Two obvious abilities that separate people from the rest of the animals are language and tool use. Of course even very primitive animals use objects in their environments, birds, for example, use nests. But humans display the ability to learn to use tools, while the simpler animals only can use those objects that they have been evolved to. The bird’s genes allow it to build a nest, but it is our minds that let us use a hammer. Both abilities are a bit of a mystery; we haven’t successfully developed software that can use language or which can learn to use tools. Since language usually gets all of the attention today I am going to focus primarily on tool use, and investigate what makes us able to use tools when other animals can’t.
Perhaps saying that those two abilities distinguish humans from the rest of the animals is a bit misleading though. Obviously no other animals can use tools or language in the same way we can. However, certain other primates seem to display primitive forms of language, and can even be taught simple languages understandable by us, which they can go on to teach each other. And these same primates seem to be able to master some simple tools as well. This raises the interesting possibility that somehow language and tool use are connected, that their appearance in the same species is more than a coincidence. Perhaps being able to use language is a prerequisite for being able to use tools, or vice versa, or possibly there is some common cognitive capability that is responsible for both of them. But, then again, given that we have so few samples to draw on it could very well be that it is coincidence that the species we know of display both language and tool use.
It’s hard to believe that language is somehow responsible for our ability to use tools, simply because tool use doesn’t seem much like a linguistic act; using a tool doesn’t serve to express a thought. Of course language could be construed as a kind of tool for manipulating people, in a very broad understanding of what a tool is, and from that angle it might seem plausible to claim that the ability to use tools underlies language. But I doubt this is a reasonable connection to make, simply because the way in which language is a tool would make any ability a tool. The ability to use tools seems to necessarily involve a capacity to pick up, and possibly shape objects, and then use them purposefully to accomplish something that couldn’t be don’t without them. And, although we can do things with language that would be impossible without it, language is certainly not a case where we must use objects to do what we wish. Language thus seems as much as an example of tool use as running is, given that we can accomplish things by running that we couldn’t do by walking. Thus if there is a connection between the two what we must be looking for is some common ability that underlies the both of them, that once it exists can manifest itself both as the ability to use tools and language.
Towards that end we might look for what capabilities allow us to use language and which allow us to use tools and see whether there is some overlap. Language is certainly the simpler case so we can take a brief look at it to begin. The primary cognitive capability behind language is the ability to allow one thing to stand for another, specifically that allows us to take certain symbols as standing for other things or ideas. And of course the capability to learn makes language practically possible, because it allows us to develop such representative connections without being born knowing them. But, when it comes to what allows us to use tools, the answer isn’t so obvious, probably because we have spent much less time thinking about the matter. Making machines that can learn and communicate has always seemed the higher priority, tool use is often something that is thought to be a problem that will be simple to solve once we have the first two mastered. And maybe it will be, but that those priorities haven’t left us with an easy way to think about what goes into it.
We might suppose that tool use is simply the product of being able to learn from experience. We could even tell a story about how tools begin to be used invoking only that capability in an explanatory role. Suppose, we say, that an individual is simply toying with some object in their environment, an accidental behavior that serves no purpose. And sometimes they won’t put these objects down when they go about some important task. This opens up the possibility that the object already in hand will simply happen to be useful for that task. Success with that object reinforces that behavior, and thus tool use is born, as the individual will develop a tendency to pick up the same object again when they go about that task in the future. But many animals have the capability to learn from experience, although some better than others. And yet it is only a few species that do display tool using behavior. Again, this may be because of an accident of nature, it may be that the primates are simply the only species with the right biological equipment (thumbs) to use tools. But, on the other hand, if tool use really was that easy then we would expect many animals to be able to use very simple tools with just their mouths. And since tool use is advantageous evolution would select for those individuals that are better able to use tools, which would eventually result in animals with the right equipment. So I suspect that in this simple story there is something missing, something that prevents most animals from using tools in the way described.
It is possible that what the rest of the animals are missing is some form of curiosity or willingness to experiment that drove our ancestors to fiddle with sticks and try poking things with them later. While that does explain why we are different than the rest of the animals it leaves a number of questions unanswered. First of all curiosity doesn’t seem like something that would be that hard to evolve, and so if curiosity was really the key to tool use then we would expect more species to exhibit it. Secondly, it doesn’t explain why the primates that are able to use simple tools are unable to develop more complex ones. If the barrier is really just the unwillingness of most animals to try new things the primates, who do try new things, should display essentially the same capacity for tool use as we do. So if curiosity isn’t the culprit we might instead finger our more developed ability to model the world in our mind and to plan out complex actions. Instead of supposing that tool use is developed by random experimentation we might instead attribute it to moments of discovery, when an individual realizes that an object used in a certain way might work better than their natural equipment. And such moments are only possible if we can envision the outcome of events at a sufficient level of detail to both predict outcomes where nothing similar has happened before and to build up those predictions from general rules rather than a collection of observations about specific objects and their interactions (because that would prevent us from being able to mentally add a new object into the mix). This explanation is better than the previous one, because it explains how tool use can come in degrees, based on how well the tool users are able to mentally model the world. However, now our explanation seems to be working against us; the ability to model the world seems more complicated than the ability to use tools and thus in need of an explanation itself. To satisfy our curiosity about the connection between tool use and language we need either something simpler or to break down that capacity into its own components.
Rather than following this road any farther let’s start over, and this time attack the problem from the opposite direction; instead of trying to find the explanation for why we can use tools by itself and then seeing whether it overlaps with our ability to use language, let us proceed on the assumption it does, and see if we can explain our ability to use tools on the basis of any capabilities behind our ability to use language. If they are to have something in common then it must be the ability to allow one thing to stand for another, since the capacity to learn has been rejected earlier as a sole explanation. This suggests that we might attribute our ability to use tools to our ability to associate certain actions or goals with the objects that are the tools themselves. Conceptually this would be the transition from seeing a stick as a stick to seeing a stick as both a stick and a pointy thing to get food with. Without this capacity we might suppose that systematic tool use would be impossible. At best the animal could learn behaviors, and maybe if the tools were always in a fixed spot a very complicated behavior could be developed involving fetching a tool and then doing something with it. But this doesn’t allow the kind of developments that real tool use comes with, for example the ability to substitute similar objects for each other; although a hammer is a hammer anything heavy and hard can be a hammer too in a pinch. Obviously this is, as described here, at best an incomplete proposal. How exactly do associations work? What gets associated with what? And how exactly do they lead to complicated tool use? I’ll set aside such questions for the moment and simply say that it has the ring of truth about it, and explains nicely why language and tool use seem to come hand in hand without appeal to some ill conceived idea of a linear range of intelligence where they both fall near the top.