Ants use tools

What does that mean in the evaluation of intelligence?

They’re tiny, colonial and each of them has a specific role in their colony. If something that small with such a regimented life has figured out how to use tools, how much of an indicator of intelligence is tool use?

What tools do ants use and how do they use them?

Some ants of the genus Aphaenogaster have been proven to use tools. One definition of tool use, as I noted in my article about Veronika, the tool using cow, is: the manipulation of an external object to achieve a goal via a mechanical interface, ‘tooling’ ranges from species-typical routines to innovative, problem-specific acts. What if tool use is only used for species-typical routines? Is that an indicator of intelligence, genetics or a specific type of intelligence?

Some ants use leaves to transport food Photo by Christian Holzinger on Unsplash

Ants only use tools found in their environment: twigs, pieces of leaf and soil. They drop these tools into liquid or semi-solid food sources, let them soak up the food, then carry the food-soaked tools back to their nests for their nestmates. Ants have crops, expandable muscular pouches near the throat, but unlike birds, ants can’s stretch their crops to hold more food. Thus, by soaking the food into items they can carry, they increase the amount of food they can bring to the nest. And so far, it seems that only one type of ant performs this task. You guessed it, the workers.

Tool use: not a defense against drowning?

The parsimonious (simplest) interpretation of why ants drop sticks, etc. into fluids was to prevent themselves from drowning, which might alone be considered tool use and, therefore, potential intelligence. This thesis was disproved during controlled tests where ants were exposed to plain water and honey water. No ants dropped sticks into the plain water, something it would be logical to do if they were trying to avoid drowning. Instead, they selectively used their tools to absorb nutrients, the honey in the water.

Also, the worker ants dropped more ‘tools’ into nutrient rich water when they were farther from their nest, indicating they were aware of the distance from the food source and the nest, optimizing their travel to collect as much food as possible. And they continued dropping tools into ever-diminishing sources, seeming to make the effort to get as much value as possible from each site.

And they do show some flexibility. The ants in the study chose different tools and sizes of tools based on the type of liquid they collected, the distance it needed to be transported, and the types of tools available. They also modified some tools provided in a study, sponges for example, to make them easier to handle during foraging and transport.

But there are still areas of grey in this work. Ants often drop tools or cover liquids using larger tools than those used in transporting food. Does this constitute protection from drowning or are there food sources under the liquid the ants are hiding from competitors? The authors suggest that debris dropping could have more than one function depending on the situation. Workers might be burying food to save for later or possibly be hiding it from competitors. Or both. All very interesting findings.

Does tool use = intelligence or not?

I seem to be on a tool use track these days. But the exploration of ant tool use has raised new questions in my mind about the relationship between tool use and animal intelligence. Let’s back to Veronika the cow, and the definition used in that article which gives a range of tool use from species typical routines to innovative, problem-specific acts.

I think ant tool use falls into the species typical routines mode, which, to my mind is less indicative of a high level of intelligence than the actions of Veronika. Unless of course, Veronika had already had her back scratched with a brush by her person.

If that was the case, then Veronika learned from her person that she could use a brush to scratch an itch (as it were) rather than innovating completely on her own. That’s much more like what the ants do.

The troop of worker ants goes out and they all do the same thing, probably learning at least some aspects from each other. Granted there is variation in the selection of tools and the way they are used. And some intelligence is needed to select the correct tools, use them appropriately and transport them back to the nest. But I tend to think ants remain in the species typical routine class. As for cows, I’ll need more information.