ or ‘a waste’? Perhaps it is needed for that colony to thin their numbers, etc etc

    1. They die off. Scientifically demonstrated, as I understand.

      You might have a different attitude if the species were your own, and it happened to be acting stupidly, about to destroy itself. One has to imagine oneself amidst a holocaust to realize the reality of the horror, but, then again, that is very hard to do. Perhaps that’s why we have such behavior. I’m not so sure I buy the “everything has a purpose” idea. If the entire species of humans kills itself (perhaps by introducing toxins to the environment that cause us to evolve in a very negative way), it might make things easier for other species on our planet. Is that the kind of purpose you had in mind?

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