New Research Documents Selective Tool Use in Ants

In an exciting new study recently available online in the journal Animal Behaviour, researchers found that two species of ants are selective in their use of tools for liquid food transport. Although tool use in ants has already established in previous studies, the mechanisms involved in tool use selection have rarely been investigated. Dr. István Maák and colleagues found that ants exhibit selective behavior in tool use, preferring materials that exhibit optimal handling and/or soaking properties. Perhaps most intriguing, the ants learned to preferentially use artificial tools that have superior properties for liquid food transport when compared to tools in their natural environment.

aphaenogasterants
Aphaenogaster ants feed on a seed food body. Photo credit: Alex Wild

The ants in question are two species in the widespread genus AphaenogasterA.subterranean and A. senilis. These species, along with other Aphaenogaster species, lack a distensible crop, limiting the amount of food that workers are able to carry internally. This limitation may have promoted the evolution of tool use, which allows workers to more efficiently transport food. In particular, these ants place debris into liquid food sources, and then carry the soaked debris back to their nest.

To test for tool selectivity, Dr. Maák and colleagues designed a clever experiment where they offered a liquid food source and several different types of tools for use by the ants. Then, they documented the number and type of tools transported to and from the nest over a period of 3 hours. Using statistical analyses, the researchers then compared the number of tools used in order to determine any preferences in tool use.

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Testing tool selectivity in Aphaenogaster ants. Figure from Maák et al. 2016.

In the end, the study authors found that despite having a variety of tools from which to choose, the ants preferentially used certain tools, including artificial ones that they could not have previously experienced in nature. This demonstrates that the ants are flexible in their tools use and will adjust their behavior in response to new materials that they discover. Such behavioral flexibility, if widespread across different species, may contribute to the ecological success of ants seen in many terrestrial ecosystems around the world.

10 thoughts on “New Research Documents Selective Tool Use in Ants

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  1. I like your blog! Good work.

    I had a discussion with a friend of mine who studies bio-mechanics. About this paper, while i think their ability to use different materials selectively is remarkable, the word tool-use (like they also mention in a line somewhere at the end) is not correct for this. So if i use a water bottle to drink, is that my tool or i am just using an object? If I climb stairs, are they my tools or I am just using something that is in the environment?
    As opposed to, if a raven uses a stick to get the reward out of a glass tube (which is called tool use because it involves a ‘mechanical movement’ of something using a tool), or if I use a screwdriver to help me move something that I cannot do otherwise?
    They even mention the apes using sticks to scoop something as tool use, is spoon a tool or just an object that helps me scoop? The point is, one uses a tool to move something mechanically, here the ants use the objects to move water around.
    So perhaps object-use is more suitable

    Ravi
    https://antists.wordpress.com

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    1. Hi Ravi, thanks for stopping by!

      I admit that at first blush, I was (and still am, a little) skeptical about calling this “tool” use. However, I think in the end it makes sense to call this tool use. This is because there is mechanical movement – the ants not only break the material into small fragments for use, but they also pick up the pieces and place it into a food source, pick it up again, and then use it to carry the food back to the nest. Very different from just walking up steps that are already a feature of the environment – there is a manipulation of materials for use in order to acquire a food resource. I really don’t see how this is substantively different from humans using a shovel. In fact, I think it’s actually in some ways more complex than a raven using a stick to get a reward, because of the place-wait-pick up series of actions. Would you call a sponge a tool? I would!

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      1. <"because of the place-wait-pick up series of actions"
        Consider the series of actions you mention.

        In the case of using a shovel, we use that as a tool which we move mechanically using our motor control to achieve the job of moving dirt. In the ants case, the ants just place their tool in water (or sugar water) and wait for it to soak up and then carry it home. There is no similar mechanical movement involved like using shovel where the user (human) gets mechanical feedback while using the tool and he/she uses that mechanical movement to achieve the outcome.

        Similar argument with the sponge.

        I do consider this behaviour remarkable though, but just that it is a good problem-solving or object-use rather than tool use

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      2. Hm, I guess I just disagree haha. I think narrowly defining “tool use” to require that fairly specific type of mechanical action is a little unusual.

        Take the Merriam-Webster 1a definition: “a handheld device that aids in accomplishing a task”. Ants don’t have hands, but to the extent that their mandibles serve as hand-equivalents, this would classify as handheld. The fact that they alter and manipulate an object in their environment and use the object to carry other objects (liquid food) elevates this behavior to the simplest form of tool use.

        As another example, what about a bucket? If I take a bucket, place the bucket under a faucet, and then transport the bucket to another location, that doesn’t count as tool use? I would call that tool use!

        Liked by 2 people

  2. That is the major problem with many studies right; different people define stuff differently! And recently, people like such newsworthy words so one tends to use them more (often without any hidden intentions)

    It is not about having hands or hand-equivalent. And the definition I was going by does not define any such ‘specific’ action. It is just using an object to mechanically (involving general motor actions and feedback) achieve something. So using shovel, screwdriver etc are tool use. Chimps using stones to break something is a tool. Raven using a stick to take out rewards out of a tube is tool use.
    Ravens do not have to have hands to use tools. Similarly, say if an ant uses a stick to ‘move’ something, then it would be a tool. But here the ants use the object to transport water just like a bucket which according to the definition is not called tool use.

    I feel like the arguments are similar with the problem of consciousness. ‘What is consciousness?’ is the main debate because there is no single definition that every one agrees on.

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    1. Well I suppose that when it really comes down to it, explicitly defining (in the paper/study) what is meant by potentially controversial terms would help to prevent these sort of disagreements. In any case, thanks for the discussion!

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  3. I forgot to mention, I had observed this behaviour during the Antcourse this year. I was super excited about this and had even showed to everyone. I only had sand/mud granules in my case. Your labmate Supriya was also there.
    I was excited to read this paper. Anyway, I should really get to back to my lab work now!

    Liked by 1 person

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