The Daily Ant hosts a weekly series, Philosophy Phridays, in which real philosophers share their thoughts at the intersection of ants and philosophy. This is the twelfth contribution in the series, submitted by Kevin Lande.


O Ant, Where Art Thou?

Do ants have any idea where they are and where home is at? When they go out into the world, do they grasp how far they have gone or what turns their path has taken? Desert ants (Cataglyphis) are able reliably to return to their homes, having left them in search of food. But the ability to reliably get back home does not imply that one has an idea, a mental representation or map, that specifies where in space home is located. Reflecting on why not helps us to get some purchase on a broader question: What sorts of abilities, or behaviors, indicate the presence of such mental representations? What abilities or behaviors indicate the presence of mind?

Huertas abandonadas VIII

Cataglyphis ant in search of home, maybe. Photo: José María Escolano

Take an example from my childhood. It once happened that I was lost in a large outlet store. I had no idea where the entrance was. So I devised a strategy: I would walk in a straight line until I arrived at a wall. I would then follow the wall around until either I reached the entrance or I returned back to the starting point, which I would recognize by the toddler-sized tub of nerf balls. Were the latter thing to happen, I would begin to circle in on the center of the store. I did, eventually, find my way out of that outlet store. But at no point in my meandering through the aisles did I have an idea of where the entrance was. Perhaps I had an idea of what the entrance looks like (and likewise for the barrel of nerf balls). But our question is whether I had any idea of where the entrance was located. Intuitively, my ability to find the entrance did not rely on my having an idea or mental map of the entrance’s location in the outlet store. (Some of you, waxing all metaphysical-like, will say that my strategy demonstrated that I at least knew that the entrance was somewhere in the store. But I swear my strategy would have worked even if I hadn’t known that. The success of the strategy doesn’t require, and hence does not imply, that I have an idea of the entrance’s being located in the store.)

Of course, there are more directed strategies for finding one’s way. Take another memory from my childhood. My parents brought my siblings and me to celebrate Passover with another family. The father of this other family told us that he had hidden a piece of matzo somewhere on the first floor of the house. Whoever found the matzo would receive a prize—one of even greater value than the matzos itself. (Vast quantities of geld, as it turned out.) As the evening matured and the adults grew tired and, still, the matzo was not found, the adults resorted to giving us clues. If we were looking in the right area, they would shout “Warm!” In the wrong areas they would shout “Cold!” If we were really on the money, we might hear them collapse into paroxysms of “HOT! HOT! HOT!” Eventually, utilizing this system of temperature-based guidance, one of us did find the matzo. (It was behind the sofa. As it was every year.) But I propose that in the course of this game, and even with our system of clues, none of us children had any idea where the matzo was.

That system of temperature-based guidance is an instance of what comparative psychologists called “homing” or “beaconing.” It is a central strategy by which salmon find their mating grounds—except that salmon go by olfaction, following the power of a scent rather than the impatient hints of a tired Jewish parent. To paraphrase the philosopher Tyler Burge, you can make this system as reliable and precise as you like, but the salmon have as little or less of an idea where in the world their mating grounds are than we children had of where in the house the matzo was hidden. Once again, the ability to get somewhere does not imply that one has an idea of the location of one’s destination.

Desert ants are more sophisticated than those salmon beaconing their way home or us children trying to find the matzo on the basis of our parents’ clues. (I mean—of course us children were more sophisticated in many respects. There are limits to this analogy.) When the ant has found what it wants, it reorients its body and heads straight in the direction of home (see Figure 1). Once it is near home, it begins walking around in concentric circles—like sailing on the open sea, dead reckoning is a noisy process and the circling strategy allows the ant to overcome the error. These ants appear to use something like the same strategy that sailors have used for a very long time to plan their movements: they keep track of information that corresponds with how far they have gone and in what direction. On the basis of this information, the ants compute an estimate of how they should orient themselves on their homeward journey and when they should begin to feel their journey is nearing completion. This strategy requires that the ant’s navigational system perform some calculus or some simpler approximation of calculus. These calculations probably are automatic and follow “hard-wired” rules.

Those who like calculus call this sort of strategy or computation path integration; sailors who like logic call it deductive reckoning; the saltier sailors call it dead reckoning.

 

FoodToNest

Figure 1. Taken from here.

 

So, is dead reckoning a sign of a mental life that contains representations of where in space home is located? While many have thought so (cf. Randy Gallistel), others are a bit skeptical. Allow me to paraphrase, again, Tyler Burge. What is the ant really doing? Similar to my mother on a hike, the ant is keeping track of its distance by tracking things like the total amount of stress on its joints since it left home. To keep track of its direction, the ant keeps track of the orientation of the polarized patterns of light that land on its eyes. (The ant also tracks the direction of the light, which corresponds to the position of the sun in the sky.) When the ant has found its food, it reorients its body relative to those patterns of light on the eye and begins walking until it senses its joints have been stressed enough, and then it begins to circle in on home. Does being able to face the right direction and walk the right number of steps on the basis of how stressed your joints are and the polarized patterns of light that land on your eyes imply that you have an idea of where home is located? The ant has a reliable strategy, to be sure. But the whole lesson so far has been that having a reliable ability to get back home does not mean one has an idea of where home is located.

So what would show that the ants have an idea of where home is? I’ll set this question aside for another Phriday.

Recommended readings

(or: The foregoing was pieced together from scraps of the following texts)

Burge, Tyler. (2010). Origins of Objectivity. New York: Oxford University Press. Pp. 492–518.

Gallistel, C.R. (1990). “Representations in animal cognition: An introduction.” Cognition, vol. 37: pp. 1–22.

Müller, Martin and Wehner, Rüdiger. (1988). “Path integration in desert ants, Cataglyphyis fortis.” Proceedings of the National Academy of Science of the United States of America, vol. 85: pp. 5287–5290

Shettleworth, Sara J. (2010). Cognition, Evolution, and Behavior (2nd ed.). New York: Oxford Unviversity Press. Ch. 8.

Wehner, Rüdiger and Müller, Martin. (2006). “The significance of direct sunlight and polarized skylight in the ant’s celestial system of navigation.” Proceedings of the National Academy of Sciences of the United States of America, vol. 103, no. 33: pp. 12575–12579.

 


KevinLandeKevin Lande is a PhD candidate in philosophy at UCLA. His interests lie in philosophy of mind and philosophy of psychology. Lande will soon be on the market, where he is expected to be a hot commodity as not reported in The New York Times and The Washington Post.