No ant left behind: Ants carry injured comrades back to the nest and tend to their wounds

This is a science post, and if you don’t read it I’ll shoot this kitten:

Today we learn of an amazing behavior of termite-hunting ants, who carry their wounded comrades back to the nest and tend their injuries, licking them in a way that appears to heal them. It’s the first time that anybody’s shown “social wound treatment” in ants. The paper, by Erik T. Frank, Marten Wehrhahn and K Eduard Linsemair, appears in the new Proceedings of the Royal Society B (reference at bottom, free access, and pdf here).

Remember when you read this that these are haplodiploid organisms, which means that males have a half set of chromosomes produced from the queen’s unfertilized eggs, and, further the diploid female workers who raid the termite nests are sterile. They’re all sisters: daughters of the queen and the single male she’s presumably mated with.

The species at hand is the ant Megaponera analis, a termite-eating specialist found in sub-Saharan Africa.  A column of 200-600 ant raiders leaves the nest, heads for a termite colony underground, breaks it open, collects the termites for food, and carries them back to the nest. Because termites aren’t unprotected—they have “soldiers” with huge heads and formidable biting mandibles—some of the ants get hurt on these raids. Their legs and other bits get chomped off, and termites even clamp onto the ants with their jaws, with the ants running about with a termite attached to them.

An injured ant releases “alarm” pheromones—dimethyl disulfide and dimethyl trisulfide—from a gland on their head. This attracts the other ants. Here’s a video showing an injured ant attracting its nestmates and then being carried back to the nest.

The carried ants become quiescent and compliant, tucking their legs underneath the body—almost like a kitten being carried by its mom. The injured ants are tended in the nest, with other ants actually cleaning the wound with their mouthparts (the ants can easily get infected from bacteria in the soil or from the termites). They also try to remove any termites clinging to the ants, and this can take up to several hours.

The authors did a number of experiments that involved artificially injuring ants, either lightly (2 legs removed) or severely (5 legs removed). Of 20 ants in each class, 45% of the lightly injured were taken back to the nest (this is on the return journey from the raid), while only 5% of the severely injured ant were (that is one ant). This, of course, is an adaptive behavior, as four-legged ants can survive and raid in the future, while one-legged ants can’t do squat.

Ants who have lost more than three legs are never found in the nest, and, as I said, those with five legs artificially removed (I have to say, I don’t like hurting insects this way) are rarely brought back to the nest. There’s some evidence that lightly injured ants may exaggerate their injuries, flailing about when nestmates are nearby, though as soon as they’re touched by the antennae of a nestmate, this behavior ceases and they curl up for carrying. If the lightly injured are not discovered and carried back, they trot back on their own.

To see if ants were actually counting the legs of the injured, the experimenters crushed the legs without removing them, rendering the legs unusable. Again, those with five injured legs (which were still attached) were ignored by their nestmates and left to die, while those with only two were carried back and tended. Ants with two legs can apparently function well, even participating in raids, while those with more legs injured are useless to the colony. The ants apparently discriminate between the lightly and severely injured not by counting but by the behavior of the wounded: those with a number of injured or removed legs can’t right themselves, and fling themselves about in an attempt to do so. Ants that do this aren’t picked up (they may be harder to pick up anyway). This is a form of insect triage.

Here’s a video of an injured ant whose leg wound is being cleaned:

How effective is this cleaning? Some experiments compared the mortality of artificially injured ants (two legs removed) when they were tended by their nestmates for either 1 or 12 hours (two treatments), and also when they were placed on sterile soil after injury as well as on unsterile soil, and also the mortality of control (unmanipulated) ants. Here’s the curve of mortality for all the five treatments. As you can see, injured ants placed on nonsterile soil die quickly, while being placed on sterile soil, being uninjured, being injured, or having only a one-hour treatment results in survivorship as high as in the controls—in fact, there’s no difference among these four classes. It looks, then, as if it’s nonsterile conditions that cause mortality, implying that ants in the nest, besides removing debris, may well be applying some anti-microbial substance to the wound. I suspect this is the case, but we don’t have evidence yet.

Now remember that the injured ants, like their nestmates, are STERILE. Saving them, it would seem, doesn’t help anybody propagate their genes, so if this rescue behavior is evolved, as it almost certainly is, what is the selective advantage?

The answer is probably this: since injured ants are numerous compared to the size of the colony, any ant who saves its nestmates allows the colony to flourish better (the rescued can function in the colony), and that helps the queen, who shares half of the workers’ genes. In other words (and as Darwin surmised) even if you’re helping a sterile worker, you’re giving a marginal reproductive advantage to the only reproductive female: the queen.

But how much of an advantage can that be given the size of the colony? Is saving one ant going to make any difference to how well the queen does? The answer involves three considerations. First, this evolution is more likely to happen in a smaller rather than a larger colony, for in the former case each ant constitutes a larger fraction of the population than the latter, giving the queen a larger marginal advantage. (There could also be some “colony selection” here—a form of group selection—but its efficacy requires that we posit differential extinction of entire colonies based on whether or not they contain “nursing” workers.)

Second, if injured ants nearly always died, there would be little advantage to tending them. But the tended ants are the lightly injured ones, and survive as well as uninjured ants. Those who are more severely injured are left to die.

As the authors note, however, Megaponera analis has small colonies and the rescued ants nearly all survive; the species thus “fits all the criteria where a rescue behavior focused on injured ants has a large benefit for the colony”.

Finally, if the behavior first showed up in just a single mutant worker, the advantage to the colony would be small. What’s more likely is that the queen herself or her haploid mate contained the first mutation for helping. The male, who doesn’t undergo meiosis, would pass it on to all the colony’s workers (assuming females mate but once and store sperm); the female to half the workers. Either way, a mutant gene for helping might first show its effects in a large fraction of the colony’s workers, thus tremendously boosting the evolutionary advantage of the queen who contained that mutant and produced helpful workers.

h/t: Matthew

________

Frank, E. T., M. Wehrhahn, and K. E. Linsenmair. 2018. Wound treatment and selective help in a termite-hunting ant. Proceedings of the Royal Society B: Biological Sciences 285. DOI: 10.1098/rspb.2017.2457

136 Comments

  1. Joseph McClain
    Posted February 16, 2018 at 10:34 am | Permalink

    Reading it now! Put the gun down and walk away!

    • Joseph McClain
      Posted February 16, 2018 at 11:01 am | Permalink

      Every ant can’t reproduce, so don’t we have to even think hard about terms such as “individual” when it comes to considering selective advantage? It’s fascinating that these ants have developed the ability to rescue, heal — and execute what can only be called triage. Plus, there is even malingering. Sheesh.

      • darrelle
        Posted February 16, 2018 at 1:23 pm | Permalink

        I wonder if it makes any sense to consider the entire colony as an extended part of the queen. All reproduction is through the queen and if the queen dies the colony dies. All of the other ants seem to be evolved to provide for the queen and her reproductive activities. So perhaps for considerations of selection it makes sense to think of the queen as the organism and all the other ants as evolved features of the queen.

        Probably not!

        • David Coxill
          Posted February 16, 2018 at 2:29 pm | Permalink

          Perhaps they are like Bees ,if the Queen dies the hive knows she is dead by the pheromone she no longer gives out ,so one of the other females takes her place .

          Might have that wrong ,most of the things i think i know turn out to be wrong .

          • gravelinspector-Aidan
            Posted February 16, 2018 at 3:31 pm | Permalink

            I have heard of that sort of behaviour, but doesn’t that imply that is a situation where any female can become a queen and is prevented by some chemical from the existing queen. Whereas for ants (and/ or bees, I’m not entirely sure), the default development programme is to sterile worker and a particular compound is needed to render eggs capable of gaining fertility.

        • Posted February 16, 2018 at 3:35 pm | Permalink

          That’s something I’ve thought about myself.

          Consider bees that lose their stingers and die when they sting. It seems to me that they didn’t evolve to survive and reproduce, rather, the queen evolved to produce them so that the queen would survive and reproduce.

          But that’s just uninformed speculation on my part.

    • Gamall
      Posted February 16, 2018 at 12:27 pm | Permalink

      I don’t like kittens.

      But I like ants, so I read it anyway. 😐

      • loren russell
        Posted February 16, 2018 at 6:00 pm | Permalink

        About the photo: how many think it is cute? adorable? ironic? OK as long as the gun is unloaded?

        How many saying yes to one of those categories would answer the same if a human infant were substituted for the kitten?

        If a disparity, would we learn anything about our human-first instincts?

        • Posted February 27, 2018 at 4:40 pm | Permalink

          I’d definitely prefer a photo of the kitten without the gun.

    • rickflick
      Posted February 16, 2018 at 3:13 pm | Permalink

      sub

    • Posted February 16, 2018 at 3:16 pm | Permalink

      And put it where the kitten can’t reach it; its suicidal tendencies are well-documented.

      • harrync
        Posted February 16, 2018 at 4:47 pm | Permalink

        I had a roommate who got a cute little kitten. He refused to name it; I named it Susie-cat, short for suicidal kitten. Wherever you walked, you almost certainly would step on her if you weren’t careful.

  2. Posted February 16, 2018 at 10:38 am | Permalink

    Why anyone would not think the universe is determined after reading this is crazy. Extraordinary behavior from such a small set of neurons. In comparison to ants, humans seem so inefficient with their massive heat mongering brains.

  3. Barry Lyons
    Posted February 16, 2018 at 10:45 am | Permalink

    What a fantastic report! But has anyone written a book about altruism and such among all sorts of animals? I would read that.

    • gravelinspector-Aidan
      Posted February 16, 2018 at 3:34 pm | Permalink

      If it benefits genes that are also in your body, it’s not altruism. Dawkins, basically the whole of the “Extended Phenotype” ; Haldane (fils) and his after-diner line about sacrificing himself for four cousins or eight second cousins.
      Are you the unit of selection, or is it your genotype?

    • rickflick
      Posted February 16, 2018 at 7:41 pm | Permalink

      E. O. Wilson is an ant expert and wrote wonderfully about them. The group selection idea is one he favors. What we see here may be “a form of group selection”, which is probably why Wilson likes the idea.
      ‘The Ants’ is a zoology textbook by the German entomologist Bert Hölldobler and the American entomologist E. O. Wilson, first published in 1990. It won the Pulitzer Prize for General Non-Fiction in 1991.

  4. Posted February 16, 2018 at 10:46 am | Permalink

    I have started reading. Tell you what though Professor Coyne: Nice try. You’d never shoot a kitten. 🙂

    • Posted February 16, 2018 at 10:49 am | Permalink

      You found me out!

      • walkingmap
        Posted February 16, 2018 at 11:05 am | Permalink

        You wouldn’t even shoot a fruit fly as there would be nothing left to dissect. 🙂

      • David Coxill
        Posted February 16, 2018 at 2:31 pm | Permalink

        So you were bluffing all along ,you rotten egg you.

    • Heather Hastie
      Posted February 16, 2018 at 5:22 pm | Permalink

      Exactly! Anyone who believes Jerry would ever shoot a kitten is deluded!

      I read this because it sounded really interesting, which it was.

      (And I put a comment because then it will count as two visits to the page instead of just one.)

  5. Simon Hayward
    Posted February 16, 2018 at 10:47 am | Permalink

    I don’t think I’ve ever seen a 24 hour Kaplan-Meier curve before. I’m more used to multiple years and occasionally decades for human data and weeks/months for mice.

  6. Posted February 16, 2018 at 10:48 am | Permalink

    If I give in to your threats, aren’t I just encouraging terrorism?

    • wills
      Posted February 16, 2018 at 11:20 am | Permalink

      and that would be a catastrophe.

      somebody had to say it… right?

      • gravelinspector-Aidan
        Posted February 16, 2018 at 3:36 pm | Permalink

        Purrrfect response.

  7. Posted February 16, 2018 at 10:53 am | Permalink

    Absolutely fascinating!

  8. Posted February 16, 2018 at 10:59 am | Permalink

    “There’s some evidence that lightly injured ants may exaggerate their injuries”

    I suspect that since all are genetically identical, there is no selective advantage to dishonest signaling, so the exaggeration is not intended to deceive but to inform….

    • Posted February 16, 2018 at 11:00 am | Permalink

      Yes, good point. But it’s still perhaps an exaggeration of how bad off they are, though not evolved as a deception.

      • colin
        Posted February 16, 2018 at 12:00 pm | Permalink

        Or lightly injured ants are more able to signal vigorously than severly injured ones.

        • Posted February 17, 2018 at 1:30 pm | Permalink

          Yes, that would be honest signalling.

          • rickflick
            Posted February 17, 2018 at 5:45 pm | Permalink

            As opposed to honesty signalling.

      • W.Benson
        Posted February 16, 2018 at 12:08 pm | Permalink

        There is, I bet, natural selection at the colony level against exaggeration of injury in worker ants, but not against strong signaling that helps draw the attention of nestmates. A colony bearing genetic beggars that cause injured ants to fake mild injury ‘to’ save themselves would waste time and energy that the colony could invest in reproduction caring for excessively injured ants. This could probably be investigated experimentally, but it wouldn’t be easy.

      • Posted February 27, 2018 at 4:46 pm | Permalink

        I wonder, however, why they would exaggerate the injury, if ants with really severe injuries are left to die. Perhaps they are just attracting attention (cf. a human screaming in pain vs. one calling for help – they could be mistaken by observers from another species).

        BTW, I have been taught that in a case of nuclear explosion, we should tend to the lightly injured rather than to the severely injured who would be doomed anyway.

    • W.Benson
      Posted February 16, 2018 at 12:17 pm | Permalink

      There is, I bet, natural selection at the colony level against exaggerating injury by worker ants, but not against strong signaling that helps draw the attention of nestmates. Sometimes an injured ant cannot evaluate its level of injury and future use to the colony. Also, as colin says, lightly injured ants may be able to signal more vigorously. A colony bearing genetic beggars that fake mild injury ‘to’ save themselves would waste time and energy that the colony would otherwise invest in reproduction. Such a trait would tend to be weeded out by selection. The question of selection pressure could probably be investigated experimentally, but it wouldn’t be easy.

      • Posted February 16, 2018 at 12:26 pm | Permalink

        Exaggerating injury would only be selected against if the nurses are in short supply or their nursing prevents them from doing something else beneficial to the colony. Of course, if all ants start wanting free rides back to the colony, that would be bad.

        • W.Benson
          Posted February 16, 2018 at 8:22 pm | Permalink

          Rescued ants also eat food that would otherwise go to brood, colony growth and ultimately reproductive success (production of new winged queen ants). If a class of injured ant can’t pay its way, selection should favor colonies with workers that deny these injured ants aid. This seems to be what happens.

  9. glen1davidson
    Posted February 16, 2018 at 10:59 am | Permalink

    Finally, if the behavior first showed up in just a single mutant worker, the advantage to the colony would be small.

    More importantly, it wouldn’t be passed on to any offspring.

    Glen Davidson

    • W.Benson
      Posted February 16, 2018 at 12:23 pm | Permalink

      Beat me to the comment! On the other hand worker ants sometimes lay unfertilized haploid eggs that develop parthenogenetically into males.

  10. Ken Kukec
    Posted February 16, 2018 at 11:02 am | Permalink

    Goin’ all National Lampoon & Cheeseface on us, huh, boss?

    • Posted February 16, 2018 at 11:33 am | Permalink

      Not enough nudity.

    • Posted February 16, 2018 at 12:21 pm | Permalink

      I was going to mention…
      Those of a certain age may know about ‘… or we will shoot this dog!’

    • David Coxill
      Posted February 16, 2018 at 9:07 pm | Permalink

      Did someone really track the dog down and kill it?

  11. DrBrydon
    Posted February 16, 2018 at 11:02 am | Permalink

    I am not a huge fan of bugs, and maybe I am getting squeamish in my old age, but the idea of purposefully crushing an ant’s leg seems wrong.

    • Kiwi Dave
      Posted February 16, 2018 at 2:32 pm | Permalink

      That was my reaction too, yet last night I squashed without a moment’s thought at least 50 ants trekking to and from a near invisible speck of food on the floor, though they weren’t doing any harm. So, why the different reactions, especially when the science was quite interesting?

    • harrync
      Posted February 16, 2018 at 5:02 pm | Permalink

      You know, those ants were going out to EAT termites. Nature is cruel, whether ants or human experimenters. Besides that, the human scientists had no free will.

    • Posted February 28, 2018 at 8:27 am | Permalink

      Agreed. Deliberately removing and crushing the legs of these ants (or any animal) for this experiment does not, to me, seem justifiable, no matter how interesting the results.

  12. GBJames
    Posted February 16, 2018 at 11:04 am | Permalink

    sub

  13. Randall Schenck
    Posted February 16, 2018 at 11:12 am | Permalink

    I have to think this is a part of evolution in the ants just as similar changes have taken place in humans. We did very little when soldiers were wounded during the revolutionary war and then improved a bit during the civil war but not much. During WWI and then WWII more was done and medics were added to the force. During Korea it continued to improve and so on.

    • DrBrydon
      Posted February 16, 2018 at 11:24 am | Permalink

      Interesting point. Of course, until reliable anesthetics were available, there was little a surgeon could do for many wounded. Also critical was the development of techniques for vascular transplants, for which Alexis Carrell won the 1912 Noble Prize for Medicine. (There is an interesting book about Carrell’s later work with Charles Lindbergh on the prolongation of life called The Immortalists).

      • Posted February 16, 2018 at 11:30 am | Permalink

        It was the development of the germ theory of disease that is responsible for the improved survival rates of combatants – and everyone else as well. Improved surgical and medical techniques in the latter part of the 20th century helped even more, but understanding infection and how to prevent and treat it did far and a way more than any other medical development.

        • glen1davidson
          Posted February 16, 2018 at 11:52 am | Permalink

          Antibiotics!

          Glen Davidson

          • Posted February 16, 2018 at 12:07 pm | Permalink

            Sewers!

          • busterggi
            Posted February 16, 2018 at 12:08 pm | Permalink

            So much more effective than thoughts & prayers.

            • Posted February 16, 2018 at 12:28 pm | Permalink

              Except thoughts about making antibiotics and sewers! The prayers are still worthless.

          • gravelinspector-Aidan
            Posted February 16, 2018 at 4:42 pm | Permalink

            Antisepsis – it was around for about a half century before antibiotics, and sufficiently effective that surgical survival rates increased to the point that people would actually choose to have surgery for non-life-threatening conditions.

  14. p. puk
    Posted February 16, 2018 at 11:13 am | Permalink

    It’s my girlfriends birthday and we’re getting ready to leave for a naughty weekend so I have no time to read the article before we arrive at the destination.

    SO PLEASE DON’T SHooT THE KITTEN YET, M’KAY?

  15. Howard Neufeld
    Posted February 16, 2018 at 11:18 am | Permalink

    First – don’t shoot the kitten. Excellent article, and very interesting behavior by the ants.

    If the effect is more pronounced when injured ants make up a substantial proportion of the colony population, couldn’t you hypothesize that there is a size limit beyond which this behavior is no longer adaptive?

  16. David Fuqua
    Posted February 16, 2018 at 11:27 am | Permalink

    Good stuff!

  17. ThyroidPlanet
    Posted February 16, 2018 at 11:30 am | Permalink

    Sub before reading

  18. nicky
    Posted February 16, 2018 at 11:31 am | Permalink

    Jerry, you won’t shoot a kitten, ever, I know that, but even the hollow threat appears to show that the gun-nuts have gone to your head.
    Highly interesting, and especially that it is predictable for small colonies, and observed in small colonies. The benefit of saving a worker must be greater than the energy ‘lost’ in tending.
    I cannot really understand that some lightly wounded ones ‘pretend’ to be worse off than they are. It can’t be ‘deception’, since all are sterile. Maybe lightly wounded ones, with a good chance of survival have an even better chance if tended to?
    Note, I root for the termites 🙂

  19. Neil Wolfe
    Posted February 16, 2018 at 11:32 am | Permalink

    Instead of shooting the kitten try ripping off one of its legs to “lightly injure” it. I’m sure some other cats will come along to take care of it.

    • Posted February 16, 2018 at 11:59 am | Permalink

      Yes, I have qualms about any research that involves deliberate injury. I came across some recently that involved reproducing the effect of cauliflower ears in rabbits by dropping weights onto the ears.

      • Posted February 16, 2018 at 12:51 pm | Permalink

        What about research that involves the use of mice in developing cancer therapies? This work necessarily inflicts deliberate injury, often painful and always fatal on the animals. Do you have qualms about that kind of work?

  20. Posted February 16, 2018 at 11:36 am | Permalink

    I have complied.

    • Posted February 16, 2018 at 12:08 pm | Permalink

      Do not like the idea of the insects beeig hurt.

  21. glen1davidson
    Posted February 16, 2018 at 11:43 am | Permalink

    The gun is no match for kitty’s cuteness.

    Glen Davidson

  22. Posted February 16, 2018 at 11:47 am | Permalink

    Fascinating. How often did “help the other with an injury” evolve, then?

  23. Posted February 16, 2018 at 11:52 am | Permalink

    “There’s some evidence that lightly injured ants may exaggerate their injuries, flailing about when nestmates are nearby” – sort of like footballers!

    • Posted February 16, 2018 at 12:02 pm | Permalink

      • Posted February 16, 2018 at 12:04 pm | Permalink

        Of course there is a selective advantage to the team here in theory in the ‘dishonest signal,’ although there could be an element of disadvantage in gaining a reputation for exaggeration, something that ants will not acquire!

        • boggy
          Posted February 16, 2018 at 12:41 pm | Permalink

          Any relation to Norbert (‘Nobby’) Stiles.

          • Posted February 19, 2018 at 5:58 am | Permalink

            Nope – but back in the 70s we got a phone call from Switzerland from some club trying to track him down…!

      • Posted February 16, 2018 at 12:26 pm | Permalink

        Hilarious. The voiceover about comparing soccer to American football is barking up the wrong tree. Compare Am. football to rugby. Rugby is not for the faint of heart.

      • nicky
        Posted February 16, 2018 at 11:01 pm | Permalink

        Note, faking an injury may lead to an opponent to be sent off. However, it is not without risks, if the referee recognises it is fake, the faker can get a red card himself.

  24. organism
    Posted February 16, 2018 at 11:52 am | Permalink

    I love these science posts. Whenever I see a science post, I’m commenting!

  25. Posted February 16, 2018 at 11:56 am | Permalink

    My guess is that this behaviour is related to carrying prey back to the colony…

    • darrelle
      Posted February 16, 2018 at 1:33 pm | Permalink

      Before reading the article and verifying that the study included study of the final dispositions of injured ants, my first thought was, “are they sure the injured ants aren’t being taken back to the larder?”

      • Posted February 19, 2018 at 5:59 am | Permalink

        Yes – but it could be triggered by stimulus –
        using the same ‘neural pathway’ ?

  26. Posted February 16, 2018 at 12:00 pm | Permalink

    Very interesting. Evolution is amazing.

  27. Paul S
    Posted February 16, 2018 at 12:01 pm | Permalink

    Kitteh wins the fight, as always. Great post, I wonder if this experiment will be done on other ants and different colony sizes.

    Is it possible that larger colonies have the help me mutation but don’t act on it because it isn’t necessary for their survival?

  28. Posted February 16, 2018 at 12:06 pm | Permalink

    Very interesting post!

    The kitten appears to have short ears like Gus. Coincidence?

    Do you believe “differential extinction of entire colonies based on whether or not they contain ‘nursing’ workers” is a stretch?

  29. onychomys
    Posted February 16, 2018 at 12:10 pm | Permalink

    I clicked through from my RSS reader just so my vote for science posts could be recorded.

  30. Posted February 16, 2018 at 12:11 pm | Permalink

    No need to shoot the kitty.

    I always find it hard to get my mind around the unit of selection in ants and bees. The workers aren’t being favored (or not) by natural selection. It’s the queens. Queens who produce workers who rescue each other (in small colonies) leave more offspring than queens who don’t. Mutations in workers are about as useful evolutionarily as somatic mutations in humans.

  31. Posted February 16, 2018 at 12:18 pm | Permalink

    Yes, that is fascinating! I read an article about this a couple of days ago:

    https://news.nationalgeographic.com/2018/02/matabele-ants-rescue-heal-injured-soldiers/

  32. Posted February 16, 2018 at 12:29 pm | Permalink

    Very interesting!
    I wonder if ant saliva has a blood anticoagulant property. Loss of water would be super-deadly to these small creatures.
    Also, I am sure that many of us have seen ants carry off an injured worker to their nest. I know I have, and now I wonder what that is about.

    • darrelle
      Posted February 16, 2018 at 1:36 pm | Permalink

      I always assumed it was “waste not want not.” Looks like I may have been uncharitable to ants, at least to some ants, since I was a kid.

  33. davidintoronto
    Posted February 16, 2018 at 12:30 pm | Permalink

    Read the post (fascinating); saved a kitty.

  34. Jacques Hausser
    Posted February 16, 2018 at 12:31 pm | Permalink

    The amount of wounded ants in hunting parties is up to 20% (if I remember well) while it is only about 5% in the colony as a whole. What means that after their misadventure, hunters (old ants) do not turn themselves back towards secure activities like housekeeping or nursing larvae, but continue their dangerous life. The authors suggest that the division of work, linked to the age, is well ingrained genetically. It would be interesting to compare the efficiency of previously wounded hunters and intact ones.

  35. d McCallum
    Posted February 16, 2018 at 12:42 pm | Permalink

    I have terrible cat allergies so blast away.
    As far as reading the science articles ,they just come up on my browser. Full article, no clicking necessary. How would you determine What I am reading unless I tell you that four legged ants are saved but one legged ants are left as fertilizer.??

  36. prinzler
    Posted February 16, 2018 at 12:47 pm | Permalink

    I think you’re bluffing!

    P-TTTNG

    No, you weren’t bluffing.

  37. Mark R.
    Posted February 16, 2018 at 12:55 pm | Permalink

    A complex program in a very small brain. Amazing.

    Maybe I didn’t read it closely enough, but does this behavior occur in all colonies of Megaponera analis?

  38. Cate Plys
    Posted February 16, 2018 at 12:56 pm | Permalink

    The thing about the ants who exaggerate their injuries that I don’t entirely understand is this: The other ants won’t save the catastrophically injured. So wouldn’t it make more sense for them to pretend to be in better shape than they really are?

    Note: I almost always read science posts but almost never have a worthy comment, so I’m not normally counted as a science post reader. This comment is not necessarily worthy either but I was determined to be counted today, if only to save the kitten.

    • busterggi
      Posted February 16, 2018 at 1:28 pm | Permalink

      Id guess the individual pheramones may vary by severeness of injury and this may be a secondary signal for help – note they cooperate when help is offered unlike those with fatal injuries.

    • W.Benson
      Posted February 16, 2018 at 6:29 pm | Permalink

      Ants, excepting males and queens, do not do what is best for them as individuals. Worker ants are selected to work and sacrifice themselves for the reproductive well being of the colony, or better, of the queen, who is the agent that transmits worker genes. It is thus better for an injured ant to accurately inform its condition so that it is only saved by comrades (!) if saving it contributes to the reproductive success of the colony.
      Nothing in social behavior makes sense except in the light of sociobiology.

  39. Sixtus
    Posted February 16, 2018 at 1:04 pm | Permalink

    “One-legged ants can’t do squat.” Maybe they can do deadlifts. (Sorry, I couldn’t resist.)

    • Janet
      Posted February 16, 2018 at 1:21 pm | Permalink

      Well, that’s funny!

    • busterggi
      Posted February 16, 2018 at 1:29 pm | Permalink

      Frog with no legs goes deaf.

  40. µ
    Posted February 16, 2018 at 1:44 pm | Permalink

    If the experimenters indeed injured the ants deliberately by cutting off legs, this seems poor science, for ethical reasons.

    The experimenters seem to have violated the research-ethics guidelines for the ethical treatment of animals, which are posted here
    https://royalsociety.org/journals/ethics-policies/research-ethics/

    These guidelines require that studies published in ProcRoyB “studies must follow the Association for the Study of Animal Behaviour / Animal Behavior Society”, which are here:
    https://www.elsevier.com/__data/promis_misc/ASAB2006.pdf

    If the leg amputations were deliberate by the researchers (I can’t access the original publication to read the Methods), it seems Prof. Linsenmair should be ashamed for endorsing this research in his lab.

    • loren russell
      Posted February 16, 2018 at 2:55 pm | Permalink

      MR MU: There was a minority report from the termites that criticized the researcher for not pulling all the legs off all the ants.

    • Posted February 16, 2018 at 3:56 pm | Permalink

      Nonsense. You posted those links but it is clear you are someone who isn’t familiar with how animals may be used in research.

      • µ
        Posted February 16, 2018 at 9:34 pm | Permalink

        mikeyc: Did you read he guidelines by he Animal Behaviour Society (second link), particularly the section on Procedures on page 303?

        Also, this is what I do, research on ants, for the past 30 years. On the grant-review panels that I attend, a research proposal with this kind of mutilation of ants (crushing legs and such) would be rejected by the panel.

        • Posted February 28, 2018 at 8:31 am | Permalink

          “..a research proposal with this kind of mutilation of ants (crushing legs and such) would be rejected by the panel.”

          And rightly so! I’m glad to hear it’s not just the non-biologists among us who are deeply uncomfortable with the treatment of the animals this particular study

        • GBJames
          Posted February 28, 2018 at 8:51 am | Permalink

          Do the panels you reference also block the use of Drosophila experiments that kill files?

  41. BobTerrace
    Posted February 16, 2018 at 1:49 pm | Permalink

    Read (past tense – rɛd/)

  42. gluonspring
    Posted February 16, 2018 at 2:26 pm | Permalink

    Even though I knew you wouldn’t shoot a kitten, the graphic was still effective in getting me to stop and take time to read the article.

    I wonder what fraction of ants get injured in any given raid? And how frequent are raids (that is, how many ants are injured in a given time frame)? How does that compare to the rate that new ants hatch? Of course, it probably takes more energy to make a new ant than to clean one the hatch rate is likely only relevant if they are injured at a rate that can’t be replaced.

    I tried to go to the article to see if it had answers to these questions, but the full text link doesn’t work for me, it just gives a way to buy, subscribe, or login.

    • Posted February 17, 2018 at 10:09 pm | Permalink

      And I had the opposite reaction- to delibertely not read the article until now.

  43. Posted February 16, 2018 at 2:35 pm | Permalink

    Fascinating. I think we get a much better understanding of mysteries like altruism when we observe it in social insects.

  44. Posted February 16, 2018 at 2:49 pm | Permalink

    Very interesting.

  45. Brad
    Posted February 16, 2018 at 3:45 pm | Permalink

    Very interesting article about ants. But I am still up-set about the kitten. Even the threat of violence seems obscene to me now. That comes from an old soldier that served in a MASH unit in Vietnam & later as combat battalion medical officer on three continents. I understand that it was meant to be funny, but …….

  46. drew
    Posted February 16, 2018 at 4:01 pm | Permalink

    Darnit, I clicked on the link before I read the first line.

    😉

  47. Graham Martin-Royle
    Posted February 16, 2018 at 4:12 pm | Permalink

    Okay, let the kitten go, I read the article.

  48. Hempenstein
    Posted February 16, 2018 at 5:19 pm | Permalink

    I assume that the colony has invested a certain caloric input into each worker – feeding the larvae. If that’s right, then there’s the caloric value of the raid to be considered. If the injured ants were all left to die and on average together represented 100calories they’d have to bring more than 100C worth of termites back to make the effort energetically worthwhile.

    My guess is that the balance without ambulance service is energetically marginal, and the medic attention is what enables them to dine on termite.

    My guess is there’s some of this in the Discussion of the paper, but I couldn’t get into the PDF without registering for a free trial.

    • Hempenstein
      Posted February 16, 2018 at 5:42 pm | Permalink

      I was trying to think of how a calculation would work, but I was basing it per ant and gave up.
      But if the average lifetime of an ant is one year, 100 ants go on each raid, and they make 50 raids in a year, the replacement value of one ant is (say) 5calories, three ants are lost in each raid (and three are saved each time too), and the average caloric value of a raid is 40calories, then a year’s worth of raids brings in 2000calories, against a loss of 750 calories of ants in that year, so the colony has 1250calories to work with during the year excluding other caloric input. But they need 500calories just to replace the colony annually, so now we’re down to 750C to spend on other things like their own metabolism. If no ants were saved each time, the colony qualify as an energetic nonprofit agency, and since they need calories for other things, not rescuing injured ants doesn’t work.

      • glen1davidson
        Posted February 16, 2018 at 5:57 pm | Permalink

        Which makes me wonder why only 45% of lightly injured ants are saved.

        There could be very good reasons, like it might usually be rather dangerous, or maybe older ants aren’t worth the trouble. But 45% isn’t exactly a high rate, and it would be interesting to know why not even half of lightly injured ants are saved. Future research, probably.

        Glen Davidson

        • Posted February 16, 2018 at 6:02 pm | Permalink

          Sampling error is probably the main reason. The “n” of 20 is likely (much) too small.

        • Hempenstein
          Posted February 17, 2018 at 9:48 am | Permalink

          Suspect it’s the time factor & risk/reward. The more injured, the more time needs to be spent on the field of battle, and the greater the chance of winding up with (using the above hypothetical values) the colony being down 10 calories vs. five rescued.

  49. pdx1jtj
    Posted February 16, 2018 at 6:12 pm | Permalink

    sub

  50. ladyatheist
    Posted February 16, 2018 at 6:15 pm | Permalink

    It’s curious that several ants investigate the injured ant before one took it home. Was that the male? Or did the investigating ants give off a tiny bit of some pheromone until a critical mass of it had been released?

    I couldn’t crush their legs, either, but I could stomp on them. Weird.

  51. Posted February 16, 2018 at 6:26 pm | Permalink

    Interesting article (thanks for the write-up!) and interesting comments regarding the experimental treatment of the ants.

    I find the general issue both very sticky and quite fascinating. Science and society have long ago entered into a kind of pact that permits inflicting intentional harm to certain animals in a laboratory setting, but would prohibit the same treatment in a lay one. Take the treatment of lab rats. We understand that there is a trade-off worth making between the pain and suffering inflicted on the rodents and the potential gains in mitigating future pain and suffering among humans (and perhaps other animals as well). But the context matters because animal cruelty charges could surely be laid against a lay individual injecting various substances into a collection of pet rats.

    The line where such an acceptable trade-off lies is murky and has changed rapidly over the past century. As we learn more about the cognitive abilities of nonhuman animals, I suspect the line will continue to move. We’ve already seen this in the US with the NIH phasing out all lab chimp research. And there continues to be massive pushback against captive cetacean research (well justified, in my opinion).

    There are fascinating and thorny issues here. As for the treatment of the ants, it’s worth thinking about, especially if the research could not plausibly be construed to aid in the operation of mitigating future potential pain and suffering (human or otherwise).

  52. eric
    Posted February 16, 2018 at 6:32 pm | Permalink

    I can see the evolutionary advantage to this overall process, but what could be the evolutionary advantage of the ‘soccer fall’ malingering behavior? I would think that in a colony organism like ants, the most adaptive behavior would be to give accurate information to the colony about your condition. The ant’s genes lose if the colony spends resources “saving” an ant that can walk on it’s own, or saving an ant that can’t be saved, and the worker itself has no genetic incentive to saving themselves over a sister or the queen.

  53. Posted February 16, 2018 at 6:50 pm | Permalink

    When National Lampoon ran a cover threatened to ‘shoot the dog’ it was not funny. The one will the kitten is even less funny now. Especially after a mass shooting. You are better than this.

  54. Frank
    Posted February 16, 2018 at 8:09 pm | Permalink

    Great article and very cool vids. I have to admit I’m also a little uncomfortable with the notion of deliberately injuring the ants whereas when mice are “injured” for medical research there is at least the notion that it will lead to alleviating human suffering. Agree with Ed Kroc that it’s a sticky issue.

  55. eliz20108
    Posted February 16, 2018 at 9:12 pm | Permalink

    I am a woman who is commenting. I enjoyed reading this article. I cannot comment on it bc I do not have the knowledge. I want to continue to read scientific emails.

    Please continue writing articles like this on the ants.

    • ThyroidPlanet
      Posted February 17, 2018 at 9:35 am | Permalink

      PCC(E) says (paraphrased)

      It isn’t a dumb question if you’re interested in the answer

      … (it’s me again) : just try!

  56. ploubere
    Posted February 16, 2018 at 11:10 pm | Permalink

    I read it, and was educated. Thank you.

  57. Posted February 17, 2018 at 1:29 am | Permalink

    Fascinating as this is, someone call PETA.

  58. Dale Franzwa
    Posted February 17, 2018 at 1:36 am | Permalink

    Oh, Jerry, please don’t shoot that cute innocent kitty. I read the article. It was fascinating. But those terrible researchers! Crushing, mutilating those poor little ants. Go ahead and shoot them instead. Sorry, the devil made me say this.

  59. Posted February 17, 2018 at 6:11 am | Permalink

    So, does the meiosis math mean that every worker has 3 chromosomes per set, 2 from the father and one from the queen? Please explain to us non-biology majors who barely remember how human genetics is supposed to work.

  60. Bob
    Posted February 17, 2018 at 7:29 am | Permalink

    I noted that several ants inspected the wounded ant. It was, if I followed the milling correctly, an ant who came along third or fourth that carried the wounded ant away. Could it be that some ants are designated as CERT trained and not others?

  61. ThyroidPlanet
    Posted February 17, 2018 at 9:33 am | Permalink

    In haste :

    Do ants with five-leg injuries produce the same quantities of the dimehtl disulfide or … the other one?

    ^^^^ not proof read b/c I’m in a jam.

  62. Posted February 17, 2018 at 10:19 am | Permalink

    Intriguing

  63. Mark R.
    Posted February 17, 2018 at 2:29 pm | Permalink

    I wanted to be #124 to comment on a science post! It seems the peeps like ants! I know I do.

  64. Posted February 17, 2018 at 5:11 pm | Permalink

    No need to threaten kittens, as I like the science posts anyway. I also love ants – my lecturer on my ecology course was Dr Cherrett, who published many papers on ants.

  65. Carly
    Posted February 17, 2018 at 9:31 pm | Permalink

    Wow! That’s pretty cool. I don’t even like ants, really, but this is still really interesting.

  66. Ullrich Fischer
    Posted February 18, 2018 at 10:14 pm | Permalink

    Ok. I read this fascinating article despite your hollow threat to murder that kitty! I know from past posts that you would never do such a thing. 🙂


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